Adding upstream version 115.7.0esr.upstream/115.7.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

620 files changed, 17574 insertions, 0 deletions

diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/basic.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/basic.js
new file mode 100644
index 0000000000..60f29323c6
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/basic.js
@@ -0,0 +1,17 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime
+description: Basic tests for the PlainTime constructor.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const args = [15, 23, 30, 123, 456, 789];
+const plainTime = new Temporal.PlainTime(...args);
+TemporalHelpers.assertPlainTime(plainTime, ...args);
+assert.sameValue(plainTime.calendar.id, "iso8601", "calendar");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/builtin.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/builtin.js
new file mode 100644
index 0000000000..067ea7ae43
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/builtin.js
@@ -0,0 +1,30 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime
+description: Tests that Temporal.PlainTime meets the requirements for built-in objects
+info: |
+    Unless specified otherwise, a built-in object that is callable as a function is a built-in
+    function object with the characteristics described in 10.3. Unless specified otherwise, the
+    [[Extensible]] internal slot of a built-in object initially has the value true.
+
+    Unless otherwise specified every built-in function and every built-in constructor has the
+    Function prototype object [...] as the value of its [[Prototype]] internal slot.
+features: [Temporal]
+---*/
+
+assert.sameValue(Object.isExtensible(Temporal.PlainTime),
+  true, "Built-in objects must be extensible.");
+
+assert.sameValue(Object.prototype.toString.call(Temporal.PlainTime),
+  "[object Function]", "Object.prototype.toString");
+
+assert.sameValue(Object.getPrototypeOf(Temporal.PlainTime),
+  Function.prototype, "prototype");
+
+assert.sameValue(typeof Temporal.PlainTime.prototype,
+  "object", "prototype property");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-cast.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-cast.js
new file mode 100644
index 0000000000..afc4472701
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-cast.js
@@ -0,0 +1,22 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: compare() casts its arguments
+features: [Temporal]
+---*/
+
+const t1 = Temporal.PlainTime.from("08:44:15.321");
+const t2 = Temporal.PlainTime.from("14:23:30.123");
+
+assert.sameValue(Temporal.PlainTime.compare({ hour: 16, minute: 34 }, t2), 1, "one object");
+assert.sameValue(Temporal.PlainTime.compare("16:34", t2), 1, "one string");
+assert.throws(TypeError, () => Temporal.PlainTime.compare({ hours: 16 }, t2), "one missing property");
+
+assert.sameValue(Temporal.PlainTime.compare(t1, { hour: 16, minute: 34 }), -1, "two object");
+assert.sameValue(Temporal.PlainTime.compare(t1, "16:34"), -1, "two string");
+assert.throws(TypeError, () => Temporal.PlainTime.compare(t1, { hours: 16 }), "two missing property");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-number.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-number.js
new file mode 100644
index 0000000000..0cf5db1ea0
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-number.js
@@ -0,0 +1,38 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: A number is converted to a string, then to Temporal.PlainTime
+features: [Temporal]
+---*/
+
+const arg = 123456.987654321;
+
+const result1 = Temporal.PlainTime.compare(arg, new Temporal.PlainTime(12, 34, 56, 987, 654, 321));
+assert.sameValue(result1, 0, "123456.987654321 is a valid ISO string for PlainTime (first argument)");
+const result2 = Temporal.PlainTime.compare(new Temporal.PlainTime(12, 34, 56, 987, 654, 321), arg);
+assert.sameValue(result2, 0, "123456.987654321 is a valid ISO string for PlainTime (second argument)");
+
+const numbers = [
+  1,
+  -123456.987654321,
+  1234567,
+  123456.9876543219,
+];
+
+for (const arg of numbers) {
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.compare(arg, new Temporal.PlainTime(12, 34, 56, 987, 654, 321)),
+    `Number ${arg} does not convert to a valid ISO string for PlainTime (first argument)`
+  );
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.compare(new Temporal.PlainTime(12, 34, 56, 987, 654, 321), arg),
+    `Number ${arg} does not convert to a valid ISO string for PlainTime (second argument)`
+  );
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-calendar-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-calendar-annotation.js
new file mode 100644
index 0000000000..89ca951175
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-calendar-annotation.js
@@ -0,0 +1,38 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: Various forms of calendar annotation; critical flag has no effect
+features: [Temporal]
+---*/
+
+const tests = [
+  ["12:34:56.987654321[u-ca=iso8601]", "without time zone"],
+  ["12:34:56.987654321[UTC][u-ca=iso8601]", "with time zone"],
+  ["12:34:56.987654321[!u-ca=iso8601]", "with ! and no time zone"],
+  ["12:34:56.987654321[UTC][!u-ca=iso8601]", "with ! and time zone"],
+  ["T12:34:56.987654321[u-ca=iso8601]", "with T and no time zone"],
+  ["T12:34:56.987654321[UTC][u-ca=iso8601]", "with T and time zone"],
+  ["T12:34:56.987654321[!u-ca=iso8601]", "with T, !, and no time zone"],
+  ["T12:34:56.987654321[UTC][!u-ca=iso8601]", "with T, !, and time zone"],
+  ["1970-01-01T12:34:56.987654321[u-ca=iso8601]", "with date and no time zone"],
+  ["1970-01-01T12:34:56.987654321[UTC][u-ca=iso8601]", "with date and time zone"],
+  ["1970-01-01T12:34:56.987654321[!u-ca=iso8601]", "with !, date, and no time zone"],
+  ["1970-01-01T12:34:56.987654321[UTC][!u-ca=iso8601]", "with !, date, and time zone"],
+  ["1970-01-01T12:34:56.987654321[u-ca=iso8601][u-ca=discord]", "second annotation ignored"],
+  ["1970-01-01T12:34:56.987654321[u-ca=iso8601][!u-ca=discord]", "second annotation ignored even with !"],
+];
+
+tests.forEach(([arg, description]) => {
+  const result = Temporal.PlainTime.compare(arg, arg);
+
+  assert.sameValue(
+    result,
+    0,
+    `calendar annotation (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-critical-unknown-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-critical-unknown-annotation.js
new file mode 100644
index 0000000000..80d9ad6353
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-critical-unknown-annotation.js
@@ -0,0 +1,34 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: Unknown annotations with critical flag are rejected
+features: [Temporal]
+---*/
+
+const invalidStrings = [
+  "00:00[!foo=bar]",
+  "T00:00[!foo=bar]",
+  "1970-01-01T00:00[!foo=bar]",
+  "1970-01-01T00:00[UTC][!foo=bar]",
+  "1970-01-01T00:00[u-ca=iso8601][!foo=bar]",
+  "1970-01-01T00:00[UTC][!foo=bar][u-ca=iso8601]",
+  "1970-01-01T00:00[foo=bar][!_foo-bar0=Dont-Ignore-This-99999999999]",
+];
+
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.compare(arg, new Temporal.PlainTime(12, 34, 56, 987, 654, 321)),
+    `reject unknown annotation with critical flag: ${arg} (first argument)`
+  );
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.compare(new Temporal.PlainTime(12, 34, 56, 987, 654, 321), arg),
+    `reject unknown annotation with critical flag: ${arg} (second argument)`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-date-with-utc-offset.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-date-with-utc-offset.js
new file mode 100644
index 0000000000..872946545a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-date-with-utc-offset.js
@@ -0,0 +1,55 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: UTC offset not valid with format that does not include a time
+features: [Temporal]
+---*/
+
+const validStrings = [
+  "12:34:56.987654321+00:00",
+  "12:34:56.987654321+00:00[UTC]",
+  "12:34:56.987654321+00:00[!UTC]",
+  "12:34:56.987654321-02:30[America/St_Johns]",
+  "1976-11-18T12:34:56.987654321+00:00",
+  "1976-11-18T12:34:56.987654321+00:00[UTC]",
+  "1976-11-18T12:34:56.987654321+00:00[!UTC]",
+  "1976-11-18T12:34:56.987654321-02:30[America/St_Johns]",
+];
+
+for (const arg of validStrings) {
+  const result = Temporal.PlainTime.compare(arg, arg);
+
+  assert.sameValue(
+    result,
+    0,
+    `"${arg}" is a valid UTC offset with time for PlainTime`
+  );
+}
+
+const invalidStrings = [
+  "2022-09-15Z",
+  "2022-09-15Z[UTC]",
+  "2022-09-15Z[Europe/Vienna]",
+  "2022-09-15+00:00",
+  "2022-09-15+00:00[UTC]",
+  "2022-09-15-02:30",
+  "2022-09-15-02:30[America/St_Johns]",
+];
+
+for (const arg of invalidStrings) {
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.compare(arg, new Temporal.PlainTime(12, 34, 56, 987, 654, 321)),
+    `"${arg}" UTC offset without time is not valid for PlainTime (first argument)`
+  );
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.compare(new Temporal.PlainTime(12, 34, 56, 987, 654, 321), arg),
+    `"${arg}" UTC offset without time is not valid for PlainTime (second argument)`
+  );
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-multiple-time-zone.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-multiple-time-zone.js
new file mode 100644
index 0000000000..48df14dc1a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-multiple-time-zone.js
@@ -0,0 +1,34 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: More than one time zone annotation is not syntactical
+features: [Temporal]
+---*/
+
+const invalidStrings = [
+  "00:00[UTC][UTC]",
+  "T00:00[UTC][UTC]",
+  "1970-01-01T00:00[UTC][UTC]",
+  "1970-01-01T00:00[!UTC][UTC]",
+  "1970-01-01T00:00[UTC][!UTC]",
+  "1970-01-01T00:00[UTC][u-ca=iso8601][UTC]",
+  "1970-01-01T00:00[UTC][foo=bar][UTC]",
+];
+
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.compare(arg, new Temporal.PlainTime(12, 34, 56, 987, 654, 321)),
+    `reject more than one time zone annotation: ${arg} (first argument)`
+  );
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.compare(new Temporal.PlainTime(12, 34, 56, 987, 654, 321), arg),
+    `reject more than one time zone annotation: ${arg} (second argument)`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-no-implicit-midnight.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-no-implicit-midnight.js
new file mode 100644
index 0000000000..a84fabc012
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-no-implicit-midnight.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: RangeError thrown if a date-only string is passed in a PlainTime context
+features: [Temporal, arrow-function]
+---*/
+
+const arg = "2019-10-01";
+const midnight = new Temporal.PlainTime();
+assert.throws(
+  RangeError,
+  () => Temporal.PlainTime.compare(arg, midnight),
+  "Date-only string throws, does not implicitly convert to midnight (first argument)"
+);
+assert.throws(
+  RangeError,
+  () => Temporal.PlainTime.compare(midnight, arg),
+  "Date-only string throws, does not implicitly convert to midnight (second argument)"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-time-designator-required-for-disambiguation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-time-designator-required-for-disambiguation.js
new file mode 100644
index 0000000000..62605b475b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-time-designator-required-for-disambiguation.js
@@ -0,0 +1,50 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: ISO 8601 time designator "T" required in cases of ambiguity
+includes: [temporalHelpers.js]
+features: [Temporal, arrow-function]
+---*/
+
+const midnight = new Temporal.PlainTime();
+
+TemporalHelpers.ISO.plainTimeStringsAmbiguous().forEach((string) => {
+  let arg = string;
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.compare(arg, midnight),
+    `'${arg}' is ambiguous and requires T prefix (first argument)`
+  );
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.compare(midnight, arg),
+    `'${arg}' is ambiguous and requires T prefix (second argument)`
+  );
+  // The same string with a T prefix should not throw:
+  arg = `T${string}`;
+  Temporal.PlainTime.compare(arg, midnight);
+  Temporal.PlainTime.compare(midnight, arg);
+
+  arg = ` ${string}`;
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.compare(arg, midnight),
+    `space is not accepted as a substitute for T prefix (first argument): '${arg}'`
+  );
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.compare(midnight, arg),
+    `space is not accepted as a substitute for T prefix (second argument): '${arg}'`
+  );
+});
+
+// None of these should throw without a T prefix, because they are unambiguously time strings:
+TemporalHelpers.ISO.plainTimeStringsUnambiguous().forEach((arg) => {
+  Temporal.PlainTime.compare(arg, midnight);
+  Temporal.PlainTime.compare(midnight, arg);
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-time-separators.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-time-separators.js
new file mode 100644
index 0000000000..2d2f5ecef9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-time-separators.js
@@ -0,0 +1,34 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: Time separator in string argument can vary
+features: [Temporal]
+---*/
+
+const plainTime = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+const tests = [
+  ["1976-11-18T12:34:56.987654321", "uppercase T"],
+  ["1976-11-18t12:34:56.987654321", "lowercase T"],
+  ["1976-11-18 12:34:56.987654321", "space between date and time"],
+  ["T12:34:56.987654321", "time-only uppercase T"],
+  ["t12:34:56.987654321", "time-only lowercase T"],
+];
+
+tests.forEach(([arg, description]) => {
+  assert.sameValue(
+    Temporal.PlainTime.compare(arg, plainTime),
+    0,
+    `variant time separators (${description}), first argument`
+  );
+
+  assert.sameValue(
+    Temporal.PlainTime.compare(plainTime, arg),
+    0,
+    `variant time separators (${description}), second argument`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-time-zone-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-time-zone-annotation.js
new file mode 100644
index 0000000000..ef127bdfac
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-time-zone-annotation.js
@@ -0,0 +1,48 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: Various forms of time zone annotation; critical flag has no effect
+features: [Temporal]
+---*/
+
+const tests = [
+  ["12:34:56.987654321[Asia/Kolkata]", "named, with no offset"],
+  ["12:34:56.987654321[!Europe/Vienna]", "named, with ! and no offset"],
+  ["12:34:56.987654321[+00:00]", "numeric, with no offset"],
+  ["12:34:56.987654321[!-02:30]", "numeric, with ! and no offset"],
+  ["T12:34:56.987654321[UTC]", "named, with T and no offset"],
+  ["T12:34:56.987654321[!Africa/Abidjan]", "named, with T, !, and no offset"],
+  ["T12:34:56.987654321[+01:00]", "numeric, with T and no offset"],
+  ["T12:34:56.987654321[!-08:00]", "numeric, with T, !, and no offset"],
+  ["12:34:56.987654321+00:00[America/Sao_Paulo]", "named, with offset"],
+  ["12:34:56.987654321+00:00[!Asia/Tokyo]", "named, with ! and offset"],
+  ["12:34:56.987654321+00:00[-02:30]", "numeric, with offset"],
+  ["12:34:56.987654321+00:00[!+00:00]", "numeric, with ! and offset"],
+  ["T12:34:56.987654321+00:00[America/New_York]", "named, with T and offset"],
+  ["T12:34:56.987654321+00:00[!UTC]", "named, with T, !, and offset"],
+  ["T12:34:56.987654321+00:00[-08:00]", "numeric, with T and offset"],
+  ["T12:34:56.987654321+00:00[!+01:00]", "numeric, with T, !, and offset"],
+  ["1970-01-01T12:34:56.987654321[Africa/Lagos]", "named, with date and no offset"],
+  ["1970-01-01T12:34:56.987654321[!America/Vancouver]", "named, with date, !, and no offset"],
+  ["1970-01-01T12:34:56.987654321[+00:00]", "numeric, with date and no offset"],
+  ["1970-01-01T12:34:56.987654321[!-02:30]", "numeric, with date, !, and no offset"],
+  ["1970-01-01T12:34:56.987654321+00:00[Europe/London]", "named, with date and offset"],
+  ["1970-01-01T12:34:56.987654321+00:00[!Asia/Seoul]", "named, with date, offset, and !"],
+  ["1970-01-01T12:34:56.987654321+00:00[+01:00]", "numeric, with date and offset"],
+  ["1970-01-01T12:34:56.987654321+00:00[!-08:00]", "numeric, with date, offset, and !"],
+];
+
+tests.forEach(([arg, description]) => {
+  const result = Temporal.PlainTime.compare(arg, arg);
+
+  assert.sameValue(
+    result,
+    0,
+    `time zone annotation (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-unknown-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-unknown-annotation.js
new file mode 100644
index 0000000000..ad5ec5a158
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-unknown-annotation.js
@@ -0,0 +1,37 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: Various forms of unknown annotation
+features: [Temporal]
+---*/
+
+const tests = [
+  ["12:34:56.987654321[foo=bar]", "alone"],
+  ["12:34:56.987654321[UTC][foo=bar]", "with time zone"],
+  ["12:34:56.987654321[u-ca=iso8601][foo=bar]", "with calendar"],
+  ["12:34:56.987654321[UTC][foo=bar][u-ca=iso8601]", "with time zone and calendar"],
+  ["T12:34:56.987654321[foo=bar]", "with T"],
+  ["T12:34:56.987654321[UTC][foo=bar]", "with T and time zone"],
+  ["T12:34:56.987654321[u-ca=iso8601][foo=bar]", "with T and calendar"],
+  ["T12:34:56.987654321[UTC][foo=bar][u-ca=iso8601]", "with T, time zone, and calendar"],
+  ["1970-01-01T12:34:56.987654321[foo=bar]", "with date"],
+  ["1970-01-01T12:34:56.987654321[UTC][foo=bar]", "with date and time zone"],
+  ["1970-01-01T12:34:56.987654321[u-ca=iso8601][foo=bar]", "with date and calendar"],
+  ["1970-01-01T12:34:56.987654321[UTC][foo=bar][u-ca=iso8601]", "with date, time zone, and calendar"],
+  ["1970-01-01T12:34:56.987654321[foo=bar][_foo-bar0=Ignore-This-999999999999]", "with another unknown annotation"],
+];
+
+tests.forEach(([arg, description]) => {
+  const result = Temporal.PlainTime.compare(arg, arg);
+
+  assert.sameValue(
+    result,
+    0,
+    `unknown annotation (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-with-time-designator.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-with-time-designator.js
new file mode 100644
index 0000000000..78bc8e8a31
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-with-time-designator.js
@@ -0,0 +1,31 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: ISO 8601 time designator "T" allowed at the start of PlainTime strings
+features: [Temporal, arrow-function]
+---*/
+
+const halfPast = new Temporal.PlainTime(0, 30);
+const validStrings = [
+  "T00:30",
+  "t00:30",
+  "T0030",
+  "t0030",
+  "T00:30:00",
+  "t00:30:00",
+  "T003000",
+  "t003000",
+  "T00:30:00.000000000",
+  "t00:30:00.000000000",
+  "T003000.000000000",
+  "t003000.000000000",
+];
+validStrings.forEach((arg) => {
+  assert.sameValue(Temporal.PlainTime.compare(arg, halfPast), 0, `T prefix is accepted: ${arg} (first argument)`);
+  assert.sameValue(Temporal.PlainTime.compare(halfPast, arg), 0, `T prefix is accepted: ${arg} (second argument)`);
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-with-utc-designator.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-with-utc-designator.js
new file mode 100644
index 0000000000..ef9b3cae37
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-string-with-utc-designator.js
@@ -0,0 +1,29 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: RangeError thrown if a string with UTC designator is used as a PlainTime
+features: [Temporal, arrow-function]
+---*/
+
+const invalidStrings = [
+  "2019-10-01T09:00:00Z",
+  "2019-10-01T09:00:00Z[UTC]",
+];
+const plainTime = new Temporal.PlainTime();
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.compare(arg, plainTime),
+    "String with UTC designator should not be valid as a PlainTime (first argument)"
+  );
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.compare(plainTime, arg),
+    "String with UTC designator should not be valid as a PlainTime (second argument)"
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-wrong-type.js
new file mode 100644
index 0000000000..016ed3972d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-wrong-type.js
@@ -0,0 +1,39 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: >
+  Appropriate error thrown when argument cannot be converted to a valid string
+  or property bag for PlainTime
+features: [BigInt, Symbol, Temporal]
+---*/
+
+const rangeErrorTests = [
+  [undefined, "undefined"],
+  [null, "null"],
+  [true, "boolean"],
+  ["", "empty string"],
+  [1, "number that doesn't convert to a valid ISO string"],
+  [1n, "bigint"],
+];
+
+for (const [arg, description] of rangeErrorTests) {
+  assert.throws(RangeError, () => Temporal.PlainTime.compare(arg, new Temporal.PlainTime(12, 34, 56, 987, 654, 321)), `${description} does not convert to a valid ISO string (first argument)`);
+  assert.throws(RangeError, () => Temporal.PlainTime.compare(new Temporal.PlainTime(12, 34, 56, 987, 654, 321), arg), `${description} does not convert to a valid ISO string (second argument)`);
+}
+
+const typeErrorTests = [
+  [Symbol(), "symbol"],
+  [{}, "plain object"],
+  [Temporal.PlainTime, "Temporal.PlainTime, object"],
+  [Temporal.PlainTime.prototype, "Temporal.PlainTime.prototype, object"],
+];
+
+for (const [arg, description] of typeErrorTests) {
+  assert.throws(TypeError, () => Temporal.PlainTime.compare(arg, new Temporal.PlainTime(12, 34, 56, 987, 654, 321)), `${description} is not a valid property bag and does not convert to a string (first argument)`);
+  assert.throws(TypeError, () => Temporal.PlainTime.compare(new Temporal.PlainTime(12, 34, 56, 987, 654, 321), arg), `${description} is not a valid property bag and does not convert to a string (second argument)`);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-zoneddatetime-negative-epochnanoseconds.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-zoneddatetime-negative-epochnanoseconds.js
new file mode 100644
index 0000000000..5ef86caf22
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-zoneddatetime-negative-epochnanoseconds.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: A pre-epoch value is handled correctly by the modulo operation in GetISOPartsFromEpoch
+info: |
+    sec-temporal-getisopartsfromepoch step 1:
+      1. Let _remainderNs_ be the mathematical value whose sign is the sign of _epochNanoseconds_ and whose magnitude is abs(_epochNanoseconds_) modulo 10<sup>6</sup>.
+    sec-temporal-builtintimezonegetplaindatetimefor step 2:
+      2. Let _result_ be ! GetISOPartsFromEpoch(_instant_.[[Nanoseconds]]).
+features: [Temporal]
+---*/
+
+const datetime = new Temporal.ZonedDateTime(-13849764_999_999_999n, "UTC");
+const time = new Temporal.PlainTime(16, 50, 35, 0, 0, 1);
+
+// This code path shows up anywhere we convert an exact time, before the Unix
+// epoch, with nonzero microseconds or nanoseconds, into a wall time.
+
+const result1 = Temporal.PlainTime.compare(time, datetime);
+assert.sameValue(result1, 0);
+
+const result2 = Temporal.PlainTime.compare(datetime, time);
+assert.sameValue(result2, 0);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-non-integer.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-non-integer.js
new file mode 100644
index 0000000000..b5f95f205f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-non-integer.js
@@ -0,0 +1,21 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: RangeError thrown if time zone reports an offset that is not an integer number of nanoseconds
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[3600_000_000_000.5, NaN, Infinity, -Infinity].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+  assert.throws(RangeError, () => Temporal.PlainTime.compare(datetime, time));
+  assert.throws(RangeError, () => Temporal.PlainTime.compare(time, datetime));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js
new file mode 100644
index 0000000000..f183a46fea
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: TypeError thrown if timeZone.getOffsetNanosecondsFor is not callable
+features: [BigInt, Symbol, Temporal, arrow-function]
+---*/
+
+[undefined, null, true, Math.PI, 'string', Symbol('sym'), 42n, {}].forEach((notCallable) => {
+  const timeZone = new Temporal.TimeZone("UTC");
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  timeZone.getOffsetNanosecondsFor = notCallable;
+  assert.throws(
+    TypeError,
+    () => Temporal.PlainTime.compare(datetime, time),
+    `Uncallable ${notCallable === null ? 'null' : typeof notCallable} getOffsetNanosecondsFor should throw TypeError`
+  );
+  assert.throws(
+    TypeError,
+    () => Temporal.PlainTime.compare(time, datetime),
+    `Uncallable ${notCallable === null ? 'null' : typeof notCallable} getOffsetNanosecondsFor should throw TypeError`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-out-of-range.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-out-of-range.js
new file mode 100644
index 0000000000..da01ee93a6
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-out-of-range.js
@@ -0,0 +1,21 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: RangeError thrown if time zone reports an offset that is out of range
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[-86400_000_000_001, 86400_000_000_001].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+  assert.throws(RangeError, () => Temporal.PlainTime.compare(datetime, time));
+  assert.throws(RangeError, () => Temporal.PlainTime.compare(time, datetime));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-wrong-type.js
new file mode 100644
index 0000000000..366f7025d9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-wrong-type.js
@@ -0,0 +1,30 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: TypeError thrown if time zone reports an offset that is not a Number
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[
+  undefined,
+  null,
+  true,
+  "+01:00",
+  Symbol(),
+  3600_000_000_000n,
+  {},
+  { valueOf() { return 3600_000_000_000; } },
+].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+  assert.throws(TypeError, () => Temporal.PlainTime.compare(datetime, time));
+  assert.throws(TypeError, () => Temporal.PlainTime.compare(time, datetime));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/basic.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/basic.js
new file mode 100644
index 0000000000..054f7aa4cd
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/basic.js
@@ -0,0 +1,20 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: Basic tests for compare()
+features: [Temporal]
+---*/
+
+const t1 = Temporal.PlainTime.from("08:44:15.321");
+const t1bis = Temporal.PlainTime.from("08:44:15.321");
+const t2 = Temporal.PlainTime.from("14:23:30.123");
+
+assert.sameValue(Temporal.PlainTime.compare(t1, t1), 0, "same object");
+assert.sameValue(Temporal.PlainTime.compare(t1, t1bis), 0, "different object");
+assert.sameValue(Temporal.PlainTime.compare(t1, t2), -1, "before");
+assert.sameValue(Temporal.PlainTime.compare(t2, t1), 1, "after");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/builtin.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/builtin.js
new file mode 100644
index 0000000000..9df7635369
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/builtin.js
@@ -0,0 +1,33 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: Tests that Temporal.PlainTime.compare meets the requirements for built-in objects
+info: |
+    Built-in functions that are not constructors do not have a "prototype" property unless
+    otherwise specified in the description of a particular function.
+
+    Unless specified otherwise, a built-in object that is callable as a function is a built-in
+    function object with the characteristics described in 10.3. Unless specified otherwise, the
+    [[Extensible]] internal slot of a built-in object initially has the value true.
+
+    Unless otherwise specified every built-in function and every built-in constructor has the
+    Function prototype object [...] as the value of its [[Prototype]] internal slot.
+features: [Temporal]
+---*/
+
+assert.sameValue(Object.isExtensible(Temporal.PlainTime.compare),
+  true, "Built-in objects must be extensible.");
+
+assert.sameValue(Object.prototype.toString.call(Temporal.PlainTime.compare),
+  "[object Function]", "Object.prototype.toString");
+
+assert.sameValue(Object.getPrototypeOf(Temporal.PlainTime.compare),
+  Function.prototype, "prototype");
+
+assert.sameValue(Temporal.PlainTime.compare.hasOwnProperty("prototype"),
+  false, "prototype property");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/calendar-temporal-object.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/calendar-temporal-object.js
new file mode 100644
index 0000000000..97cb9eae3d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/calendar-temporal-object.js
@@ -0,0 +1,30 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: Fast path for converting other Temporal objects to Temporal.Calendar by reading internal slots
+info: |
+    sec-temporal.plaintime.compare steps 1–2:
+      1. Set _one_ to ? ToTemporalTime(_one_).
+      2. Set _two_ to ? ToTemporalTime(_two_).
+    sec-temporal-totemporaltime step 3.d:
+      d. If _calendar_ is not *undefined*, then
+        i. Set _calendar_ to ? ToTemporalCalendar(_calendar_).
+        ii. If ? ToString(_calendar_) is not *"iso8601"*, then
+          1. Throw a *RangeError* exception.
+    sec-temporal-totemporalcalendar step 1.a:
+      a. If _temporalCalendarLike_ has an [[InitializedTemporalDate]], [[InitializedTemporalDateTime]], [[InitializedTemporalMonthDay]], [[InitializedTemporalYearMonth]], or [[InitializedTemporalZonedDateTime]] internal slot, then
+        i. Return _temporalCalendarLike_.[[Calendar]].
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+TemporalHelpers.checkToTemporalCalendarFastPath((temporalObject) => {
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  assert.throws(RangeError, () => Temporal.PlainTime.compare({ hour: 12, minute: 30, calendar: temporalObject }, time));
+  assert.throws(RangeError, () => Temporal.PlainTime.compare(time, { hour: 12, minute: 30, calendar: temporalObject }));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/leap-second.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/leap-second.js
new file mode 100644
index 0000000000..9a7ad7be2a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/leap-second.js
@@ -0,0 +1,23 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: Leap second is a valid ISO string for PlainTime
+features: [Temporal]
+---*/
+
+let arg = "2016-12-31T23:59:60";
+const result1 = Temporal.PlainTime.compare(arg, new Temporal.PlainTime(23, 59, 59));
+assert.sameValue(result1, 0, "leap second is a valid ISO string for PlainTime (first argument)");
+const result2 = Temporal.PlainTime.compare(new Temporal.PlainTime(23, 59, 59), arg);
+assert.sameValue(result2, 0, "leap second is a valid ISO string for PlainTime (first argument)");
+
+arg = { year: 2016, month: 12, day: 31, hour: 23, minute: 59, second: 60 };
+const result3 = Temporal.PlainTime.compare(arg, new Temporal.PlainTime(23, 59, 59));
+assert.sameValue(result3, 0, "second: 60 is ignored in property bag for PlainTime (first argument)");
+const result4 = Temporal.PlainTime.compare(new Temporal.PlainTime(23, 59, 59), arg);
+assert.sameValue(result4, 0, "second: 60 is ignored in property bag for PlainTime (second argument)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/length.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/length.js
new file mode 100644
index 0000000000..a49280dcaf
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/length.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: Temporal.PlainTime.compare.length is 2
+info: |
+    Every built-in function object, including constructors, has a "length" property whose value is
+    an integer. Unless otherwise specified, this value is equal to the largest number of named
+    arguments shown in the subclause headings for the function description. Optional parameters
+    (which are indicated with brackets: [ ]) or rest parameters (which are shown using the form
+    «...name») are not included in the default argument count.
+
+    Unless otherwise specified, the "length" property of a built-in function object has the
+    attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.compare, "length", {
+  value: 2,
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/name.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/name.js
new file mode 100644
index 0000000000..9ca4422b8d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/name.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: Temporal.PlainTime.compare.name is "compare"
+info: |
+    Every built-in function object, including constructors, that is not identified as an anonymous
+    function has a "name" property whose value is a String. Unless otherwise specified, this value
+    is the name that is given to the function in this specification.
+
+    Unless otherwise specified, the "name" property of a built-in function object, if it exists,
+    has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.compare, "name", {
+  value: "compare",
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/not-a-constructor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/not-a-constructor.js
new file mode 100644
index 0000000000..bdd9aaf583
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/not-a-constructor.js
@@ -0,0 +1,23 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: Temporal.PlainTime.compare does not implement [[Construct]], is not new-able
+info: |
+    Built-in function objects that are not identified as constructors do not implement the
+    [[Construct]] internal method unless otherwise specified in the description of a particular
+    function.
+includes: [isConstructor.js]
+features: [Reflect.construct, Temporal]
+---*/
+
+assert.throws(TypeError, () => {
+  new Temporal.PlainTime.compare();
+}, "Calling as constructor");
+
+assert.sameValue(isConstructor(Temporal.PlainTime.compare), false,
+  "isConstructor(Temporal.PlainTime.compare)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/plaintime-propertybag-no-time-units.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/plaintime-propertybag-no-time-units.js
new file mode 100644
index 0000000000..ae9cc0df65
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/plaintime-propertybag-no-time-units.js
@@ -0,0 +1,18 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: Missing time units in property bag default to 0
+features: [Temporal]
+---*/
+
+const props = {};
+assert.throws(TypeError, () => Temporal.PlainTime.compare(props, new Temporal.PlainTime(0, 30)), "TypeError if no properties are present");
+
+props.minute = 30;
+const result = Temporal.PlainTime.compare(props, new Temporal.PlainTime(0, 30));
+assert.sameValue(result, 0, "missing time units default to 0");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/prop-desc.js
new file mode 100644
index 0000000000..51c83d239b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/prop-desc.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: The "compare" property of Temporal.PlainTime
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+assert.sameValue(
+  typeof Temporal.PlainTime.compare,
+  "function",
+  "`typeof PlainTime.compare` is `function`"
+);
+
+verifyProperty(Temporal.PlainTime, "compare", {
+  writable: true,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/use-internal-slots.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/use-internal-slots.js
new file mode 100644
index 0000000000..c430217b1c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/use-internal-slots.js
@@ -0,0 +1,38 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal-comparetemporaltime
+description: compare() ignores the observable properties and uses internal slots
+features: [Temporal]
+---*/
+
+function CustomError() {}
+
+class AvoidGettersTime extends Temporal.PlainTime {
+  get hour() {
+    throw new CustomError();
+  }
+  get minute() {
+    throw new CustomError();
+  }
+  get second() {
+    throw new CustomError();
+  }
+  get millisecond() {
+    throw new CustomError();
+  }
+  get microsecond() {
+    throw new CustomError();
+  }
+  get nanosecond() {
+    throw new CustomError();
+  }
+}
+
+const one = new AvoidGettersTime(12, 34, 56, 987, 654, 321);
+const two = new AvoidGettersTime(6, 54, 32, 123, 456, 789);
+assert.sameValue(Temporal.PlainTime.compare(one, two), 1);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/year-zero.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/year-zero.js
new file mode 100644
index 0000000000..bbc04351af
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/compare/year-zero.js
@@ -0,0 +1,32 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.compare
+description: Negative zero, as an extended year, fails
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+const invalidStrings = [
+  "-000000-12-07T03:24:30",
+  "-000000-12-07T03:24:30+01:00",
+  "-000000-12-07T03:24:30+00:00[UTC]",
+];
+
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.compare(arg, time),
+    "Cannot use minus zero as extended year (first argument)"
+  );
+
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.compare(time, arg),
+    "Cannot use minus zero as extended year (second argument)"
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/constructor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/constructor.js
new file mode 100644
index 0000000000..0ec038cfeb
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/constructor.js
@@ -0,0 +1,15 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime
+description: Temporal.PlainTime constructor cannot be called as a function
+info: |
+    1. If NewTarget is undefined, throw a TypeError exception.
+features: [Temporal]
+---*/
+
+assert.throws(TypeError, () => Temporal.PlainTime(12, 0, 0));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-number.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-number.js
new file mode 100644
index 0000000000..35fc5780b5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-number.js
@@ -0,0 +1,32 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: A number is converted to a string, then to Temporal.PlainTime
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const arg = 123456.987654321;
+
+const result = Temporal.PlainTime.from(arg);
+TemporalHelpers.assertPlainTime(result, 12, 34, 56, 987, 654, 321, "123456.987654321 is a valid ISO string for PlainTime");
+
+const numbers = [
+  1,
+  -123456.987654321,
+  1234567,
+  123456.9876543219,
+];
+
+for (const arg of numbers) {
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.from(arg),
+    `Number ${arg} does not convert to a valid ISO string for PlainTime`
+  );
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-object-leap-second.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-object-leap-second.js
new file mode 100644
index 0000000000..a0a045c4d5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-object-leap-second.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: Object argument handles leap seconds according to the overflow option.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+for (const options of [undefined, {}, { overflow: "constrain" }]) {
+  TemporalHelpers.assertPlainTime(Temporal.PlainTime.from({ hour: 23, minute: 59, second: 60 }, options),
+    23, 59, 59, 0, 0, 0);
+  TemporalHelpers.assertPlainTime(Temporal.PlainTime.from({ hour: 12, minute: 30, second: 60 }, options),
+    12, 30, 59, 0, 0, 0);
+  TemporalHelpers.assertPlainTime(Temporal.PlainTime.from({ hour: 23, minute: 59, second: 60, millisecond: 170 }, options),
+    23, 59, 59, 170, 0, 0);
+}
+
+const options = { overflow: "reject" };
+assert.throws(RangeError, () => Temporal.PlainTime.from({ hour: 23, minute: 59, second: 60 }, options));
+assert.throws(RangeError, () => Temporal.PlainTime.from({ hour: 12, minute: 30, second: 60 }, options));
+assert.throws(RangeError, () => Temporal.PlainTime.from({ hour: 23, minute: 59, second: 60, millisecond: 170 }, options));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-object.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-object.js
new file mode 100644
index 0000000000..f02a090c34
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-object.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: Plain object argument is supported and ignores plural properties
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+TemporalHelpers.assertPlainTime(Temporal.PlainTime.from({ hour: 15, minute: 23 }),
+  15, 23, 0, 0, 0, 0);
+TemporalHelpers.assertPlainTime(Temporal.PlainTime.from({ minute: 30, microsecond: 555 }),
+  0, 30, 0, 0, 555, 0);
+TemporalHelpers.assertPlainTime(Temporal.PlainTime.from({ year: 2019, month: 10, day: 1, hour: 14, minute: 20, second: 36 }),
+  14, 20, 36, 0, 0, 0);
+TemporalHelpers.assertPlainTime(Temporal.PlainTime.from({ hours: 2, minute: 30, microsecond: 555 }),
+  0, 30, 0, 0, 555, 0);
+
+assert.throws(TypeError, () => Temporal.PlainTime.from({}));
+assert.throws(TypeError, () => Temporal.PlainTime.from({ minutes: 12 }));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-plaindatetime.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-plaindatetime.js
new file mode 100644
index 0000000000..55cf869a26
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-plaindatetime.js
@@ -0,0 +1,17 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: Fast path for converting Temporal.PlainDateTime to Temporal.PlainTime by reading internal slots
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+TemporalHelpers.checkPlainDateTimeConversionFastPath((plainDateTime) => {
+  const result = Temporal.PlainTime.from(plainDateTime);
+  TemporalHelpers.assertPlainTime(result, 12, 34, 56, 987, 654, 321);
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-plaintime.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-plaintime.js
new file mode 100644
index 0000000000..65b4b40792
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-plaintime.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: A PlainTime object is copied, not returned directly
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const orig = new Temporal.PlainTime(11, 42, 0, 0, 0, 0);
+const result = Temporal.PlainTime.from(orig);
+
+TemporalHelpers.assertPlainTime(
+  result,
+  11, 42, 0, 0, 0, 0,
+  "PlainTime is copied"
+);
+
+assert.notSameValue(
+  result,
+  orig,
+  "When a PlainTime is given, the returned value is not the original PlainTime"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-calendar-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-calendar-annotation.js
new file mode 100644
index 0000000000..7bd0468a33
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-calendar-annotation.js
@@ -0,0 +1,39 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: Various forms of calendar annotation; critical flag has no effect
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const tests = [
+  ["12:34:56.987654321[u-ca=iso8601]", "without time zone"],
+  ["12:34:56.987654321[UTC][u-ca=iso8601]", "with time zone"],
+  ["12:34:56.987654321[!u-ca=iso8601]", "with ! and no time zone"],
+  ["12:34:56.987654321[UTC][!u-ca=iso8601]", "with ! and time zone"],
+  ["T12:34:56.987654321[u-ca=iso8601]", "with T and no time zone"],
+  ["T12:34:56.987654321[UTC][u-ca=iso8601]", "with T and time zone"],
+  ["T12:34:56.987654321[!u-ca=iso8601]", "with T, !, and no time zone"],
+  ["T12:34:56.987654321[UTC][!u-ca=iso8601]", "with T, !, and time zone"],
+  ["1970-01-01T12:34:56.987654321[u-ca=iso8601]", "with date and no time zone"],
+  ["1970-01-01T12:34:56.987654321[UTC][u-ca=iso8601]", "with date and time zone"],
+  ["1970-01-01T12:34:56.987654321[!u-ca=iso8601]", "with !, date, and no time zone"],
+  ["1970-01-01T12:34:56.987654321[UTC][!u-ca=iso8601]", "with !, date, and time zone"],
+  ["1970-01-01T12:34:56.987654321[u-ca=iso8601][u-ca=discord]", "second annotation ignored"],
+  ["1970-01-01T12:34:56.987654321[u-ca=iso8601][!u-ca=discord]", "second annotation ignored even with !"],
+];
+
+tests.forEach(([arg, description]) => {
+  const result = Temporal.PlainTime.from(arg);
+
+  TemporalHelpers.assertPlainTime(
+    result,
+    12, 34, 56, 987, 654, 321,
+    `calendar annotation (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-critical-unknown-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-critical-unknown-annotation.js
new file mode 100644
index 0000000000..63aaa5eb8e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-critical-unknown-annotation.js
@@ -0,0 +1,29 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: Unknown annotations with critical flag are rejected
+features: [Temporal]
+---*/
+
+const invalidStrings = [
+  "00:00[!foo=bar]",
+  "T00:00[!foo=bar]",
+  "1970-01-01T00:00[!foo=bar]",
+  "1970-01-01T00:00[UTC][!foo=bar]",
+  "1970-01-01T00:00[u-ca=iso8601][!foo=bar]",
+  "1970-01-01T00:00[UTC][!foo=bar][u-ca=iso8601]",
+  "1970-01-01T00:00[foo=bar][!_foo-bar0=Dont-Ignore-This-99999999999]",
+];
+
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.from(arg),
+    `reject unknown annotation with critical flag: ${arg}`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-date-with-utc-offset.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-date-with-utc-offset.js
new file mode 100644
index 0000000000..6143f3c548
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-date-with-utc-offset.js
@@ -0,0 +1,51 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: UTC offset not valid with format that does not include a time
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const validStrings = [
+  "12:34:56.987654321+00:00",
+  "12:34:56.987654321+00:00[UTC]",
+  "12:34:56.987654321+00:00[!UTC]",
+  "12:34:56.987654321-02:30[America/St_Johns]",
+  "1976-11-18T12:34:56.987654321+00:00",
+  "1976-11-18T12:34:56.987654321+00:00[UTC]",
+  "1976-11-18T12:34:56.987654321+00:00[!UTC]",
+  "1976-11-18T12:34:56.987654321-02:30[America/St_Johns]",
+];
+
+for (const arg of validStrings) {
+  const result = Temporal.PlainTime.from(arg);
+
+  TemporalHelpers.assertPlainTime(
+    result,
+    12, 34, 56, 987, 654, 321,
+    `"${arg}" is a valid UTC offset with time for PlainTime`
+  );
+}
+
+const invalidStrings = [
+  "2022-09-15Z",
+  "2022-09-15Z[UTC]",
+  "2022-09-15Z[Europe/Vienna]",
+  "2022-09-15+00:00",
+  "2022-09-15+00:00[UTC]",
+  "2022-09-15-02:30",
+  "2022-09-15-02:30[America/St_Johns]",
+];
+
+for (const arg of invalidStrings) {
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.from(arg),
+    `"${arg}" UTC offset without time is not valid for PlainTime`
+  );
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-leap-second.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-leap-second.js
new file mode 100644
index 0000000000..f64a291ee3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-leap-second.js
@@ -0,0 +1,21 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: Leap second is replaced by :59 in ISO strings.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+for (const options of [undefined, {}, { overflow: "constrain" }, { overflow: "reject" }]) {
+  TemporalHelpers.assertPlainTime(Temporal.PlainTime.from("23:59:60", options),
+    23, 59, 59, 0, 0, 0);
+  TemporalHelpers.assertPlainTime(Temporal.PlainTime.from("12:30:60", options),
+    12, 30, 59, 0, 0, 0);
+  TemporalHelpers.assertPlainTime(Temporal.PlainTime.from("23:59:60.170", options),
+    23, 59, 59, 170, 0, 0);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-multiple-time-zone.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-multiple-time-zone.js
new file mode 100644
index 0000000000..bea0a42176
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-multiple-time-zone.js
@@ -0,0 +1,29 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: More than one time zone annotation is not syntactical
+features: [Temporal]
+---*/
+
+const invalidStrings = [
+  "00:00[UTC][UTC]",
+  "T00:00[UTC][UTC]",
+  "1970-01-01T00:00[UTC][UTC]",
+  "1970-01-01T00:00[!UTC][UTC]",
+  "1970-01-01T00:00[UTC][!UTC]",
+  "1970-01-01T00:00[UTC][u-ca=iso8601][UTC]",
+  "1970-01-01T00:00[UTC][foo=bar][UTC]",
+];
+
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.from(arg),
+    `reject more than one time zone annotation: ${arg}`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-no-implicit-midnight.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-no-implicit-midnight.js
new file mode 100644
index 0000000000..7269411e5a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-no-implicit-midnight.js
@@ -0,0 +1,18 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: RangeError thrown if a date-only string is passed in a PlainTime context
+features: [Temporal, arrow-function]
+---*/
+
+const arg = "2019-10-01";
+assert.throws(
+  RangeError,
+  () => Temporal.PlainTime.from(arg),
+  "Date-only string throws, does not implicitly convert to midnight"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-time-designator-required-for-disambiguation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-time-designator-required-for-disambiguation.js
new file mode 100644
index 0000000000..cb23ef01ac
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-time-designator-required-for-disambiguation.js
@@ -0,0 +1,35 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: ISO 8601 time designator "T" required in cases of ambiguity
+includes: [temporalHelpers.js]
+features: [Temporal, arrow-function]
+---*/
+
+TemporalHelpers.ISO.plainTimeStringsAmbiguous().forEach((string) => {
+  let arg = string;
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.from(arg),
+    `'${arg}' is ambiguous and requires T prefix`
+  );
+  // The same string with a T prefix should not throw:
+  arg = `T${string}`;
+  Temporal.PlainTime.from(arg);
+
+  arg = ` ${string}`;
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.from(arg),
+    `space is not accepted as a substitute for T prefix: '${arg}'`
+  );
+});
+
+// None of these should throw without a T prefix, because they are unambiguously time strings:
+TemporalHelpers.ISO.plainTimeStringsUnambiguous().forEach(
+  (arg) => Temporal.PlainTime.from(arg));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-time-separators.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-time-separators.js
new file mode 100644
index 0000000000..64d3d2727c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-time-separators.js
@@ -0,0 +1,30 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: Time separator in string argument can vary
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const tests = [
+  ["1976-11-18T12:34:56.987654321", "uppercase T"],
+  ["1976-11-18t12:34:56.987654321", "lowercase T"],
+  ["1976-11-18 12:34:56.987654321", "space between date and time"],
+  ["T12:34:56.987654321", "time-only uppercase T"],
+  ["t12:34:56.987654321", "time-only lowercase T"],
+];
+
+tests.forEach(([arg, description]) => {
+  const result = Temporal.PlainTime.from(arg);
+
+  TemporalHelpers.assertPlainTime(
+    result,
+    12, 34, 56, 987, 654, 321,
+    `variant time separators (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-time-zone-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-time-zone-annotation.js
new file mode 100644
index 0000000000..9227afbcab
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-time-zone-annotation.js
@@ -0,0 +1,49 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: Various forms of time zone annotation; critical flag has no effect
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const tests = [
+  ["12:34:56.987654321[Asia/Kolkata]", "named, with no offset"],
+  ["12:34:56.987654321[!Europe/Vienna]", "named, with ! and no offset"],
+  ["12:34:56.987654321[+00:00]", "numeric, with no offset"],
+  ["12:34:56.987654321[!-02:30]", "numeric, with ! and no offset"],
+  ["T12:34:56.987654321[UTC]", "named, with T and no offset"],
+  ["T12:34:56.987654321[!Africa/Abidjan]", "named, with T, !, and no offset"],
+  ["T12:34:56.987654321[+01:00]", "numeric, with T and no offset"],
+  ["T12:34:56.987654321[!-08:00]", "numeric, with T, !, and no offset"],
+  ["12:34:56.987654321+00:00[America/Sao_Paulo]", "named, with offset"],
+  ["12:34:56.987654321+00:00[!Asia/Tokyo]", "named, with ! and offset"],
+  ["12:34:56.987654321+00:00[-02:30]", "numeric, with offset"],
+  ["12:34:56.987654321+00:00[!+00:00]", "numeric, with ! and offset"],
+  ["T12:34:56.987654321+00:00[America/New_York]", "named, with T and offset"],
+  ["T12:34:56.987654321+00:00[!UTC]", "named, with T, !, and offset"],
+  ["T12:34:56.987654321+00:00[-08:00]", "numeric, with T and offset"],
+  ["T12:34:56.987654321+00:00[!+01:00]", "numeric, with T, !, and offset"],
+  ["1970-01-01T12:34:56.987654321[Africa/Lagos]", "named, with date and no offset"],
+  ["1970-01-01T12:34:56.987654321[!America/Vancouver]", "named, with date, !, and no offset"],
+  ["1970-01-01T12:34:56.987654321[+00:00]", "numeric, with date and no offset"],
+  ["1970-01-01T12:34:56.987654321[!-02:30]", "numeric, with date, !, and no offset"],
+  ["1970-01-01T12:34:56.987654321+00:00[Europe/London]", "named, with date and offset"],
+  ["1970-01-01T12:34:56.987654321+00:00[!Asia/Seoul]", "named, with date, offset, and !"],
+  ["1970-01-01T12:34:56.987654321+00:00[+01:00]", "numeric, with date and offset"],
+  ["1970-01-01T12:34:56.987654321+00:00[!-08:00]", "numeric, with date, offset, and !"],
+];
+
+tests.forEach(([arg, description]) => {
+  const result = Temporal.PlainTime.from(arg);
+
+  TemporalHelpers.assertPlainTime(
+    result,
+    12, 34, 56, 987, 654, 321,
+    `time zone annotation (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-trailing-junk.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-trailing-junk.js
new file mode 100644
index 0000000000..847f9ae138
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-trailing-junk.js
@@ -0,0 +1,14 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: RangeError thrown if a string argument has trailing junk
+features: [Temporal, arrow-function]
+---*/
+
+const arg = "15:23:30.100junk";
+assert.throws(RangeError, () => Temporal.PlainTime.from(arg));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-unknown-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-unknown-annotation.js
new file mode 100644
index 0000000000..0b972c128e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-unknown-annotation.js
@@ -0,0 +1,38 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: Various forms of unknown annotation
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const tests = [
+  ["12:34:56.987654321[foo=bar]", "alone"],
+  ["12:34:56.987654321[UTC][foo=bar]", "with time zone"],
+  ["12:34:56.987654321[u-ca=iso8601][foo=bar]", "with calendar"],
+  ["12:34:56.987654321[UTC][foo=bar][u-ca=iso8601]", "with time zone and calendar"],
+  ["T12:34:56.987654321[foo=bar]", "with T"],
+  ["T12:34:56.987654321[UTC][foo=bar]", "with T and time zone"],
+  ["T12:34:56.987654321[u-ca=iso8601][foo=bar]", "with T and calendar"],
+  ["T12:34:56.987654321[UTC][foo=bar][u-ca=iso8601]", "with T, time zone, and calendar"],
+  ["1970-01-01T12:34:56.987654321[foo=bar]", "with date"],
+  ["1970-01-01T12:34:56.987654321[UTC][foo=bar]", "with date and time zone"],
+  ["1970-01-01T12:34:56.987654321[u-ca=iso8601][foo=bar]", "with date and calendar"],
+  ["1970-01-01T12:34:56.987654321[UTC][foo=bar][u-ca=iso8601]", "with date, time zone, and calendar"],
+  ["1970-01-01T12:34:56.987654321[foo=bar][_foo-bar0=Ignore-This-999999999999]", "with another unknown annotation"],
+];
+
+tests.forEach(([arg, description]) => {
+  const result = Temporal.PlainTime.from(arg);
+
+  TemporalHelpers.assertPlainTime(
+    result,
+    12, 34, 56, 987, 654, 321,
+    `unknown annotation (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-with-calendar.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-with-calendar.js
new file mode 100644
index 0000000000..326fe1ef8b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-with-calendar.js
@@ -0,0 +1,38 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal-totemporaltime
+description: Strings with non-ISO calendars are not supported.
+info: |
+    b. Let result be ? ParseTemporalTimeString(string).
+    d. If result.[[Calendar]] is not one of undefined or "iso8601", then
+        i. Throw a RangeError exception.
+features: [Temporal]
+---*/
+
+const isoString = "2004-03-21T10:00:00";
+
+const valid = [
+  "",
+  "[u-ca=iso8601]",
+];
+
+for (const s of valid) {
+  const input = isoString + s;
+  const plainTime = Temporal.PlainTime.from(input);
+  assert.sameValue(plainTime.calendar.id, "iso8601");
+}
+
+const invalid = [
+  "[u-ca=indian]",
+  "[u-ca=hebrew]",
+];
+
+for (const s of invalid) {
+  const input = isoString + s;
+  assert.throws(RangeError, () => Temporal.PlainTime.from(input));
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-with-time-designator.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-with-time-designator.js
new file mode 100644
index 0000000000..a693dc7806
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-with-time-designator.js
@@ -0,0 +1,31 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: ISO 8601 time designator "T" allowed at the start of PlainTime strings
+includes: [temporalHelpers.js]
+features: [Temporal, arrow-function]
+---*/
+
+const validStrings = [
+  "T00:30",
+  "t00:30",
+  "T0030",
+  "t0030",
+  "T00:30:00",
+  "t00:30:00",
+  "T003000",
+  "t003000",
+  "T00:30:00.000000000",
+  "t00:30:00.000000000",
+  "T003000.000000000",
+  "t003000.000000000",
+];
+validStrings.forEach((arg) => {
+  const result = Temporal.PlainTime.from(arg);
+  TemporalHelpers.assertPlainTime(result, 0, 30, 0, 0, 0, 0, `T prefix is accepted: ${arg}`);
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-with-utc-designator.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-with-utc-designator.js
new file mode 100644
index 0000000000..9597cc3b3a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string-with-utc-designator.js
@@ -0,0 +1,23 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: RangeError thrown if a string with UTC designator is used as a PlainTime
+features: [Temporal, arrow-function]
+---*/
+
+const invalidStrings = [
+  "2019-10-01T09:00:00Z",
+  "2019-10-01T09:00:00Z[UTC]",
+];
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.from(arg),
+    "String with UTC designator should not be valid as a PlainTime"
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string.js
new file mode 100644
index 0000000000..c1f4bc0d58
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-string.js
@@ -0,0 +1,60 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: Various ISO strings supported
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const tests = [
+  ["15:23", 15, 23, 0, 0, 0, 0],
+  ["15:23:30", 15, 23, 30, 0, 0, 0],
+  ["15:23:30.123", 15, 23, 30, 123, 0, 0],
+  ["15:23:30.123456", 15, 23, 30, 123, 456, 0],
+  ["15:23:30.123456789", 15, 23, 30, 123, 456, 789],
+  ["1976-11-18T15:23:30.1", 15, 23, 30, 100, 0, 0],
+  ["1976-11-18T15:23:30.12", 15, 23, 30, 120, 0, 0],
+  ["1976-11-18T15:23:30.123", 15, 23, 30, 123, 0, 0],
+  ["1976-11-18T15:23:30.1234", 15, 23, 30, 123, 400, 0],
+  ["1976-11-18T15:23:30.12345", 15, 23, 30, 123, 450, 0],
+  ["1976-11-18T15:23:30.123456", 15, 23, 30, 123, 456, 0],
+  ["1976-11-18T15:23:30.1234567", 15, 23, 30, 123, 456, 700],
+  ["1976-11-18T15:23:30.12345678", 15, 23, 30, 123, 456, 780],
+  ["1976-11-18T15:23:30.123456789", 15, 23, 30, 123, 456, 789],
+  ["1976-11-18T15:23:30,12", 15, 23, 30, 120, 0, 0],
+  ["1976-11-18T15:23:30.12\u221202:00", 15, 23, 30, 120, 0, 0],
+  ["152330", 15, 23, 30, 0, 0, 0],
+  ["152330.1", 15, 23, 30, 100, 0, 0],
+  ["152330-08", 15, 23, 30, 0, 0, 0],
+  ["152330.1-08", 15, 23, 30, 100, 0, 0],
+  ["152330-0800", 15, 23, 30, 0, 0, 0],
+  ["152330.1-0800", 15, 23, 30, 100, 0, 0],
+  ["1976-11-18T152330.1+00:00", 15, 23, 30, 100, 0, 0],
+  ["19761118T15:23:30.1+00:00", 15, 23, 30, 100, 0, 0],
+  ["1976-11-18T15:23:30.1+0000", 15, 23, 30, 100, 0, 0],
+  ["1976-11-18T152330.1+0000", 15, 23, 30, 100, 0, 0],
+  ["19761118T15:23:30.1+0000", 15, 23, 30, 100, 0, 0],
+  ["19761118T152330.1+00:00", 15, 23, 30, 100, 0, 0],
+  ["19761118T152330.1+0000", 15, 23, 30, 100, 0, 0],
+  ["+001976-11-18T152330.1+00:00", 15, 23, 30, 100, 0, 0],
+  ["+0019761118T15:23:30.1+00:00", 15, 23, 30, 100, 0, 0],
+  ["+001976-11-18T15:23:30.1+0000", 15, 23, 30, 100, 0, 0],
+  ["+001976-11-18T152330.1+0000", 15, 23, 30, 100, 0, 0],
+  ["+0019761118T15:23:30.1+0000", 15, 23, 30, 100, 0, 0],
+  ["+0019761118T152330.1+00:00", 15, 23, 30, 100, 0, 0],
+  ["+0019761118T152330.1+0000", 15, 23, 30, 100, 0, 0],
+  ["15", 15, 0, 0, 0, 0, 0],
+  ["T15:23:30", 15, 23, 30, 0, 0, 0],
+  ["t152330", 15, 23, 30, 0, 0, 0],
+];
+
+for (const [input, ...expected] of tests) {
+  const result = Temporal.PlainTime.from(input);
+  assert.sameValue(expected.length, 6, input);
+  TemporalHelpers.assertPlainTime(result, ...expected, input);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-wrong-type.js
new file mode 100644
index 0000000000..7878ec5759
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-wrong-type.js
@@ -0,0 +1,37 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: >
+  Appropriate error thrown when argument cannot be converted to a valid string
+  or property bag for PlainTime
+features: [BigInt, Symbol, Temporal]
+---*/
+
+const rangeErrorTests = [
+  [undefined, "undefined"],
+  [null, "null"],
+  [true, "boolean"],
+  ["", "empty string"],
+  [1, "number that doesn't convert to a valid ISO string"],
+  [1n, "bigint"],
+];
+
+for (const [arg, description] of rangeErrorTests) {
+  assert.throws(RangeError, () => Temporal.PlainTime.from(arg), `${description} does not convert to a valid ISO string`);
+}
+
+const typeErrorTests = [
+  [Symbol(), "symbol"],
+  [{}, "plain object"],
+  [Temporal.PlainTime, "Temporal.PlainTime, object"],
+  [Temporal.PlainTime.prototype, "Temporal.PlainTime.prototype, object"],
+];
+
+for (const [arg, description] of typeErrorTests) {
+  assert.throws(TypeError, () => Temporal.PlainTime.from(arg), `${description} is not a valid property bag and does not convert to a string`);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-zoneddatetime-balance-negative-time-units.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-zoneddatetime-balance-negative-time-units.js
new file mode 100644
index 0000000000..7674e13413
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-zoneddatetime-balance-negative-time-units.js
@@ -0,0 +1,46 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: Negative time fields are balanced upwards if the argument is given as ZonedDateTime
+info: |
+    sec-temporal-balancetime steps 3–14:
+      3. Set _microsecond_ to _microsecond_ + floor(_nanosecond_ / 1000).
+      4. Set _nanosecond_ to _nanosecond_ modulo 1000.
+      5. Set _millisecond_ to _millisecond_ + floor(_microsecond_ / 1000).
+      6. Set _microsecond_ to _microsecond_ modulo 1000.
+      7. Set _second_ to _second_ + floor(_millisecond_ / 1000).
+      8. Set _millisecond_ to _millisecond_ modulo 1000.
+      9. Set _minute_ to _minute_ + floor(_second_ / 60).
+      10. Set _second_ to _second_ modulo 60.
+      11. Set _hour_ to _hour_ + floor(_minute_ / 60).
+      12. Set _minute_ to _minute_ modulo 60.
+      13. Let _days_ be floor(_hour_ / 24).
+      14. Set _hour_ to _hour_ modulo 24.
+    sec-temporal-balanceisodatetime step 1:
+      1. Let _balancedTime_ be ? BalanceTime(_hour_, _minute_, _second_, _millisecond_, _microsecond_, _nanosecond_).
+    sec-temporal-builtintimezonegetplaindatetimefor step 3:
+      3. Set _result_ to ? BalanceISODateTime(_result_.[[Year]], _result_.[[Month]], _result_.[[Day]], _result_.[[Hour]], _result_.[[Minute]], _result_.[[Second]], _result_.[[Millisecond]], _result_.[[Microsecond]], _result_.[[Nanosecond]] + _offsetNanoseconds_).
+    sec-temporal-totemporaltime step 3.b:
+      b. If _item_ has an [[InitializedTemporalZonedDateTime]] internal slot, then
+        ...
+        ii. 1. Set _plainDateTime_ to ? BuiltinTimeZoneGetPlainDateTimeFor(_item_.[[TimeZone]], _instant_, _item_.[[Calendar]]).
+    sec-temporal.plaintime.from step 4:
+      4. Return ? ToTemporalTime(_temporalTime_).
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+// This code path is encountered if the time zone offset is negative and its
+// absolute value in nanoseconds is greater than the nanosecond field of the
+// exact time's epoch parts
+const tz = new Temporal.TimeZone("-00:00:00.000000002");
+const datetime = new Temporal.ZonedDateTime(3661_001_001_001n, tz);
+
+const time = Temporal.PlainTime.from(datetime);
+
+TemporalHelpers.assertPlainTime(time, 1, 1, 1, 1, 0, 999);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-zoneddatetime-negative-epochnanoseconds.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-zoneddatetime-negative-epochnanoseconds.js
new file mode 100644
index 0000000000..158a658a1f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-zoneddatetime-negative-epochnanoseconds.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: A pre-epoch value is handled correctly by the modulo operation in GetISOPartsFromEpoch
+info: |
+    sec-temporal-getisopartsfromepoch step 1:
+      1. Let _remainderNs_ be the mathematical value whose sign is the sign of _epochNanoseconds_ and whose magnitude is abs(_epochNanoseconds_) modulo 10<sup>6</sup>.
+    sec-temporal-builtintimezonegetplaindatetimefor step 2:
+      2. Let _result_ be ! GetISOPartsFromEpoch(_instant_.[[Nanoseconds]]).
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const datetime = new Temporal.ZonedDateTime(-13849764_999_999_999n, "UTC");
+
+// This code path shows up anywhere we convert an exact time, before the Unix
+// epoch, with nonzero microseconds or nanoseconds, into a wall time.
+
+const result = Temporal.PlainTime.from(datetime);
+TemporalHelpers.assertPlainTime(result, 16, 50, 35, 0, 0, 1);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-non-integer.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-non-integer.js
new file mode 100644
index 0000000000..354e99cf54
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-non-integer.js
@@ -0,0 +1,18 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: RangeError thrown if time zone reports an offset that is not an integer number of nanoseconds
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[3600_000_000_000.5, NaN].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  assert.throws(RangeError, () => Temporal.PlainTime.from(datetime));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js
new file mode 100644
index 0000000000..5ee3f89ac8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js
@@ -0,0 +1,21 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-temporal.plaintime.from
+description: TypeError thrown if timeZone.getOffsetNanosecondsFor is not callable
+features: [BigInt, Symbol, Temporal, arrow-function]
+---*/
+
+[undefined, null, true, Math.PI, 'string', Symbol('sym'), 42n, {}].forEach(notCallable => {
+  const timeZone = new Temporal.TimeZone("UTC");
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  timeZone.getOffsetNanosecondsFor = notCallable;
+  assert.throws(
+    TypeError,
+    () => Temporal.PlainTime.from(datetime),
+    `Uncallable ${notCallable === null ? 'null' : typeof notCallable} getOffsetNanosecondsFor should throw TypeError`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-out-of-range.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-out-of-range.js
new file mode 100644
index 0000000000..bd2e640887
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-out-of-range.js
@@ -0,0 +1,18 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: RangeError thrown if time zone reports an offset that is out of range
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[-86400_000_000_001, 86400_000_000_001, -Infinity, Infinity].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  assert.throws(RangeError, () => Temporal.PlainTime.from(datetime));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-wrong-type.js
new file mode 100644
index 0000000000..350fbd57c0
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-wrong-type.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: TypeError thrown if time zone reports an offset that is not a Number
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[
+  undefined,
+  null,
+  true,
+  "+01:00",
+  Symbol(),
+  3600_000_000_000n,
+  {},
+  { valueOf() { return 3600_000_000_000; } },
+].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  assert.throws(TypeError, () => Temporal.PlainTime.from(datetime));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/builtin.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/builtin.js
new file mode 100644
index 0000000000..5748262b20
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/builtin.js
@@ -0,0 +1,33 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: Tests that Temporal.PlainTime.from meets the requirements for built-in objects
+info: |
+    Built-in functions that are not constructors do not have a "prototype" property unless
+    otherwise specified in the description of a particular function.
+
+    Unless specified otherwise, a built-in object that is callable as a function is a built-in
+    function object with the characteristics described in 10.3. Unless specified otherwise, the
+    [[Extensible]] internal slot of a built-in object initially has the value true.
+
+    Unless otherwise specified every built-in function and every built-in constructor has the
+    Function prototype object [...] as the value of its [[Prototype]] internal slot.
+features: [Temporal]
+---*/
+
+assert.sameValue(Object.isExtensible(Temporal.PlainTime.from),
+  true, "Built-in objects must be extensible.");
+
+assert.sameValue(Object.prototype.toString.call(Temporal.PlainTime.from),
+  "[object Function]", "Object.prototype.toString");
+
+assert.sameValue(Object.getPrototypeOf(Temporal.PlainTime.from),
+  Function.prototype, "prototype");
+
+assert.sameValue(Temporal.PlainTime.from.hasOwnProperty("prototype"),
+  false, "prototype property");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/calendar-temporal-object.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/calendar-temporal-object.js
new file mode 100644
index 0000000000..60c93ebc22
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/calendar-temporal-object.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: Fast path for converting other Temporal objects to Temporal.Calendar by reading internal slots
+info: |
+    sec-temporal.plaintime.from step 4:
+      4. Return ? ToTemporalTime(_temporalTime_, _overflow_).
+    sec-temporal-totemporaltime step 3.d:
+      d. If _calendar_ is not *undefined*, then
+        i. Set _calendar_ to ? ToTemporalCalendar(_calendar_).
+        ii. If ? ToString(_calendar_) is not *"iso8601"*, then
+          1. Throw a *RangeError* exception.
+    sec-temporal-totemporalcalendar step 1.a:
+      a. If _temporalCalendarLike_ has an [[InitializedTemporalDate]], [[InitializedTemporalDateTime]], [[InitializedTemporalMonthDay]], [[InitializedTemporalYearMonth]], or [[InitializedTemporalZonedDateTime]] internal slot, then
+        i. Return _temporalCalendarLike_.[[Calendar]].
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+TemporalHelpers.checkToTemporalCalendarFastPath((temporalObject) => {
+  assert.throws(RangeError, () => Temporal.PlainTime.from({ hour: 12, minute: 34, second: 56, calendar: temporalObject }));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/infinity-throws-rangeerror.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/infinity-throws-rangeerror.js
new file mode 100644
index 0000000000..266c3fd7ce
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/infinity-throws-rangeerror.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Throws if any value in the property bag is Infinity or -Infinity
+esid: sec-temporal.plaintime.from
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const base = { hour: 15, minute: 30, second: 45, millisecond: 987, microsecond: 654, nanosecond: 321 };
+
+[Infinity, -Infinity].forEach((inf) => {
+  ["hour", "minute", "second", "millisecond", "microsecond", "nanosecond"].forEach((prop) => {
+    ["constrain", "reject"].forEach((overflow) => {
+      assert.throws(RangeError, () => Temporal.PlainTime.from({ ...base, [prop]: inf }, { overflow }), `${prop} property cannot be ${inf} (overflow ${overflow}`);
+
+      const calls = [];
+      const obj = TemporalHelpers.toPrimitiveObserver(calls, inf, prop);
+      assert.throws(RangeError, () => Temporal.PlainTime.from({ ...base, [prop]: obj }, { overflow }));
+      assert.compareArray(calls, [`get ${prop}.valueOf`, `call ${prop}.valueOf`], "it fails after fetching the primitive value");
+    });
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/leap-second.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/leap-second.js
new file mode 100644
index 0000000000..3155e51d55
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/leap-second.js
@@ -0,0 +1,43 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: Leap second is a valid ISO string for PlainTime
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+let arg = "2016-12-31T23:59:60";
+
+const result1 = Temporal.PlainTime.from(arg);
+TemporalHelpers.assertPlainTime(
+  result1,
+  23, 59, 59, 0, 0, 0,
+  "leap second is a valid ISO string for PlainTime"
+);
+
+const result2 = Temporal.PlainTime.from(arg, { overflow: "reject" });
+TemporalHelpers.assertPlainTime(
+  result2,
+  23, 59, 59, 0, 0, 0,
+  "leap second is a valid ISO string for PlainTime"
+);
+
+arg = { year: 2016, month: 12, day: 31, hour: 23, minute: 59, second: 60 };
+
+const result3 = Temporal.PlainTime.from(arg);
+TemporalHelpers.assertPlainTime(
+  result3,
+  23, 59, 59, 0, 0, 0,
+  "second: 60 is ignored in property bag for PlainTime"
+);
+
+assert.throws(
+  RangeError,
+  () => Temporal.PlainTime.from(arg, { overflow: "reject" }),
+  "second: 60 is rejected in property bag for PlainTime with overflow: reject"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/length.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/length.js
new file mode 100644
index 0000000000..e76663b3ec
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/length.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: Temporal.PlainTime.from.length is 1
+info: |
+    Every built-in function object, including constructors, has a "length" property whose value is
+    an integer. Unless otherwise specified, this value is equal to the largest number of named
+    arguments shown in the subclause headings for the function description. Optional parameters
+    (which are indicated with brackets: [ ]) or rest parameters (which are shown using the form
+    «...name») are not included in the default argument count.
+
+    Unless otherwise specified, the "length" property of a built-in function object has the
+    attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.from, "length", {
+  value: 1,
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/name.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/name.js
new file mode 100644
index 0000000000..7eab2a4535
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/name.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: Temporal.PlainTime.from.name is "from"
+info: |
+    Every built-in function object, including constructors, that is not identified as an anonymous
+    function has a "name" property whose value is a String. Unless otherwise specified, this value
+    is the name that is given to the function in this specification.
+
+    Unless otherwise specified, the "name" property of a built-in function object, if it exists,
+    has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.from, "name", {
+  value: "from",
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/not-a-constructor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/not-a-constructor.js
new file mode 100644
index 0000000000..3f3eb71b6b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/not-a-constructor.js
@@ -0,0 +1,23 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: Temporal.PlainTime.from does not implement [[Construct]], is not new-able
+info: |
+    Built-in function objects that are not identified as constructors do not implement the
+    [[Construct]] internal method unless otherwise specified in the description of a particular
+    function.
+includes: [isConstructor.js]
+features: [Reflect.construct, Temporal]
+---*/
+
+assert.throws(TypeError, () => {
+  new Temporal.PlainTime.from();
+}, "Calling as constructor");
+
+assert.sameValue(isConstructor(Temporal.PlainTime.from), false,
+  "isConstructor(Temporal.PlainTime.from)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/observable-get-overflow-argument-string-invalid.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/observable-get-overflow-argument-string-invalid.js
new file mode 100644
index 0000000000..2bce19d35d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/observable-get-overflow-argument-string-invalid.js
@@ -0,0 +1,29 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: overflow property is extracted with ISO-invalid string argument.
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const expected = [
+  "get overflow",
+  "get overflow.toString",
+  "call overflow.toString",
+];
+
+let actual = [];
+const object = {
+  get overflow() {
+    actual.push("get overflow");
+    return TemporalHelpers.toPrimitiveObserver(actual, "constrain", "overflow");
+  }
+};
+
+assert.throws(RangeError, () => Temporal.PlainTime.from("24:60", object));
+assert.compareArray(actual, expected);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/options-invalid.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/options-invalid.js
new file mode 100644
index 0000000000..d1a9618348
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/options-invalid.js
@@ -0,0 +1,17 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: TypeError thrown when a primitive is passed as the options argument
+features: [Temporal]
+---*/
+
+const values = [null, true, "hello", Symbol("foo"), 1, 1n];
+
+for (const badOptions of values) {
+  assert.throws(TypeError, () => Temporal.PlainTime.from({ hours: 12 }, badOptions));
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/options-object.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/options-object.js
new file mode 100644
index 0000000000..b95f0dae12
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/options-object.js
@@ -0,0 +1,22 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.from
+description: Empty object may be used as options
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+TemporalHelpers.assertPlainTime(
+  Temporal.PlainTime.from({ hour: 12, minute: 34 }, {}), 12, 34, 0, 0, 0, 0,
+  "options may be an empty plain object"
+);
+
+TemporalHelpers.assertPlainTime(
+  Temporal.PlainTime.from({ hour: 12, minute: 34 }, () => {}), 12, 34, 0, 0, 0, 0,
+  "options may be an empty function object"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/options-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/options-undefined.js
new file mode 100644
index 0000000000..cb91de4096
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/options-undefined.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: Verify that undefined options are handled correctly.
+features: [Temporal]
+---*/
+
+const fields = { hour: 12, minute: 60 };
+
+const explicit = Temporal.PlainTime.from(fields, undefined);
+assert.sameValue(explicit.minute, 59, "default overflow is constrain");
+
+const implicit = Temporal.PlainTime.from(fields);
+assert.sameValue(implicit.minute, 59, "default overflow is constrain");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/options-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/options-wrong-type.js
new file mode 100644
index 0000000000..c233755fb5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/options-wrong-type.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: TypeError thrown when options argument is a primitive
+features: [BigInt, Symbol, Temporal]
+---*/
+
+const badOptions = [
+  null,
+  true,
+  "some string",
+  Symbol(),
+  1,
+  2n,
+];
+
+for (const value of badOptions) {
+  assert.throws(TypeError, () => Temporal.PlainTime.from({ hour: 12, minute: 34 }, value),
+    `TypeError on wrong options type ${typeof value}`);
+};
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/order-of-operations.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/order-of-operations.js
new file mode 100644
index 0000000000..0ab7c96999
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/order-of-operations.js
@@ -0,0 +1,58 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: Properties on an object passed to from() are accessed in the correct order
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const expected = [
+  "get options.overflow",
+  "get options.overflow.toString",
+  "call options.overflow.toString",
+  "get fields.calendar",
+  "get fields.calendar.toString",
+  "call fields.calendar.toString",
+  // ToTemporalTimeRecord
+  "get fields.hour",
+  "get fields.hour.valueOf",
+  "call fields.hour.valueOf",
+  "get fields.microsecond",
+  "get fields.microsecond.valueOf",
+  "call fields.microsecond.valueOf",
+  "get fields.millisecond",
+  "get fields.millisecond.valueOf",
+  "call fields.millisecond.valueOf",
+  "get fields.minute",
+  "get fields.minute.valueOf",
+  "call fields.minute.valueOf",
+  "get fields.nanosecond",
+  "get fields.nanosecond.valueOf",
+  "call fields.nanosecond.valueOf",
+  "get fields.second",
+  "get fields.second.valueOf",
+  "call fields.second.valueOf",
+];
+const actual = [];
+
+const fields = TemporalHelpers.propertyBagObserver(actual, {
+  hour: 1.7,
+  minute: 1.7,
+  second: 1.7,
+  millisecond: 1.7,
+  microsecond: 1.7,
+  nanosecond: 1.7,
+  calendar: "iso8601",
+}, "fields");
+
+const options = TemporalHelpers.propertyBagObserver(actual, {
+  overflow: "constrain",
+}, "options");
+
+const result = Temporal.PlainTime.from(fields, options);
+assert.compareArray(actual, expected, "order of operations");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/overflow-constrain.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/overflow-constrain.js
new file mode 100644
index 0000000000..f90f3ab472
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/overflow-constrain.js
@@ -0,0 +1,17 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: constrain value for overflow option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+TemporalHelpers.assertPlainTime(Temporal.PlainTime.from({ hour: 26 }, { overflow: "constrain" }),
+  23, 0, 0, 0, 0, 0);
+TemporalHelpers.assertPlainTime(Temporal.PlainTime.from({ hour: 22 }, { overflow: "constrain" }),
+  22, 0, 0, 0, 0, 0);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/overflow-invalid-string.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/overflow-invalid-string.js
new file mode 100644
index 0000000000..3ea17b312d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/overflow-invalid-string.js
@@ -0,0 +1,35 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: RangeError thrown when overflow option not one of the allowed string values
+info: |
+    sec-getoption step 10:
+      10. If _values_ is not *undefined* and _values_ does not contain an element equal to _value_, throw a *RangeError* exception.
+    sec-temporal-totemporaloverflow step 1:
+      1. Return ? GetOption(_normalizedOptions_, *"overflow"*, « String », « *"constrain"*, *"reject"* », *"constrain"*).
+    sec-temporal.plaintime.from step 2:
+      2. Let _overflow_ be ? ToTemporalOverflow(_options_).
+features: [Temporal]
+---*/
+
+const validValues = [
+  new Temporal.PlainTime(12),
+  { hour: 12 },
+  "12:00",
+];
+
+const badOverflows = ["", "CONSTRAIN", "balance", "other string", "constra\u0131n", "reject\0"];
+for (const value of validValues) {
+  for (const overflow of badOverflows) {
+    assert.throws(
+      RangeError,
+      () => Temporal.PlainTime.from(value, { overflow }),
+      `invalid overflow ("${overflow}")`
+    );
+  }
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/overflow-reject.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/overflow-reject.js
new file mode 100644
index 0000000000..de14a1a548
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/overflow-reject.js
@@ -0,0 +1,16 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: reject value for overflow option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+assert.throws(RangeError, () => Temporal.PlainTime.from({ hour: 26 }, { overflow: "reject" }));
+TemporalHelpers.assertPlainTime(Temporal.PlainTime.from({ hour: 22 }, { overflow: "reject" }),
+  22, 0, 0, 0, 0, 0);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/overflow-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/overflow-undefined.js
new file mode 100644
index 0000000000..8783aaba7e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/overflow-undefined.js
@@ -0,0 +1,40 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: Fallback value for overflow option
+info: |
+    sec-getoption step 3:
+      3. If _value_ is *undefined*, return _fallback_.
+    sec-temporal-totemporaloverflow step 1:
+      1. Return ? GetOption(_normalizedOptions_, *"overflow"*, « String », « *"constrain"*, *"reject"* », *"constrain"*).
+    sec-temporal.plaintime.from step 2:
+      2. Let _overflow_ be ? ToTemporalOverflow(_options_).
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const validValues = [
+  new Temporal.PlainTime(12),
+  "12:00",
+];
+validValues.forEach((value) => {
+  const explicit = Temporal.PlainTime.from(value, { overflow: undefined });
+  TemporalHelpers.assertPlainTime(explicit, 12, 0, 0, 0, 0, 0, "overflow is ignored");
+  const implicit = Temporal.PlainTime.from(value, {});
+  TemporalHelpers.assertPlainTime(implicit, 12, 0, 0, 0, 0, 0, "overflow is ignored");
+  const lambda = Temporal.PlainTime.from(value, () => {});
+  TemporalHelpers.assertPlainTime(lambda, 12, 0, 0, 0, 0, 0, "overflow is ignored");
+});
+
+const propertyBag = { hour: 26 };
+const explicit = Temporal.PlainTime.from(propertyBag, { overflow: undefined });
+TemporalHelpers.assertPlainTime(explicit, 23, 0, 0, 0, 0, 0, "default overflow is constrain");
+const implicit = Temporal.PlainTime.from(propertyBag, {});
+TemporalHelpers.assertPlainTime(implicit, 23, 0, 0, 0, 0, 0, "default overflow is constrain");
+const lambda = Temporal.PlainTime.from(propertyBag, () => {});
+TemporalHelpers.assertPlainTime(lambda, 23, 0, 0, 0, 0, 0, "default overflow is constrain");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/overflow-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/overflow-wrong-type.js
new file mode 100644
index 0000000000..65a751e10e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/overflow-wrong-type.js
@@ -0,0 +1,29 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: Type conversions for overflow option
+info: |
+    sec-getoption step 9.a:
+      a. Set _value_ to ? ToString(_value_).
+    sec-temporal-totemporaloverflow step 1:
+      1. Return ? GetOption(_normalizedOptions_, *"overflow"*, « String », « *"constrain"*, *"reject"* », *"constrain"*).
+    sec-temporal.plaintime.from step 2:
+      2. Let _overflow_ be ? ToTemporalOverflow(_options_).
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const validValues = [
+  new Temporal.PlainTime(12),
+  { hour: 12 },
+  "12:00",
+];
+validValues.forEach((value) => TemporalHelpers.checkStringOptionWrongType("overflow", "constrain",
+  (overflow) => Temporal.PlainTime.from(value, { overflow }),
+  (result, descr) => TemporalHelpers.assertPlainTime(result, 12, 0, 0, 0, 0, 0, descr),
+));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/plaintime-propertybag-no-time-units.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/plaintime-propertybag-no-time-units.js
new file mode 100644
index 0000000000..d0dcd88db8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/plaintime-propertybag-no-time-units.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: Missing time units in property bag default to 0
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const props = {};
+assert.throws(TypeError, () => Temporal.PlainTime.from(props), "TypeError if at least one property is not present");
+
+props.minute = 30;
+const result = Temporal.PlainTime.from(props);
+TemporalHelpers.assertPlainTime(result, 0, 30, 0, 0, 0, 0, "missing time units default to 0");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/prop-desc.js
new file mode 100644
index 0000000000..fce91759d7
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/prop-desc.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: The "from" property of Temporal.PlainTime
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+assert.sameValue(
+  typeof Temporal.PlainTime.from,
+  "function",
+  "`typeof PlainTime.from` is `function`"
+);
+
+verifyProperty(Temporal.PlainTime, "from", {
+  writable: true,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/subclassing-ignored.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/subclassing-ignored.js
new file mode 100644
index 0000000000..6911f533d3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/subclassing-ignored.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: The receiver is never called when calling from()
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+TemporalHelpers.checkSubclassingIgnoredStatic(
+  Temporal.PlainTime,
+  "from",
+  ["12:34:56.987654321"],
+  (result) => TemporalHelpers.assertPlainTime(result, 12, 34, 56, 987, 654, 321),
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/from/year-zero.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/year-zero.js
new file mode 100644
index 0000000000..d13a40facd
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/from/year-zero.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.from
+description: Negative zero, as an extended year, is rejected
+features: [Temporal, arrow-function]
+---*/
+
+const invalidStrings = [
+  "-000000-12-07T03:24:30",
+  "-000000-12-07T03:24:30+01:00",
+  "-000000-12-07T03:24:30+00:00[UTC]",
+];
+
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainTime.from(arg),
+    "reject minus zero as extended year"
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/hour-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/hour-undefined.js
new file mode 100644
index 0000000000..60c5537943
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/hour-undefined.js
@@ -0,0 +1,18 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime
+description: Hour argument defaults to 0 if not given
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const explicit = new Temporal.PlainTime(undefined);
+TemporalHelpers.assertPlainTime(explicit, 0, 0, 0, 0, 0, 0, "explicit");
+
+const implicit = new Temporal.PlainTime();
+TemporalHelpers.assertPlainTime(implicit, 0, 0, 0, 0, 0, 0, "implicit");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/infinity-throws-rangeerror.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/infinity-throws-rangeerror.js
new file mode 100644
index 0000000000..6d73ab55c1
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/infinity-throws-rangeerror.js
@@ -0,0 +1,60 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Temporal.PlainTime throws a RangeError if any value is Infinity
+esid: sec-temporal.plaintime
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+assert.throws(RangeError, () => new Temporal.PlainTime(Infinity));
+assert.throws(RangeError, () => new Temporal.PlainTime(0, Infinity));
+assert.throws(RangeError, () => new Temporal.PlainTime(0, 0, Infinity));
+assert.throws(RangeError, () => new Temporal.PlainTime(0, 0, 0, Infinity));
+assert.throws(RangeError, () => new Temporal.PlainTime(0, 0, 0, 0, Infinity));
+assert.throws(RangeError, () => new Temporal.PlainTime(0, 0, 0, 0, 0, Infinity));
+
+const O = (primitiveValue, propertyName) => (calls) => TemporalHelpers.toPrimitiveObserver(calls, primitiveValue, propertyName);
+const tests = [
+  [
+    "infinite hour",
+    [O(Infinity, "hour"), O(1, "minute"), O(1, "second"), O(1, "millisecond"), O(1, "microsecond"), O(1, "nanosecond")],
+    ["get hour.valueOf", "call hour.valueOf"]
+  ],
+  [
+    "infinite minute",
+    [O(1, "hour"), O(Infinity, "minute"), O(1, "second"), O(1, "millisecond"), O(1, "microsecond"), O(1, "nanosecond")],
+    ["get hour.valueOf", "call hour.valueOf", "get minute.valueOf", "call minute.valueOf"]
+  ],
+  [
+    "infinite second",
+    [O(1, "hour"), O(1, "minute"), O(Infinity, "second"), O(1, "millisecond"), O(1, "microsecond"), O(1, "nanosecond")],
+    ["get hour.valueOf", "call hour.valueOf", "get minute.valueOf", "call minute.valueOf", "get second.valueOf", "call second.valueOf"]
+  ],
+  [
+    "infinite millisecond",
+    [O(1, "hour"), O(1, "minute"), O(1, "second"), O(Infinity, "millisecond"), O(1, "microsecond"), O(1, "nanosecond")],
+    ["get hour.valueOf", "call hour.valueOf", "get minute.valueOf", "call minute.valueOf", "get second.valueOf", "call second.valueOf", "get millisecond.valueOf", "call millisecond.valueOf"]
+  ],
+  [
+    "infinite microsecond",
+    [O(1, "hour"), O(1, "minute"), O(1, "second"), O(1, "millisecond"), O(Infinity, "microsecond"), O(1, "nanosecond")],
+    ["get hour.valueOf", "call hour.valueOf", "get minute.valueOf", "call minute.valueOf", "get second.valueOf", "call second.valueOf", "get millisecond.valueOf", "call millisecond.valueOf", "get microsecond.valueOf", "call microsecond.valueOf"]
+  ],
+  [
+    "infinite nanosecond",
+    [O(1, "hour"), O(1, "minute"), O(1, "second"), O(1, "millisecond"), O(1, "microsecond"), O(Infinity, "nanosecond")],
+    ["get hour.valueOf", "call hour.valueOf", "get minute.valueOf", "call minute.valueOf", "get second.valueOf", "call second.valueOf", "get millisecond.valueOf", "call millisecond.valueOf", "get microsecond.valueOf", "call microsecond.valueOf", "get nanosecond.valueOf", "call nanosecond.valueOf"]
+  ],
+];
+
+for (const [description, args, expected] of tests) {
+  const actual = [];
+  const args_ = args.map((o) => o(actual));
+  assert.throws(RangeError, () => new Temporal.PlainTime(...args_), description);
+  assert.compareArray(actual, expected, `${description} order of operations`);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/length.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/length.js
new file mode 100644
index 0000000000..f295b90025
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/length.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime
+description: Temporal.PlainTime.length is 0
+info: |
+    Every built-in function object, including constructors, has a "length" property whose value is
+    an integer. Unless otherwise specified, this value is equal to the largest number of named
+    arguments shown in the subclause headings for the function description. Optional parameters
+    (which are indicated with brackets: [ ]) or rest parameters (which are shown using the form
+    «...name») are not included in the default argument count.
+
+    Unless otherwise specified, the "length" property of a built-in function object has the
+    attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime, "length", {
+  value: 0,
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/microsecond-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/microsecond-undefined.js
new file mode 100644
index 0000000000..d0bc70ec8a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/microsecond-undefined.js
@@ -0,0 +1,20 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime
+description: Microsecond argument defaults to 0 if not given
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const args = [12, 34, 56, 123];
+
+const explicit = new Temporal.PlainTime(...args, undefined);
+TemporalHelpers.assertPlainTime(explicit, ...args, 0, 0, "explicit");
+
+const implicit = new Temporal.PlainTime(...args);
+TemporalHelpers.assertPlainTime(implicit, ...args, 0, 0, "implicit");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/millisecond-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/millisecond-undefined.js
new file mode 100644
index 0000000000..7b7dc0e52b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/millisecond-undefined.js
@@ -0,0 +1,20 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime
+description: Millisecond argument defaults to 0 if not given
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const args = [12, 34, 56];
+
+const explicit = new Temporal.PlainTime(...args, undefined);
+TemporalHelpers.assertPlainTime(explicit, ...args, 0, 0, 0, "explicit");
+
+const implicit = new Temporal.PlainTime(...args);
+TemporalHelpers.assertPlainTime(implicit, ...args, 0, 0, 0, "implicit");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/minute-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/minute-undefined.js
new file mode 100644
index 0000000000..d429e952c0
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/minute-undefined.js
@@ -0,0 +1,20 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime
+description: Minute argument defaults to 0 if not given
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const hour = 12;
+
+const explicit = new Temporal.PlainTime(hour, undefined);
+TemporalHelpers.assertPlainTime(explicit, hour, 0, 0, 0, 0, 0, "explicit");
+
+const implicit = new Temporal.PlainTime(hour);
+TemporalHelpers.assertPlainTime(implicit, hour, 0, 0, 0, 0, 0, "implicit");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/name.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/name.js
new file mode 100644
index 0000000000..5db577b359
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/name.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime
+description: Temporal.PlainTime.name is "PlainTime"
+info: |
+    Every built-in function object, including constructors, that is not identified as an anonymous
+    function has a "name" property whose value is a String. Unless otherwise specified, this value
+    is the name that is given to the function in this specification.
+
+    Unless otherwise specified, the "name" property of a built-in function object, if it exists,
+    has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime, "name", {
+  value: "PlainTime",
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/nanosecond-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/nanosecond-undefined.js
new file mode 100644
index 0000000000..b1d21cabaa
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/nanosecond-undefined.js
@@ -0,0 +1,20 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime
+description: Nanosecond argument defaults to 0 if not given
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const args = [12, 34, 56, 123, 456];
+
+const explicit = new Temporal.PlainTime(...args, undefined);
+TemporalHelpers.assertPlainTime(explicit, ...args, 0, "explicit");
+
+const implicit = new Temporal.PlainTime(...args);
+TemporalHelpers.assertPlainTime(implicit, ...args, 0, "implicit");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/negative-infinity-throws-rangeerror.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/negative-infinity-throws-rangeerror.js
new file mode 100644
index 0000000000..6c3efde1af
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/negative-infinity-throws-rangeerror.js
@@ -0,0 +1,60 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Temporal.PlainDate throws a RangeError if any value is -Infinity
+esid: sec-temporal.plaintime
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+assert.throws(RangeError, () => new Temporal.PlainTime(-Infinity));
+assert.throws(RangeError, () => new Temporal.PlainTime(0, -Infinity));
+assert.throws(RangeError, () => new Temporal.PlainTime(0, 0, -Infinity));
+assert.throws(RangeError, () => new Temporal.PlainTime(0, 0, 0, -Infinity));
+assert.throws(RangeError, () => new Temporal.PlainTime(0, 0, 0, 0, -Infinity));
+assert.throws(RangeError, () => new Temporal.PlainTime(0, 0, 0, 0, 0, -Infinity));
+
+const O = (primitiveValue, propertyName) => (calls) => TemporalHelpers.toPrimitiveObserver(calls, primitiveValue, propertyName);
+const tests = [
+  [
+    "infinite hour",
+    [O(-Infinity, "hour"), O(1, "minute"), O(1, "second"), O(1, "millisecond"), O(1, "microsecond"), O(1, "nanosecond")],
+    ["get hour.valueOf", "call hour.valueOf"]
+  ],
+  [
+    "infinite minute",
+    [O(1, "hour"), O(-Infinity, "minute"), O(1, "second"), O(1, "millisecond"), O(1, "microsecond"), O(1, "nanosecond")],
+    ["get hour.valueOf", "call hour.valueOf", "get minute.valueOf", "call minute.valueOf"]
+  ],
+  [
+    "infinite second",
+    [O(1, "hour"), O(1, "minute"), O(-Infinity, "second"), O(1, "millisecond"), O(1, "microsecond"), O(1, "nanosecond")],
+    ["get hour.valueOf", "call hour.valueOf", "get minute.valueOf", "call minute.valueOf", "get second.valueOf", "call second.valueOf"]
+  ],
+  [
+    "infinite millisecond",
+    [O(1, "hour"), O(1, "minute"), O(1, "second"), O(-Infinity, "millisecond"), O(1, "microsecond"), O(1, "nanosecond")],
+    ["get hour.valueOf", "call hour.valueOf", "get minute.valueOf", "call minute.valueOf", "get second.valueOf", "call second.valueOf", "get millisecond.valueOf", "call millisecond.valueOf"]
+  ],
+  [
+    "infinite microsecond",
+    [O(1, "hour"), O(1, "minute"), O(1, "second"), O(1, "millisecond"), O(-Infinity, "microsecond"), O(1, "nanosecond")],
+    ["get hour.valueOf", "call hour.valueOf", "get minute.valueOf", "call minute.valueOf", "get second.valueOf", "call second.valueOf", "get millisecond.valueOf", "call millisecond.valueOf", "get microsecond.valueOf", "call microsecond.valueOf"]
+  ],
+  [
+    "infinite nanosecond",
+    [O(1, "hour"), O(1, "minute"), O(1, "second"), O(1, "millisecond"), O(1, "microsecond"), O(-Infinity, "nanosecond")],
+    ["get hour.valueOf", "call hour.valueOf", "get minute.valueOf", "call minute.valueOf", "get second.valueOf", "call second.valueOf", "get millisecond.valueOf", "call millisecond.valueOf", "get microsecond.valueOf", "call microsecond.valueOf", "get nanosecond.valueOf", "call nanosecond.valueOf"]
+  ],
+];
+
+for (const [description, args, expected] of tests) {
+  const actual = [];
+  const args_ = args.map((o) => o(actual));
+  assert.throws(RangeError, () => new Temporal.PlainTime(...args_), description);
+  assert.compareArray(actual, expected, `${description} order of operations`);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/negative-zero.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/negative-zero.js
new file mode 100644
index 0000000000..ead1776bcd
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/negative-zero.js
@@ -0,0 +1,15 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime
+description: Negative zero arguments are treated as zero.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const plainTime = new Temporal.PlainTime(-0, -0, -0, -0, -0, -0);
+TemporalHelpers.assertPlainTime(plainTime, 0, 0, 0, 0, 0, 0);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prop-desc.js
new file mode 100644
index 0000000000..22139579e5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prop-desc.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime
+description: The "PlainTime" property of Temporal
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+assert.sameValue(
+  typeof Temporal.PlainTime,
+  "function",
+  "`typeof PlainTime` is `function`"
+);
+
+verifyProperty(Temporal, "PlainTime", {
+  writable: true,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-duration.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-duration.js
new file mode 100644
index 0000000000..c7d899ee22
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-duration.js
@@ -0,0 +1,17 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: Duration arguments are supported.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const plainTime = new Temporal.PlainTime(15, 23, 30, 123, 456, 789);
+const duration = Temporal.Duration.from("PT16H");
+TemporalHelpers.assertPlainTime(plainTime.add(duration),
+  7, 23, 30, 123, 456, 789);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-higher-units.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-higher-units.js
new file mode 100644
index 0000000000..2d1bb31cb1
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-higher-units.js
@@ -0,0 +1,32 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: Higher units are ignored.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const plainTime = new Temporal.PlainTime(15, 23, 30, 123, 456, 789);
+const values = [
+  new Temporal.Duration(0, 0, 0, 1),
+  new Temporal.Duration(0, 0, 1),
+  new Temporal.Duration(0, 1),
+  new Temporal.Duration(1),
+  { days: 1 },
+  { weeks: 1 },
+  { months: 1 },
+  { years: 1 },
+  "P1D",
+  "P1W",
+  "P1M",
+  "P1Y",
+];
+for (const value of values) {
+  TemporalHelpers.assertPlainTime(plainTime.add(value),
+    15, 23, 30, 123, 456, 789);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-invalid-property.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-invalid-property.js
new file mode 100644
index 0000000000..62d2cf2e84
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-invalid-property.js
@@ -0,0 +1,31 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: temporalDurationLike object must contain at least one correctly spelled property
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(15, 30, 45, 987, 654, 321);
+
+assert.throws(
+  TypeError,
+  () => instance.add({}),
+  "Throws TypeError if no property is present"
+);
+
+assert.throws(
+  TypeError,
+  () => instance.add({ nonsense: true }),
+  "Throws TypeError if no recognized property is present"
+);
+
+assert.throws(
+  TypeError,
+  () => instance.add({ sign: 1 }),
+  "Sign property is not recognized"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-mixed-sign.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-mixed-sign.js
new file mode 100644
index 0000000000..3bc20511cb
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-mixed-sign.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: Positive and negative values in the temporalDurationLike argument are not acceptable
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(15, 30, 45, 987, 654, 321);
+
+assert.throws(
+  RangeError,
+  () => instance.add({ hours: 1, minutes: -30 }),
+  `mixed positive and negative values always throw`
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-not-object.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-not-object.js
new file mode 100644
index 0000000000..020ccbb6d7
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-not-object.js
@@ -0,0 +1,22 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: Passing a primitive other than string to add() throws
+features: [Symbol, Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(15, 30, 45, 987, 654, 321);
+assert.throws(RangeError, () => instance.add(undefined), "undefined");
+assert.throws(RangeError, () => instance.add(null), "null");
+assert.throws(RangeError, () => instance.add(true), "boolean");
+assert.throws(RangeError, () => instance.add(""), "empty string");
+assert.throws(TypeError, () => instance.add(Symbol()), "Symbol");
+assert.throws(RangeError, () => instance.add(7), "number");
+assert.throws(RangeError, () => instance.add(7n), "bigint");
+assert.throws(TypeError, () => instance.add([]), "array");
+assert.throws(TypeError, () => instance.add(() => {}), "function");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-object.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-object.js
new file mode 100644
index 0000000000..873e365f50
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-object.js
@@ -0,0 +1,40 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: Plain object arguments are supported.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const plainTime = new Temporal.PlainTime(15, 23, 30, 123, 456, 789);
+TemporalHelpers.assertPlainTime(plainTime.add({ hours: 16 }),
+  7, 23, 30, 123, 456, 789, "add 16 hours across midnight boundary");
+TemporalHelpers.assertPlainTime(plainTime.add({ minutes: 45 }),
+  16, 8, 30, 123, 456, 789, "add 45 minutes");
+TemporalHelpers.assertPlainTime(plainTime.add({ seconds: 800 }),
+  15, 36, 50, 123, 456, 789, "add 800 seconds");
+TemporalHelpers.assertPlainTime(plainTime.add({ milliseconds: 800 }),
+  15, 23, 30, 923, 456, 789, "add 800 milliseconds");
+TemporalHelpers.assertPlainTime(plainTime.add({ microseconds: 800 }),
+  15, 23, 30, 124, 256, 789, "add 800 microseconds");
+TemporalHelpers.assertPlainTime(plainTime.add({ nanoseconds: 300 }),
+  15, 23, 30, 123, 457, 89, "add 300 nanoseconds");
+TemporalHelpers.assertPlainTime(Temporal.PlainTime.from("07:23:30.123456789").add({ hours: -16 }),
+  15, 23, 30, 123, 456, 789, "add -16 hours across midnight boundary");
+TemporalHelpers.assertPlainTime(Temporal.PlainTime.from("16:08:30.123456789").add({ minutes: -45 }),
+  15, 23, 30, 123, 456, 789, "add -45 minutes");
+TemporalHelpers.assertPlainTime(Temporal.PlainTime.from("15:36:50.123456789").add({ seconds: -800 }),
+  15, 23, 30, 123, 456, 789, "add -800 seconds");
+TemporalHelpers.assertPlainTime(Temporal.PlainTime.from("15:23:30.923456789").add({ milliseconds: -800 }),
+  15, 23, 30, 123, 456, 789, "add -800 milliseconds");
+TemporalHelpers.assertPlainTime(Temporal.PlainTime.from("15:23:30.124256789").add({ microseconds: -800 }),
+  15, 23, 30, 123, 456, 789, "add -800 microseconds");
+TemporalHelpers.assertPlainTime(Temporal.PlainTime.from("15:23:30.123457089").add({ nanoseconds: -300 }),
+  15, 23, 30, 123, 456, 789, "add -300 nanoseconds");
+TemporalHelpers.assertPlainTime(plainTime.add({ minute: 1, hours: 1 }),
+  16, 23, 30, 123, 456, 789, "misspelled property is ignored");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-singular-properties.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-singular-properties.js
new file mode 100644
index 0000000000..10eefd9a1e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-singular-properties.js
@@ -0,0 +1,30 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: Singular properties in the property bag are always ignored
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(15, 30, 45, 987, 654, 321);
+
+[
+  { year: 1 },
+  { month: 2 },
+  { week: 3 },
+  { day: 4 },
+  { hour: 5 },
+  { minute: 6 },
+  { second: 7 },
+  { millisecond: 8 },
+  { microsecond: 9 },
+  { nanosecond: 10 },
+].forEach((badObject) => {
+  assert.throws(TypeError, () => instance.add(badObject),
+    "Throw TypeError if temporalDurationLike is not valid");
+});
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-string-duration-too-large.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-string-duration-too-large.js
new file mode 100644
index 0000000000..256ecc433a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-string-duration-too-large.js
@@ -0,0 +1,21 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: >
+  ParseTemporalDurationString throws a RangeError when the result is too large.
+features: [Temporal]
+---*/
+
+// Number string too long to be representable as a Number value.
+var ones = "1".repeat(1000);
+assert.sameValue(Number(ones), Infinity);
+
+var time = new Temporal.PlainTime();
+var str = "PT" + ones + "S";
+
+assert.throws(RangeError, () => time.add(str));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-string-fractional-units-rounding-mode.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-string-fractional-units-rounding-mode.js
new file mode 100644
index 0000000000..215481fe2f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-string-fractional-units-rounding-mode.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: Strings with fractional duration units are rounded with the correct rounding mode
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const midnight = new Temporal.PlainTime();
+
+TemporalHelpers.assertPlainTime(midnight.add("PT1.03125H"), 1, 1, 52, 500, 0, 0,
+  "positive fractional units rounded with correct rounding mode");
+TemporalHelpers.assertPlainTime(midnight.add("-PT1.03125H"), 22, 58, 7, 500, 0, 0,
+  "negative fractional units rounded with correct rounding mode");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-string-negative-fractional-units.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-string-negative-fractional-units.js
new file mode 100644
index 0000000000..8230d6119a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-string-negative-fractional-units.js
@@ -0,0 +1,20 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: Strings with fractional duration units are treated with the correct sign
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime();
+
+const resultHours = instance.add("-PT24.567890123H");
+TemporalHelpers.assertPlainTime(resultHours, 23, 25, 55, 595, 557, 200, "negative fractional hours");
+
+const resultMinutes = instance.add("-PT1440.567890123M");
+TemporalHelpers.assertPlainTime(resultMinutes, 23, 59, 25, 926, 592, 620, "negative fractional minutes");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-string.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-string.js
new file mode 100644
index 0000000000..fe63233cd2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/argument-string.js
@@ -0,0 +1,16 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: A string is parsed into the correct object when passed as the argument
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = Temporal.PlainTime.from({ hour: 12, minute: 34, second: 56, millisecond: 987, microsecond: 654, nanosecond: 321 });
+const result = instance.add("PT3M");
+TemporalHelpers.assertPlainTime(result, 12, 37, 56, 987, 654, 321);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/balance-negative-time-units.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/balance-negative-time-units.js
new file mode 100644
index 0000000000..0d0d2f58a2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/balance-negative-time-units.js
@@ -0,0 +1,50 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: Negative time fields are balanced upwards
+info: |
+    sec-temporal-balancetime steps 3–14:
+      3. Set _microsecond_ to _microsecond_ + floor(_nanosecond_ / 1000).
+      4. Set _nanosecond_ to _nanosecond_ modulo 1000.
+      5. Set _millisecond_ to _millisecond_ + floor(_microsecond_ / 1000).
+      6. Set _microsecond_ to _microsecond_ modulo 1000.
+      7. Set _second_ to _second_ + floor(_millisecond_ / 1000).
+      8. Set _millisecond_ to _millisecond_ modulo 1000.
+      9. Set _minute_ to _minute_ + floor(_second_ / 60).
+      10. Set _second_ to _second_ modulo 60.
+      11. Set _hour_ to _hour_ + floor(_minute_ / 60).
+      12. Set _minute_ to _minute_ modulo 60.
+      13. Let _days_ be floor(_hour_ / 24).
+      14. Set _hour_ to _hour_ modulo 24.
+    sec-temporal-addtime step 8:
+      8. Return ? BalanceTime(_hour_, _minute_, _second_, _millisecond_, _microsecond_, _nanosecond_).
+    sec-temporal.plaintime.prototype.add step 4:
+      4. Let _result_ be ? AddTime(_temporalTime_.[[ISOHour]], _temporalTime_.[[ISOMinute]], _temporalTime_.[[ISOSecond]], _temporalTime_.[[ISOMillisecond]], _temporalTime_.[[ISOMicrosecond]], _temporalTime_.[[ISONanosecond]], _duration_.[[Hours]], _duration_.[[Minutes]], _duration_.[[Seconds]], _duration_.[[Milliseconds]], _duration_.[[Microseconds]], _duration_.[[Nanoseconds]]).
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(1, 1, 1, 1, 1, 1);
+
+const result1 = time.add(new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 0, -2));
+TemporalHelpers.assertPlainTime(result1, 1, 1, 1, 1, 0, 999, "nanoseconds balance");
+
+const result2 = time.add(new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, -2));
+TemporalHelpers.assertPlainTime(result2, 1, 1, 1, 0, 999, 1, "microseconds balance");
+
+const result3 = time.add(new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, -2));
+TemporalHelpers.assertPlainTime(result3, 1, 1, 0, 999, 1, 1, "milliseconds balance");
+
+const result4 = time.add(new Temporal.Duration(0, 0, 0, 0, 0, 0, -2));
+TemporalHelpers.assertPlainTime(result4, 1, 0, 59, 1, 1, 1, "seconds balance");
+
+const result5 = time.add(new Temporal.Duration(0, 0, 0, 0, 0, -2));
+TemporalHelpers.assertPlainTime(result5, 0, 59, 1, 1, 1, 1, "minutes balance");
+
+const result6 = time.add(new Temporal.Duration(0, 0, 0, 0, -2));
+TemporalHelpers.assertPlainTime(result6, 23, 1, 1, 1, 1, 1, "hours mod 24");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/branding.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/branding.js
new file mode 100644
index 0000000000..68f1755145
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/branding.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: Throw a TypeError if the receiver is invalid
+features: [Symbol, Temporal]
+---*/
+
+const add = Temporal.PlainTime.prototype.add;
+
+assert.sameValue(typeof add, "function");
+
+const args = [new Temporal.Duration(0, 0, 0, 0, 5)];
+
+assert.throws(TypeError, () => add.apply(undefined, args), "undefined");
+assert.throws(TypeError, () => add.apply(null, args), "null");
+assert.throws(TypeError, () => add.apply(true, args), "true");
+assert.throws(TypeError, () => add.apply("", args), "empty string");
+assert.throws(TypeError, () => add.apply(Symbol(), args), "symbol");
+assert.throws(TypeError, () => add.apply(1, args), "1");
+assert.throws(TypeError, () => add.apply({}, args), "plain object");
+assert.throws(TypeError, () => add.apply(Temporal.PlainTime, args), "Temporal.PlainTime");
+assert.throws(TypeError, () => add.apply(Temporal.PlainTime.prototype, args), "Temporal.PlainTime.prototype");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/builtin.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/builtin.js
new file mode 100644
index 0000000000..c64eaf8ea5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/builtin.js
@@ -0,0 +1,36 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: >
+    Tests that Temporal.PlainTime.prototype.add
+    meets the requirements for built-in objects defined by the
+    introduction of chapter 17 of the ECMAScript Language Specification.
+info: |
+    Built-in functions that are not constructors do not have a "prototype" property unless
+    otherwise specified in the description of a particular function.
+
+    Unless specified otherwise, a built-in object that is callable as a function is a built-in
+    function object with the characteristics described in 10.3. Unless specified otherwise, the
+    [[Extensible]] internal slot of a built-in object initially has the value true.
+
+    Unless otherwise specified every built-in function and every built-in constructor has the
+    Function prototype object [...] as the value of its [[Prototype]] internal slot.
+features: [Temporal]
+---*/
+
+assert.sameValue(Object.isExtensible(Temporal.PlainTime.prototype.add),
+  true, "Built-in objects must be extensible.");
+
+assert.sameValue(Object.prototype.toString.call(Temporal.PlainTime.prototype.add),
+  "[object Function]", "Object.prototype.toString");
+
+assert.sameValue(Object.getPrototypeOf(Temporal.PlainTime.prototype.add),
+  Function.prototype, "prototype");
+
+assert.sameValue(Temporal.PlainTime.prototype.add.hasOwnProperty("prototype"),
+  false, "prototype property");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/infinity-throws-rangeerror.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/infinity-throws-rangeerror.js
new file mode 100644
index 0000000000..acc9637662
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/infinity-throws-rangeerror.js
@@ -0,0 +1,38 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Temporal.PlainTime.prototype.add throws a RangeError if any value in a property bag is Infinity
+esid: sec-temporal.plaintime.prototype.add
+features: [Temporal]
+---*/
+
+const overflows = ["constrain", "reject"];
+const fields = ["years", "months", "weeks", "days", "hours", "minutes", "seconds", "milliseconds", "microseconds", "nanoseconds"];
+
+const instance = Temporal.PlainTime.from({ hour: 12, minute: 34, second: 56, millisecond: 987, microsecond: 654, nanosecond: 321 });
+
+overflows.forEach((overflow) => {
+  fields.forEach((field) => {
+    assert.throws(RangeError, () => instance.add({ [field]: Infinity }, { overflow }));
+  });
+});
+
+let calls = 0;
+const obj = {
+  valueOf() {
+    calls++;
+    return Infinity;
+  }
+};
+
+overflows.forEach((overflow) => {
+  fields.forEach((field) => {
+    calls = 0;
+    assert.throws(RangeError, () => instance.add({ [field]: obj }, { overflow }));
+    assert.sameValue(calls, 1, "it fails after fetching the primitive value");
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/length.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/length.js
new file mode 100644
index 0000000000..a5081e08c5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/length.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: Temporal.PlainTime.prototype.add.length is 1
+info: |
+    Every built-in function object, including constructors, has a "length" property whose value is
+    an integer. Unless otherwise specified, this value is equal to the largest number of named
+    arguments shown in the subclause headings for the function description. Optional parameters
+    (which are indicated with brackets: [ ]) or rest parameters (which are shown using the form
+    «...name») are not included in the default argument count.
+
+    Unless otherwise specified, the "length" property of a built-in function object has the
+    attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.add, "length", {
+  value: 1,
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/name.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/name.js
new file mode 100644
index 0000000000..f0774dbe61
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/name.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: Temporal.PlainTime.prototype.add.name is "add".
+info: |
+    Every built-in function object, including constructors, that is not identified as an anonymous
+    function has a "name" property whose value is a String. Unless otherwise specified, this value
+    is the name that is given to the function in this specification.
+
+    Unless otherwise specified, the "name" property of a built-in function object, if it exists,
+    has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.add, "name", {
+  value: "add",
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/negative-infinity-throws-rangeerror.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/negative-infinity-throws-rangeerror.js
new file mode 100644
index 0000000000..981c026dbe
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/negative-infinity-throws-rangeerror.js
@@ -0,0 +1,38 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Temporal.PlainTime.prototype.add throws a RangeError if any value in a property bag is -Infinity
+esid: sec-temporal.plaintime.prototype.add
+features: [Temporal]
+---*/
+
+const overflows = ["constrain", "reject"];
+const fields = ["years", "months", "weeks", "days", "hours", "minutes", "seconds", "milliseconds", "microseconds", "nanoseconds"];
+
+const instance = Temporal.PlainTime.from({ hour: 12, minute: 34, second: 56, millisecond: 987, microsecond: 654, nanosecond: 321 });
+
+overflows.forEach((overflow) => {
+  fields.forEach((field) => {
+    assert.throws(RangeError, () => instance.add({ [field]: -Infinity }, { overflow }));
+  });
+});
+
+let calls = 0;
+const obj = {
+  valueOf() {
+    calls++;
+    return -Infinity;
+  }
+};
+
+overflows.forEach((overflow) => {
+  fields.forEach((field) => {
+    calls = 0;
+    assert.throws(RangeError, () => instance.add({ [field]: obj }, { overflow }));
+    assert.sameValue(calls, 1, "it fails after fetching the primitive value");
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/non-integer-throws-rangeerror.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/non-integer-throws-rangeerror.js
new file mode 100644
index 0000000000..e256ce95d6
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/non-integer-throws-rangeerror.js
@@ -0,0 +1,29 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: A non-integer value for any recognized property in the property bag, throws a RangeError
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(15, 30, 45, 987, 654, 321);
+const fields = [
+  "years",
+  "months",
+  "weeks",
+  "days",
+  "hours",
+  "minutes",
+  "seconds",
+  "milliseconds",
+  "microseconds",
+  "nanoseconds",
+];
+fields.forEach((field) => {
+  assert.throws(RangeError, () => instance.add({ [field]: 1.5 }));
+  assert.throws(RangeError, () => instance.add({ [field]: -1.5 }));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/not-a-constructor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/not-a-constructor.js
new file mode 100644
index 0000000000..41a2780463
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/not-a-constructor.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: >
+  Temporal.PlainTime.prototype.add does not implement [[Construct]], is not new-able
+info: |
+    Built-in function objects that are not identified as constructors do not implement the
+    [[Construct]] internal method unless otherwise specified in the description of a particular
+    function.
+includes: [isConstructor.js]
+features: [Reflect.construct, Temporal]
+---*/
+
+assert.throws(TypeError, () => {
+  new Temporal.PlainTime.prototype.add();
+}, "Calling as constructor");
+
+assert.sameValue(isConstructor(Temporal.PlainTime.prototype.add), false,
+  "isConstructor(Temporal.PlainTime.prototype.add)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/options-ignored.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/options-ignored.js
new file mode 100644
index 0000000000..44bf7959f5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/options-ignored.js
@@ -0,0 +1,32 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: Options argument is ignored.
+includes: [temporalHelpers.js]
+features: [Symbol, Temporal]
+---*/
+
+const values = [
+  undefined,
+  null,
+  true,
+  "hello",
+  Symbol("foo"),
+  1,
+  1n,
+  {},
+  () => {},
+  { get overflow() { throw new Test262Error("should not get overflow") } },
+];
+
+const time = Temporal.PlainTime.from("15:23:30.123456789");
+for (const options of values) {
+  TemporalHelpers.assertPlainTime(time.add({ hours: 1 }, options),
+    16, 23, 30, 123, 456, 789);
+}
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/order-of-operations.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/order-of-operations.js
new file mode 100644
index 0000000000..24e9e75af0
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/order-of-operations.js
@@ -0,0 +1,63 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: Properties on an object passed to add() are accessed in the correct order
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+const expected = [
+  "get fields.days",
+  "get fields.days.valueOf",
+  "call fields.days.valueOf",
+  "get fields.hours",
+  "get fields.hours.valueOf",
+  "call fields.hours.valueOf",
+  "get fields.microseconds",
+  "get fields.microseconds.valueOf",
+  "call fields.microseconds.valueOf",
+  "get fields.milliseconds",
+  "get fields.milliseconds.valueOf",
+  "call fields.milliseconds.valueOf",
+  "get fields.minutes",
+  "get fields.minutes.valueOf",
+  "call fields.minutes.valueOf",
+  "get fields.months",
+  "get fields.months.valueOf",
+  "call fields.months.valueOf",
+  "get fields.nanoseconds",
+  "get fields.nanoseconds.valueOf",
+  "call fields.nanoseconds.valueOf",
+  "get fields.seconds",
+  "get fields.seconds.valueOf",
+  "call fields.seconds.valueOf",
+  "get fields.weeks",
+  "get fields.weeks.valueOf",
+  "call fields.weeks.valueOf",
+  "get fields.years",
+  "get fields.years.valueOf",
+  "call fields.years.valueOf",
+];
+const actual = [];
+const fields = TemporalHelpers.propertyBagObserver(actual, {
+  years: 1,
+  months: 1,
+  weeks: 1,
+  days: 1,
+  hours: 1,
+  minutes: 1,
+  seconds: 1,
+  milliseconds: 1,
+  microseconds: 1,
+  nanoseconds: 1,
+}, "fields");
+const result = instance.add(fields);
+TemporalHelpers.assertPlainTime(result, 13, 35, 57, 988, 655, 322);
+assert.sameValue(result.calendar.id, "iso8601", "calendar result");
+assert.compareArray(actual, expected, "order of operations");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/precision-exact-mathematical-values-1.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/precision-exact-mathematical-values-1.js
new file mode 100644
index 0000000000..a7f8ad2975
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/precision-exact-mathematical-values-1.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: >
+  Duration components are precise mathematical integers.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+let duration = Temporal.Duration.from({
+  microseconds: Number.MAX_SAFE_INTEGER,
+  nanoseconds: 1000,
+});
+
+let time = Temporal.PlainTime.from({
+  microsecond: 1,
+});
+
+let result = time.add(duration);
+
+TemporalHelpers.assertPlainTime(result, 23, 47, 34, 740, 993, 0);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/precision-exact-mathematical-values-2.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/precision-exact-mathematical-values-2.js
new file mode 100644
index 0000000000..857b6acc34
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/precision-exact-mathematical-values-2.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: >
+  Duration components are precise mathematical integers.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+let duration = Temporal.Duration.from({
+  hours: Number.MAX_VALUE,
+  minutes: Number.MAX_VALUE,
+});
+
+let time = new Temporal.PlainTime(0, 0, 0, 0, 0, 0);
+
+let result = time.add(duration);
+
+TemporalHelpers.assertPlainTime(result, 10, 8, 0, 0, 0, 0);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/precision-exact-mathematical-values-3.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/precision-exact-mathematical-values-3.js
new file mode 100644
index 0000000000..0c3f74ef5f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/precision-exact-mathematical-values-3.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: >
+  Duration components are precise mathematical integers.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+let duration = Temporal.Duration.from({
+  hours: Number.MAX_VALUE,
+  minutes: Number.MAX_VALUE,
+  seconds: Number.MAX_VALUE,
+  milliseconds: Number.MAX_VALUE,
+  microseconds: Number.MAX_VALUE,
+  nanoseconds: Number.MAX_VALUE,
+});
+
+let time = new Temporal.PlainTime(0, 0, 0, 0, 0, 0);
+
+let result = time.add(duration);
+
+TemporalHelpers.assertPlainTime(result, 3, 53, 35, 351, 226, 368);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/prop-desc.js
new file mode 100644
index 0000000000..3d644c0f8c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/prop-desc.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: The "add" property of Temporal.PlainTime.prototype
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+assert.sameValue(
+  typeof Temporal.PlainTime.prototype.add,
+  "function",
+  "`typeof PlainTime.prototype.add` is `function`"
+);
+
+verifyProperty(Temporal.PlainTime.prototype, "add", {
+  writable: true,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/subclassing-ignored.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/subclassing-ignored.js
new file mode 100644
index 0000000000..ee8b3f4871
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/add/subclassing-ignored.js
@@ -0,0 +1,20 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.add
+description: Objects of a subclass are never created as return values for add()
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+TemporalHelpers.checkSubclassingIgnored(
+  Temporal.PlainTime,
+  [12, 34, 56, 987, 654, 321],
+  "add",
+  [{ nanoseconds: 1 }],
+  (result) => TemporalHelpers.assertPlainTime(result, 12, 34, 56, 987, 654, 322),
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/calendar/basic.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/calendar/basic.js
new file mode 100644
index 0000000000..3e6a13cc43
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/calendar/basic.js
@@ -0,0 +1,16 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-get-temporal.plaintime.prototype.calendar
+description: calendar returns the iso8601 calendar.
+features: [Temporal]
+---*/
+
+const pt = new Temporal.PlainTime();
+assert(pt.calendar instanceof Temporal.Calendar, "getter returns Calendar object");
+assert.sameValue(pt.calendar.toString(), "iso8601", "getter returns iso8601 calendar");
+assert.sameValue(pt.calendar, pt.calendar, "getter returns the same object");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/calendar/branding.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/calendar/branding.js
new file mode 100644
index 0000000000..70d3e3e739
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/calendar/branding.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-get-temporal.plaintime.prototype.calendar
+description: Throw a TypeError if the receiver is invalid
+features: [Symbol, Temporal]
+---*/
+
+const calendar = Object.getOwnPropertyDescriptor(Temporal.PlainTime.prototype, "calendar").get;
+
+assert.sameValue(typeof calendar, "function");
+
+assert.throws(TypeError, () => calendar.call(undefined), "undefined");
+assert.throws(TypeError, () => calendar.call(null), "null");
+assert.throws(TypeError, () => calendar.call(true), "true");
+assert.throws(TypeError, () => calendar.call(""), "empty string");
+assert.throws(TypeError, () => calendar.call(Symbol()), "symbol");
+assert.throws(TypeError, () => calendar.call(1), "1");
+assert.throws(TypeError, () => calendar.call({}), "plain object");
+assert.throws(TypeError, () => calendar.call(Temporal.PlainTime), "Temporal.PlainTime");
+assert.throws(TypeError, () => calendar.call(Temporal.PlainTime.prototype), "Temporal.PlainTime.prototype");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/calendar/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/calendar/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/calendar/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/calendar/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/calendar/prop-desc.js
new file mode 100644
index 0000000000..600777f4df
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/calendar/prop-desc.js
@@ -0,0 +1,17 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-get-temporal.plaintime.prototype.calendar
+description: The "calendar" property of Temporal.PlainTime.prototype
+features: [Temporal]
+---*/
+
+const descriptor = Object.getOwnPropertyDescriptor(Temporal.PlainTime.prototype, "calendar");
+assert.sameValue(typeof descriptor.get, "function");
+assert.sameValue(descriptor.set, undefined);
+assert.sameValue(descriptor.enumerable, false);
+assert.sameValue(descriptor.configurable, true);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/calendar/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/calendar/shell.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/calendar/shell.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/constructor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/constructor.js
new file mode 100644
index 0000000000..28e3c6f436
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/constructor.js
@@ -0,0 +1,20 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.constructor
+description: Test for Temporal.PlainTime.prototype.constructor.
+info: The initial value of Temporal.PlainTime.prototype.constructor is %Temporal.PlainTime%.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype, "constructor", {
+  value: Temporal.PlainTime,
+  writable: true,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-cast.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-cast.js
new file mode 100644
index 0000000000..9ad32ba51a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-cast.js
@@ -0,0 +1,20 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: equals() casts its argument
+features: [Temporal]
+---*/
+
+const t1 = Temporal.PlainTime.from("08:44:15.321");
+
+assert.sameValue(t1.equals({ hour: 14, minute: 23, second: 30, millisecond: 123 }), false, "object");
+assert.sameValue(t1.equals({ hour: 8, minute: 44, second: 15, millisecond: 321 }), true, "object");
+assert.sameValue(t1.equals("14:23:30.123"), false, "string");
+assert.sameValue(t1.equals("08:44:15.321"), true, "string");
+assert.throws(TypeError, () => t1.equals({}), "no properties");
+assert.throws(TypeError, () => t1.equals({ hours: 8 }), "only plural property");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-number.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-number.js
new file mode 100644
index 0000000000..6e4f1cb2e7
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-number.js
@@ -0,0 +1,33 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: A number is converted to a string, then to Temporal.PlainTime
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const arg = 123456.987654321;
+
+const result = instance.equals(arg);
+assert.sameValue(result, true, "123456.987654321 is a valid ISO string for PlainTime");
+
+const numbers = [
+  1,
+  -123456.987654321,
+  1234567,
+  123456.9876543219,
+];
+
+for (const arg of numbers) {
+  assert.throws(
+    RangeError,
+    () => instance.equals(arg),
+    `Number ${arg} does not convert to a valid ISO string for PlainTime`
+  );
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-calendar-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-calendar-annotation.js
new file mode 100644
index 0000000000..1a6cece33b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-calendar-annotation.js
@@ -0,0 +1,40 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: Various forms of calendar annotation; critical flag has no effect
+features: [Temporal]
+---*/
+
+const tests = [
+  ["12:34:56.987654321[u-ca=iso8601]", "without time zone"],
+  ["12:34:56.987654321[UTC][u-ca=iso8601]", "with time zone"],
+  ["12:34:56.987654321[!u-ca=iso8601]", "with ! and no time zone"],
+  ["12:34:56.987654321[UTC][!u-ca=iso8601]", "with ! and time zone"],
+  ["T12:34:56.987654321[u-ca=iso8601]", "with T and no time zone"],
+  ["T12:34:56.987654321[UTC][u-ca=iso8601]", "with T and time zone"],
+  ["T12:34:56.987654321[!u-ca=iso8601]", "with T, !, and no time zone"],
+  ["T12:34:56.987654321[UTC][!u-ca=iso8601]", "with T, !, and time zone"],
+  ["1970-01-01T12:34:56.987654321[u-ca=iso8601]", "with date and no time zone"],
+  ["1970-01-01T12:34:56.987654321[UTC][u-ca=iso8601]", "with date and time zone"],
+  ["1970-01-01T12:34:56.987654321[!u-ca=iso8601]", "with !, date, and no time zone"],
+  ["1970-01-01T12:34:56.987654321[UTC][!u-ca=iso8601]", "with !, date, and time zone"],
+  ["1970-01-01T12:34:56.987654321[u-ca=iso8601][u-ca=discord]", "second annotation ignored"],
+  ["1970-01-01T12:34:56.987654321[u-ca=iso8601][!u-ca=discord]", "second annotation ignored even with !"],
+];
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+tests.forEach(([arg, description]) => {
+  const result = instance.equals(arg);
+
+  assert.sameValue(
+    result,
+    true,
+    `calendar annotation (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-critical-unknown-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-critical-unknown-annotation.js
new file mode 100644
index 0000000000..22e39509c5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-critical-unknown-annotation.js
@@ -0,0 +1,29 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: Unknown annotations with critical flag are rejected
+features: [Temporal]
+---*/
+
+const invalidStrings = [
+  "00:00[!foo=bar]",
+  "T00:00[!foo=bar]",
+  "1970-01-01T00:00[!foo=bar]",
+  "1970-01-01T00:00[UTC][!foo=bar]",
+  "1970-01-01T00:00[u-ca=iso8601][!foo=bar]",
+  "1970-01-01T00:00[UTC][!foo=bar][u-ca=iso8601]",
+  "1970-01-01T00:00[foo=bar][!_foo-bar0=Dont-Ignore-This-99999999999]",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => instance.equals(arg),
+    `reject unknown annotation with critical flag: ${arg}`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-date-with-utc-offset.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-date-with-utc-offset.js
new file mode 100644
index 0000000000..85c42b673a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-date-with-utc-offset.js
@@ -0,0 +1,52 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: UTC offset not valid with format that does not include a time
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const validStrings = [
+  "12:34:56.987654321+00:00",
+  "12:34:56.987654321+00:00[UTC]",
+  "12:34:56.987654321+00:00[!UTC]",
+  "12:34:56.987654321-02:30[America/St_Johns]",
+  "1976-11-18T12:34:56.987654321+00:00",
+  "1976-11-18T12:34:56.987654321+00:00[UTC]",
+  "1976-11-18T12:34:56.987654321+00:00[!UTC]",
+  "1976-11-18T12:34:56.987654321-02:30[America/St_Johns]",
+];
+
+for (const arg of validStrings) {
+  const result = instance.equals(arg);
+
+  assert.sameValue(
+    result,
+    true,
+    `"${arg}" is a valid UTC offset with time for PlainTime`
+  );
+}
+
+const invalidStrings = [
+  "2022-09-15Z",
+  "2022-09-15Z[UTC]",
+  "2022-09-15Z[Europe/Vienna]",
+  "2022-09-15+00:00",
+  "2022-09-15+00:00[UTC]",
+  "2022-09-15-02:30",
+  "2022-09-15-02:30[America/St_Johns]",
+];
+
+for (const arg of invalidStrings) {
+  assert.throws(
+    RangeError,
+    () => instance.equals(arg),
+    `"${arg}" UTC offset without time is not valid for PlainTime`
+  );
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-multiple-time-zone.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-multiple-time-zone.js
new file mode 100644
index 0000000000..38735e52f4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-multiple-time-zone.js
@@ -0,0 +1,29 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: More than one time zone annotation is not syntactical
+features: [Temporal]
+---*/
+
+const invalidStrings = [
+  "00:00[UTC][UTC]",
+  "T00:00[UTC][UTC]",
+  "1970-01-01T00:00[UTC][UTC]",
+  "1970-01-01T00:00[!UTC][UTC]",
+  "1970-01-01T00:00[UTC][!UTC]",
+  "1970-01-01T00:00[UTC][u-ca=iso8601][UTC]",
+  "1970-01-01T00:00[UTC][foo=bar][UTC]",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => instance.equals(arg),
+    `reject more than one time zone annotation: ${arg}`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-no-implicit-midnight.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-no-implicit-midnight.js
new file mode 100644
index 0000000000..97498bce9f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-no-implicit-midnight.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: RangeError thrown if a date-only string is passed in a PlainTime context
+features: [Temporal, arrow-function]
+---*/
+
+const arg = "2019-10-01";
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+assert.throws(
+  RangeError,
+  () => instance.equals(arg),
+  "Date-only string throws, does not implicitly convert to midnight"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-time-designator-required-for-disambiguation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-time-designator-required-for-disambiguation.js
new file mode 100644
index 0000000000..fff1344146
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-time-designator-required-for-disambiguation.js
@@ -0,0 +1,37 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: ISO 8601 time designator "T" required in cases of ambiguity
+includes: [temporalHelpers.js]
+features: [Temporal, arrow-function]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+TemporalHelpers.ISO.plainTimeStringsAmbiguous().forEach((string) => {
+  let arg = string;
+  assert.throws(
+    RangeError,
+    () => instance.equals(arg),
+    `'${arg}' is ambiguous and requires T prefix`
+  );
+  // The same string with a T prefix should not throw:
+  arg = `T${string}`;
+  instance.equals(arg);
+
+  arg = ` ${string}`;
+  assert.throws(
+    RangeError,
+    () => instance.equals(arg),
+    `space is not accepted as a substitute for T prefix: '${arg}'`
+  );
+});
+
+// None of these should throw without a T prefix, because they are unambiguously time strings:
+TemporalHelpers.ISO.plainTimeStringsUnambiguous().forEach(
+  (arg) => instance.equals(arg));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-time-separators.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-time-separators.js
new file mode 100644
index 0000000000..0c8bf77d17
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-time-separators.js
@@ -0,0 +1,31 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: Time separator in string argument can vary
+features: [Temporal]
+---*/
+
+const tests = [
+  ["1976-11-18T12:34:56.987654321", "uppercase T"],
+  ["1976-11-18t12:34:56.987654321", "lowercase T"],
+  ["1976-11-18 12:34:56.987654321", "space between date and time"],
+  ["T12:34:56.987654321", "time-only uppercase T"],
+  ["t12:34:56.987654321", "time-only lowercase T"],
+];
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+tests.forEach(([arg, description]) => {
+  const result = instance.equals(arg);
+
+  assert.sameValue(
+    result,
+    true,
+    `variant time separators (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-time-zone-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-time-zone-annotation.js
new file mode 100644
index 0000000000..b418c1f23c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-time-zone-annotation.js
@@ -0,0 +1,50 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: Various forms of time zone annotation; critical flag has no effect
+features: [Temporal]
+---*/
+
+const tests = [
+  ["12:34:56.987654321[Asia/Kolkata]", "named, with no offset"],
+  ["12:34:56.987654321[!Europe/Vienna]", "named, with ! and no offset"],
+  ["12:34:56.987654321[+00:00]", "numeric, with no offset"],
+  ["12:34:56.987654321[!-02:30]", "numeric, with ! and no offset"],
+  ["T12:34:56.987654321[UTC]", "named, with T and no offset"],
+  ["T12:34:56.987654321[!Africa/Abidjan]", "named, with T, !, and no offset"],
+  ["T12:34:56.987654321[+01:00]", "numeric, with T and no offset"],
+  ["T12:34:56.987654321[!-08:00]", "numeric, with T, !, and no offset"],
+  ["12:34:56.987654321+00:00[America/Sao_Paulo]", "named, with offset"],
+  ["12:34:56.987654321+00:00[!Asia/Tokyo]", "named, with ! and offset"],
+  ["12:34:56.987654321+00:00[-02:30]", "numeric, with offset"],
+  ["12:34:56.987654321+00:00[!+00:00]", "numeric, with ! and offset"],
+  ["T12:34:56.987654321+00:00[America/New_York]", "named, with T and offset"],
+  ["T12:34:56.987654321+00:00[!UTC]", "named, with T, !, and offset"],
+  ["T12:34:56.987654321+00:00[-08:00]", "numeric, with T and offset"],
+  ["T12:34:56.987654321+00:00[!+01:00]", "numeric, with T, !, and offset"],
+  ["1970-01-01T12:34:56.987654321[Africa/Lagos]", "named, with date and no offset"],
+  ["1970-01-01T12:34:56.987654321[!America/Vancouver]", "named, with date, !, and no offset"],
+  ["1970-01-01T12:34:56.987654321[+00:00]", "numeric, with date and no offset"],
+  ["1970-01-01T12:34:56.987654321[!-02:30]", "numeric, with date, !, and no offset"],
+  ["1970-01-01T12:34:56.987654321+00:00[Europe/London]", "named, with date and offset"],
+  ["1970-01-01T12:34:56.987654321+00:00[!Asia/Seoul]", "named, with date, offset, and !"],
+  ["1970-01-01T12:34:56.987654321+00:00[+01:00]", "numeric, with date and offset"],
+  ["1970-01-01T12:34:56.987654321+00:00[!-08:00]", "numeric, with date, offset, and !"],
+];
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+tests.forEach(([arg, description]) => {
+  const result = instance.equals(arg);
+
+  assert.sameValue(
+    result,
+    true,
+    `time zone annotation (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-unknown-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-unknown-annotation.js
new file mode 100644
index 0000000000..f3c894c149
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-unknown-annotation.js
@@ -0,0 +1,39 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: Various forms of unknown annotation
+features: [Temporal]
+---*/
+
+const tests = [
+  ["12:34:56.987654321[foo=bar]", "alone"],
+  ["12:34:56.987654321[UTC][foo=bar]", "with time zone"],
+  ["12:34:56.987654321[u-ca=iso8601][foo=bar]", "with calendar"],
+  ["12:34:56.987654321[UTC][foo=bar][u-ca=iso8601]", "with time zone and calendar"],
+  ["T12:34:56.987654321[foo=bar]", "with T"],
+  ["T12:34:56.987654321[UTC][foo=bar]", "with T and time zone"],
+  ["T12:34:56.987654321[u-ca=iso8601][foo=bar]", "with T and calendar"],
+  ["T12:34:56.987654321[UTC][foo=bar][u-ca=iso8601]", "with T, time zone, and calendar"],
+  ["1970-01-01T12:34:56.987654321[foo=bar]", "with date"],
+  ["1970-01-01T12:34:56.987654321[UTC][foo=bar]", "with date and time zone"],
+  ["1970-01-01T12:34:56.987654321[u-ca=iso8601][foo=bar]", "with date and calendar"],
+  ["1970-01-01T12:34:56.987654321[UTC][foo=bar][u-ca=iso8601]", "with date, time zone, and calendar"],
+  ["1970-01-01T12:34:56.987654321[foo=bar][_foo-bar0=Ignore-This-999999999999]", "with another unknown annotation"],
+];
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+tests.forEach(([arg, description]) => {
+  const result = instance.equals(arg);
+
+  assert.sameValue(
+    result,
+    true,
+    `unknown annotation (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-with-time-designator.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-with-time-designator.js
new file mode 100644
index 0000000000..b86dfccb79
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-with-time-designator.js
@@ -0,0 +1,31 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: ISO 8601 time designator "T" allowed at the start of PlainTime strings
+features: [Temporal, arrow-function]
+---*/
+
+const instance = new Temporal.PlainTime(0, 30, 0, 0, 0, 0);
+const validStrings = [
+  "T00:30",
+  "t00:30",
+  "T0030",
+  "t0030",
+  "T00:30:00",
+  "t00:30:00",
+  "T003000",
+  "t003000",
+  "T00:30:00.000000000",
+  "t00:30:00.000000000",
+  "T003000.000000000",
+  "t003000.000000000",
+];
+validStrings.forEach((arg) => {
+  const result = instance.equals(arg);
+  assert.sameValue(result, true, `T prefix is accepted: ${arg}`);
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-with-utc-designator.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-with-utc-designator.js
new file mode 100644
index 0000000000..354f03d573
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-string-with-utc-designator.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: RangeError thrown if a string with UTC designator is used as a PlainTime
+features: [Temporal, arrow-function]
+---*/
+
+const invalidStrings = [
+  "2019-10-01T09:00:00Z",
+  "2019-10-01T09:00:00Z[UTC]",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => instance.equals(arg),
+    "String with UTC designator should not be valid as a PlainTime"
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-wrong-type.js
new file mode 100644
index 0000000000..4885435055
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-wrong-type.js
@@ -0,0 +1,39 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: >
+  Appropriate error thrown when argument cannot be converted to a valid string
+  or property bag for PlainTime
+features: [BigInt, Symbol, Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const rangeErrorTests = [
+  [undefined, "undefined"],
+  [null, "null"],
+  [true, "boolean"],
+  ["", "empty string"],
+  [1, "number that doesn't convert to a valid ISO string"],
+  [1n, "bigint"],
+];
+
+for (const [arg, description] of rangeErrorTests) {
+  assert.throws(RangeError, () => instance.equals(arg), `${description} does not convert to a valid ISO string`);
+}
+
+const typeErrorTests = [
+  [Symbol(), "symbol"],
+  [{}, "plain object"],
+  [Temporal.PlainTime, "Temporal.PlainTime, object"],
+  [Temporal.PlainTime.prototype, "Temporal.PlainTime.prototype, object"],
+];
+
+for (const [arg, description] of typeErrorTests) {
+  assert.throws(TypeError, () => instance.equals(arg), `${description} is not a valid property bag and does not convert to a string`);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-zoneddatetime-balance-negative-time-units.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-zoneddatetime-balance-negative-time-units.js
new file mode 100644
index 0000000000..1c9376d117
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-zoneddatetime-balance-negative-time-units.js
@@ -0,0 +1,43 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: Negative time fields are balanced upwards if the argument is given as ZonedDateTime
+info: |
+    sec-temporal-balancetime steps 3–14:
+      3. Set _microsecond_ to _microsecond_ + floor(_nanosecond_ / 1000).
+      4. Set _nanosecond_ to _nanosecond_ modulo 1000.
+      5. Set _millisecond_ to _millisecond_ + floor(_microsecond_ / 1000).
+      6. Set _microsecond_ to _microsecond_ modulo 1000.
+      7. Set _second_ to _second_ + floor(_millisecond_ / 1000).
+      8. Set _millisecond_ to _millisecond_ modulo 1000.
+      9. Set _minute_ to _minute_ + floor(_second_ / 60).
+      10. Set _second_ to _second_ modulo 60.
+      11. Set _hour_ to _hour_ + floor(_minute_ / 60).
+      12. Set _minute_ to _minute_ modulo 60.
+      13. Let _days_ be floor(_hour_ / 24).
+      14. Set _hour_ to _hour_ modulo 24.
+    sec-temporal-balanceisodatetime step 1:
+      1. Let _balancedTime_ be ? BalanceTime(_hour_, _minute_, _second_, _millisecond_, _microsecond_, _nanosecond_).
+    sec-temporal-builtintimezonegetplaindatetimefor step 3:
+      3. Set _result_ to ? BalanceISODateTime(_result_.[[Year]], _result_.[[Month]], _result_.[[Day]], _result_.[[Hour]], _result_.[[Minute]], _result_.[[Second]], _result_.[[Millisecond]], _result_.[[Microsecond]], _result_.[[Nanosecond]] + _offsetNanoseconds_).
+    sec-temporal-totemporaltime step 3.b:
+      b. If _item_ has an [[InitializedTemporalZonedDateTime]] internal slot, then
+        ...
+        ii. 1. Set _plainDateTime_ to ? BuiltinTimeZoneGetPlainDateTimeFor(_item_.[[TimeZone]], _instant_, _item_.[[Calendar]]).
+    sec-temporal.plaintime.prototype.equals step 3:
+      3. Set _other_ to ? ToTemporalTime(_other_).
+features: [Temporal]
+---*/
+
+// This code path is encountered if the time zone offset is negative and its
+// absolute value in nanoseconds is greater than the nanosecond field of the
+// exact time's epoch parts
+const tz = new Temporal.TimeZone("-00:00:00.000000002");
+const datetime = new Temporal.ZonedDateTime(3661_001_001_001n, tz);
+
+assert(new Temporal.PlainTime(1, 1, 1, 1, 0, 999).equals(datetime));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-zoneddatetime-negative-epochnanoseconds.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-zoneddatetime-negative-epochnanoseconds.js
new file mode 100644
index 0000000000..c10a2222c2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-zoneddatetime-negative-epochnanoseconds.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: A pre-epoch value is handled correctly by the modulo operation in GetISOPartsFromEpoch
+info: |
+    sec-temporal-getisopartsfromepoch step 1:
+      1. Let _remainderNs_ be the mathematical value whose sign is the sign of _epochNanoseconds_ and whose magnitude is abs(_epochNanoseconds_) modulo 10<sup>6</sup>.
+    sec-temporal-builtintimezonegetplaindatetimefor step 2:
+      2. Let _result_ be ! GetISOPartsFromEpoch(_instant_.[[Nanoseconds]]).
+features: [Temporal]
+---*/
+
+const datetime = new Temporal.ZonedDateTime(-13849764_999_999_999n, "UTC");
+
+// This code path shows up anywhere we convert an exact time, before the Unix
+// epoch, with nonzero microseconds or nanoseconds, into a wall time.
+
+const instance = new Temporal.PlainTime(16, 50, 35, 0, 0, 1);
+const result = instance.equals(datetime);
+assert.sameValue(result, true);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-non-integer.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-non-integer.js
new file mode 100644
index 0000000000..5719f46da8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-non-integer.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: RangeError thrown if time zone reports an offset that is not an integer number of nanoseconds
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[3600_000_000_000.5, NaN, -Infinity, Infinity].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  assert.throws(RangeError, () => time.equals(datetime));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js
new file mode 100644
index 0000000000..dddeee36ad
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js
@@ -0,0 +1,23 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: TypeError thrown if timeZone.getOffsetNanosecondsFor is not callable
+features: [BigInt, Symbol, Temporal, arrow-function]
+---*/
+
+[undefined, null, true, Math.PI, 'string', Symbol('sym'), 42n, {}].forEach((notCallable) => {
+  const timeZone = new Temporal.TimeZone("UTC");
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  timeZone.getOffsetNanosecondsFor = notCallable;
+  assert.throws(
+    TypeError,
+    () => time.equals(datetime),
+    `Uncallable ${notCallable === null ? 'null' : typeof notCallable} getOffsetNanosecondsFor should throw TypeError`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-out-of-range.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-out-of-range.js
new file mode 100644
index 0000000000..ab47d2ccda
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-out-of-range.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: RangeError thrown if time zone reports an offset that is out of range
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[-86400_000_000_000, 86400_000_000_000].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  assert.throws(RangeError, () => time.equals(datetime));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-wrong-type.js
new file mode 100644
index 0000000000..c85d96fbc4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-wrong-type.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: TypeError thrown if time zone reports an offset that is not a Number
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[
+  undefined,
+  null,
+  true,
+  "+01:00",
+  Symbol(),
+  3600_000_000_000n,
+  {},
+  { valueOf() { return 3600_000_000_000; } },
+].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  assert.throws(TypeError, () => time.equals(datetime));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/basic.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/basic.js
new file mode 100644
index 0000000000..e391f8e1dd
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/basic.js
@@ -0,0 +1,18 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: Basic tests for equals()
+features: [Temporal]
+---*/
+
+const t1 = Temporal.PlainTime.from("08:44:15.321");
+const t1bis = Temporal.PlainTime.from("08:44:15.321");
+const t2 = Temporal.PlainTime.from("14:23:30.123");
+assert.sameValue(t1.equals(t1), true, "same object");
+assert.sameValue(t1.equals(t1bis), true, "different object");
+assert.sameValue(t1.equals(t2), false, "different times");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/branding.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/branding.js
new file mode 100644
index 0000000000..1551730ac3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/branding.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: Throw a TypeError if the receiver is invalid
+features: [Symbol, Temporal]
+---*/
+
+const equals = Temporal.PlainTime.prototype.equals;
+
+assert.sameValue(typeof equals, "function");
+
+const args = [new Temporal.PlainTime(12)];
+
+assert.throws(TypeError, () => equals.apply(undefined, args), "undefined");
+assert.throws(TypeError, () => equals.apply(null, args), "null");
+assert.throws(TypeError, () => equals.apply(true, args), "true");
+assert.throws(TypeError, () => equals.apply("", args), "empty string");
+assert.throws(TypeError, () => equals.apply(Symbol(), args), "symbol");
+assert.throws(TypeError, () => equals.apply(1, args), "1");
+assert.throws(TypeError, () => equals.apply({}, args), "plain object");
+assert.throws(TypeError, () => equals.apply(Temporal.PlainTime, args), "Temporal.PlainTime");
+assert.throws(TypeError, () => equals.apply(Temporal.PlainTime.prototype, args), "Temporal.PlainTime.prototype");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/builtin.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/builtin.js
new file mode 100644
index 0000000000..14bdeb760a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/builtin.js
@@ -0,0 +1,36 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: >
+    Tests that Temporal.PlainTime.prototype.equals
+    meets the requirements for built-in objects defined by the
+    introduction of chapter 17 of the ECMAScript Language Specification.
+info: |
+    Built-in functions that are not constructors do not have a "prototype" property unless
+    otherwise specified in the description of a particular function.
+
+    Unless specified otherwise, a built-in object that is callable as a function is a built-in
+    function object with the characteristics described in 10.3. Unless specified otherwise, the
+    [[Extensible]] internal slot of a built-in object initially has the value true.
+
+    Unless otherwise specified every built-in function and every built-in constructor has the
+    Function prototype object [...] as the value of its [[Prototype]] internal slot.
+features: [Temporal]
+---*/
+
+assert.sameValue(Object.isExtensible(Temporal.PlainTime.prototype.equals),
+  true, "Built-in objects must be extensible.");
+
+assert.sameValue(Object.prototype.toString.call(Temporal.PlainTime.prototype.equals),
+  "[object Function]", "Object.prototype.toString");
+
+assert.sameValue(Object.getPrototypeOf(Temporal.PlainTime.prototype.equals),
+  Function.prototype, "prototype");
+
+assert.sameValue(Temporal.PlainTime.prototype.equals.hasOwnProperty("prototype"),
+  false, "prototype property");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/calendar-temporal-object.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/calendar-temporal-object.js
new file mode 100644
index 0000000000..e0295c5d33
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/calendar-temporal-object.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: Fast path for converting other Temporal objects to Temporal.Calendar by reading internal slots
+info: |
+    sec-temporal.plaintime.prototype.equals step 3:
+      3. Set _other_ to ? ToTemporalTime(_other_).
+    sec-temporal-totemporaltime step 3.d:
+      d. If _calendar_ is not *undefined*, then
+        i. Set _calendar_ to ? ToTemporalCalendar(_calendar_).
+        ii. If ? ToString(_calendar_) is not *"iso8601"*, then
+          1. Throw a *RangeError* exception.
+    sec-temporal-totemporalcalendar step 1.a:
+      a. If _temporalCalendarLike_ has an [[InitializedTemporalDate]], [[InitializedTemporalDateTime]], [[InitializedTemporalMonthDay]], [[InitializedTemporalYearMonth]], or [[InitializedTemporalZonedDateTime]] internal slot, then
+        i. Return _temporalCalendarLike_.[[Calendar]].
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+TemporalHelpers.checkToTemporalCalendarFastPath((temporalObject) => {
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  assert.throws(RangeError, () => time.equals({ hour: 12, minute: 30, calendar: temporalObject }));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/leap-second.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/leap-second.js
new file mode 100644
index 0000000000..864c437dd2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/leap-second.js
@@ -0,0 +1,29 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: Leap second is a valid ISO string for PlainTime
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(23, 59, 59);
+
+let arg = "2016-12-31T23:59:60";
+const result1 = instance.equals(arg);
+assert.sameValue(
+  result1,
+  true,
+  "leap second is a valid ISO string for PlainTime"
+);
+
+arg = { year: 2016, month: 12, day: 31, hour: 23, minute: 59, second: 60 };
+const result2 = instance.equals(arg);
+assert.sameValue(
+  result2,
+  true,
+  "second: 60 is ignored in property bag for PlainTime"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/length.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/length.js
new file mode 100644
index 0000000000..8842dce86d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/length.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: Temporal.PlainTime.prototype.equals.length is 1
+info: |
+    Every built-in function object, including constructors, has a "length" property whose value is
+    an integer. Unless otherwise specified, this value is equal to the largest number of named
+    arguments shown in the subclause headings for the function description. Optional parameters
+    (which are indicated with brackets: [ ]) or rest parameters (which are shown using the form
+    «...name») are not included in the default argument count.
+
+    Unless otherwise specified, the "length" property of a built-in function object has the
+    attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.equals, "length", {
+  value: 1,
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/name.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/name.js
new file mode 100644
index 0000000000..e5f188b73c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/name.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: Temporal.PlainTime.prototype.equals.name is "equals".
+info: |
+    Every built-in function object, including constructors, that is not identified as an anonymous
+    function has a "name" property whose value is a String. Unless otherwise specified, this value
+    is the name that is given to the function in this specification.
+
+    Unless otherwise specified, the "name" property of a built-in function object, if it exists,
+    has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.equals, "name", {
+  value: "equals",
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/not-a-constructor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/not-a-constructor.js
new file mode 100644
index 0000000000..11d55bd1ed
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/not-a-constructor.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: >
+  Temporal.PlainTime.prototype.equals does not implement [[Construct]], is not new-able
+info: |
+    Built-in function objects that are not identified as constructors do not implement the
+    [[Construct]] internal method unless otherwise specified in the description of a particular
+    function.
+includes: [isConstructor.js]
+features: [Reflect.construct, Temporal]
+---*/
+
+assert.throws(TypeError, () => {
+  new Temporal.PlainTime.prototype.equals();
+}, "Calling as constructor");
+
+assert.sameValue(isConstructor(Temporal.PlainTime.prototype.equals), false,
+  "isConstructor(Temporal.PlainTime.prototype.equals)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/plaintime-propertybag-no-time-units.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/plaintime-propertybag-no-time-units.js
new file mode 100644
index 0000000000..55efac1801
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/plaintime-propertybag-no-time-units.js
@@ -0,0 +1,20 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: Missing time units in property bag default to 0
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(0, 30, 0, 0, 0, 0);
+
+const props = {};
+assert.throws(TypeError, () => instance.equals(props), "TypeError if no properties are present");
+
+props.minute = 30;
+const result = instance.equals(props);
+assert.sameValue(result, true, "missing time units default to 0");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/prop-desc.js
new file mode 100644
index 0000000000..da054b2b3f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/prop-desc.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: The "equals" property of Temporal.PlainTime.prototype
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+assert.sameValue(
+  typeof Temporal.PlainTime.prototype.equals,
+  "function",
+  "`typeof PlainTime.prototype.equals` is `function`"
+);
+
+verifyProperty(Temporal.PlainTime.prototype, "equals", {
+  writable: true,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/year-zero.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/year-zero.js
new file mode 100644
index 0000000000..c5932c004c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/equals/year-zero.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.equals
+description: Negative zero, as an extended year, is rejected
+features: [Temporal, arrow-function]
+---*/
+
+const invalidStrings = [
+  "-000000-12-07T03:24:30",
+  "-000000-12-07T03:24:30+01:00",
+  "-000000-12-07T03:24:30+00:00[UTC]",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => instance.equals(arg),
+    "reject minus zero as extended year"
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/branding.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/branding.js
new file mode 100644
index 0000000000..22ff00a63e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/branding.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.getisofields
+description: Throw a TypeError if the receiver is invalid
+features: [Symbol, Temporal]
+---*/
+
+const getISOFields = Temporal.PlainTime.prototype.getISOFields;
+
+assert.sameValue(typeof getISOFields, "function");
+
+assert.throws(TypeError, () => getISOFields.call(undefined), "undefined");
+assert.throws(TypeError, () => getISOFields.call(null), "null");
+assert.throws(TypeError, () => getISOFields.call(true), "true");
+assert.throws(TypeError, () => getISOFields.call(""), "empty string");
+assert.throws(TypeError, () => getISOFields.call(Symbol()), "symbol");
+assert.throws(TypeError, () => getISOFields.call(1), "1");
+assert.throws(TypeError, () => getISOFields.call({}), "plain object");
+assert.throws(TypeError, () => getISOFields.call(Temporal.PlainTime), "Temporal.PlainTime");
+assert.throws(TypeError, () => getISOFields.call(Temporal.PlainTime.prototype), "Temporal.PlainTime.prototype");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/builtin.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/builtin.js
new file mode 100644
index 0000000000..7d71500ec9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/builtin.js
@@ -0,0 +1,36 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.getisofields
+description: >
+    Tests that Temporal.PlainTime.prototype.getISOFields
+    meets the requirements for built-in objects defined by the
+    introduction of chapter 17 of the ECMAScript Language Specification.
+info: |
+    Built-in functions that are not constructors do not have a "prototype" property unless
+    otherwise specified in the description of a particular function.
+
+    Unless specified otherwise, a built-in object that is callable as a function is a built-in
+    function object with the characteristics described in 10.3. Unless specified otherwise, the
+    [[Extensible]] internal slot of a built-in object initially has the value true.
+
+    Unless otherwise specified every built-in function and every built-in constructor has the
+    Function prototype object [...] as the value of its [[Prototype]] internal slot.
+features: [Temporal]
+---*/
+
+assert.sameValue(Object.isExtensible(Temporal.PlainTime.prototype.getISOFields),
+  true, "Built-in objects must be extensible.");
+
+assert.sameValue(Object.prototype.toString.call(Temporal.PlainTime.prototype.getISOFields),
+  "[object Function]", "Object.prototype.toString");
+
+assert.sameValue(Object.getPrototypeOf(Temporal.PlainTime.prototype.getISOFields),
+  Function.prototype, "prototype");
+
+assert.sameValue(Temporal.PlainTime.prototype.getISOFields.hasOwnProperty("prototype"),
+  false, "prototype property");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/custom.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/custom.js
new file mode 100644
index 0000000000..fa09d9bf82
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/custom.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.getisofields
+description: getISOFields does not call into user code.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const calendar = TemporalHelpers.calendarThrowEverything();
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321, calendar);
+const result = instance.getISOFields();
+
+assert.sameValue(result.isoHour, 12, "isoHour result");
+assert.sameValue(result.isoMinute, 34, "isoMinute result");
+assert.sameValue(result.isoSecond, 56, "isoSecond result");
+assert.sameValue(result.isoMillisecond, 987, "isoMillisecond result");
+assert.sameValue(result.isoMicrosecond, 654, "isoMicrosecond result");
+assert.sameValue(result.isoNanosecond, 321, "isoNanosecond result");
+assert.sameValue(result.calendar.id, "iso8601", "calendar result");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/field-names.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/field-names.js
new file mode 100644
index 0000000000..57101281b5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/field-names.js
@@ -0,0 +1,22 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.getisofields
+description: Correct field names on the object returned from getISOFields
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const result = time.getISOFields();
+assert.sameValue(result.isoHour, 12, "isoHour result");
+assert.sameValue(result.isoMinute, 34, "isoMinute result");
+assert.sameValue(result.isoSecond, 56, "isoSecond result");
+assert.sameValue(result.isoMillisecond, 987, "isoMillisecond result");
+assert.sameValue(result.isoMicrosecond, 654, "isoMicrosecond result");
+assert.sameValue(result.isoNanosecond, 321, "isoNanosecond result");
+assert.sameValue(result.calendar.id, "iso8601", "calendar result");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/field-prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/field-prop-desc.js
new file mode 100644
index 0000000000..81345ba910
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/field-prop-desc.js
@@ -0,0 +1,33 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.getisofields
+description: Properties on the returned object have the correct descriptor
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+const expected = [
+  "calendar",
+  "isoHour",
+  "isoMicrosecond",
+  "isoMillisecond",
+  "isoMinute",
+  "isoNanosecond",
+  "isoSecond",
+];
+
+const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+const result = time.getISOFields();
+
+for (const property of expected) {
+  verifyProperty(result, property, {
+    writable: true,
+    enumerable: true,
+    configurable: true,
+  });
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/field-traversal-order.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/field-traversal-order.js
new file mode 100644
index 0000000000..efad885cb7
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/field-traversal-order.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.getisofields
+description: Properties added in correct order to object returned from getISOFields
+includes: [compareArray.js]
+features: [Temporal]
+---*/
+
+const expected = [
+  "calendar",
+  "isoHour",
+  "isoMicrosecond",
+  "isoMillisecond",
+  "isoMinute",
+  "isoNanosecond",
+  "isoSecond",
+];
+
+const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+const result = time.getISOFields();
+
+assert.compareArray(Object.keys(result), expected);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/length.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/length.js
new file mode 100644
index 0000000000..90d423f298
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/length.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.getisofields
+description: Temporal.PlainTime.prototype.getISOFields.length is 0
+info: |
+    Every built-in function object, including constructors, has a "length" property whose value is
+    an integer. Unless otherwise specified, this value is equal to the largest number of named
+    arguments shown in the subclause headings for the function description. Optional parameters
+    (which are indicated with brackets: [ ]) or rest parameters (which are shown using the form
+    «...name») are not included in the default argument count.
+
+    Unless otherwise specified, the "length" property of a built-in function object has the
+    attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.getISOFields, "length", {
+  value: 0,
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/name.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/name.js
new file mode 100644
index 0000000000..8ef16c432c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/name.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.getisofields
+description: Temporal.PlainTime.prototype.getISOFields.name is "getISOFields".
+info: |
+    Every built-in function object, including constructors, that is not identified as an anonymous
+    function has a "name" property whose value is a String. Unless otherwise specified, this value
+    is the name that is given to the function in this specification.
+
+    Unless otherwise specified, the "name" property of a built-in function object, if it exists,
+    has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.getISOFields, "name", {
+  value: "getISOFields",
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/not-a-constructor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/not-a-constructor.js
new file mode 100644
index 0000000000..609fb50873
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/not-a-constructor.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.getisofields
+description: >
+  Temporal.PlainTime.prototype.getISOFields does not implement [[Construct]], is not new-able
+info: |
+    Built-in function objects that are not identified as constructors do not implement the
+    [[Construct]] internal method unless otherwise specified in the description of a particular
+    function.
+includes: [isConstructor.js]
+features: [Reflect.construct, Temporal]
+---*/
+
+assert.throws(TypeError, () => {
+  new Temporal.PlainTime.prototype.getISOFields();
+}, "Calling as constructor");
+
+assert.sameValue(isConstructor(Temporal.PlainTime.prototype.getISOFields), false,
+  "isConstructor(Temporal.PlainTime.prototype.getISOFields)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/prop-desc.js
new file mode 100644
index 0000000000..005eb70a9d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/prop-desc.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.getisofields
+description: The "getISOFields" property of Temporal.PlainTime.prototype
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+assert.sameValue(
+  typeof Temporal.PlainTime.prototype.getISOFields,
+  "function",
+  "`typeof PlainTime.prototype.getISOFields` is `function`"
+);
+
+verifyProperty(Temporal.PlainTime.prototype, "getISOFields", {
+  writable: true,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/prototype.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/prototype.js
new file mode 100644
index 0000000000..83fffc9941
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/prototype.js
@@ -0,0 +1,15 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.getisofields
+description: Correct prototype on the object returned from getISOFields
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+const result = instance.getISOFields();
+assert.sameValue(Object.getPrototypeOf(result), Object.prototype, "prototype");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/getISOFields/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/hour/branding.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/hour/branding.js
new file mode 100644
index 0000000000..95988a8845
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/hour/branding.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-get-temporal.plaintime.prototype.hour
+description: Throw a TypeError if the receiver is invalid
+features: [Symbol, Temporal]
+---*/
+
+const hour = Object.getOwnPropertyDescriptor(Temporal.PlainTime.prototype, "hour").get;
+
+assert.sameValue(typeof hour, "function");
+
+assert.throws(TypeError, () => hour.call(undefined), "undefined");
+assert.throws(TypeError, () => hour.call(null), "null");
+assert.throws(TypeError, () => hour.call(true), "true");
+assert.throws(TypeError, () => hour.call(""), "empty string");
+assert.throws(TypeError, () => hour.call(Symbol()), "symbol");
+assert.throws(TypeError, () => hour.call(1), "1");
+assert.throws(TypeError, () => hour.call({}), "plain object");
+assert.throws(TypeError, () => hour.call(Temporal.PlainTime), "Temporal.PlainTime");
+assert.throws(TypeError, () => hour.call(Temporal.PlainTime.prototype), "Temporal.PlainTime.prototype");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/hour/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/hour/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/hour/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/hour/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/hour/prop-desc.js
new file mode 100644
index 0000000000..6277fd4941
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/hour/prop-desc.js
@@ -0,0 +1,17 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-get-temporal.plaintime.prototype.hour
+description: The "hour" property of Temporal.PlainTime.prototype
+features: [Temporal]
+---*/
+
+const descriptor = Object.getOwnPropertyDescriptor(Temporal.PlainTime.prototype, "hour");
+assert.sameValue(typeof descriptor.get, "function");
+assert.sameValue(descriptor.set, undefined);
+assert.sameValue(descriptor.enumerable, false);
+assert.sameValue(descriptor.configurable, true);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/hour/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/hour/shell.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/hour/shell.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/microsecond/branding.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/microsecond/branding.js
new file mode 100644
index 0000000000..07e2120532
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/microsecond/branding.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-get-temporal.plaintime.prototype.microsecond
+description: Throw a TypeError if the receiver is invalid
+features: [Symbol, Temporal]
+---*/
+
+const microsecond = Object.getOwnPropertyDescriptor(Temporal.PlainTime.prototype, "microsecond").get;
+
+assert.sameValue(typeof microsecond, "function");
+
+assert.throws(TypeError, () => microsecond.call(undefined), "undefined");
+assert.throws(TypeError, () => microsecond.call(null), "null");
+assert.throws(TypeError, () => microsecond.call(true), "true");
+assert.throws(TypeError, () => microsecond.call(""), "empty string");
+assert.throws(TypeError, () => microsecond.call(Symbol()), "symbol");
+assert.throws(TypeError, () => microsecond.call(1), "1");
+assert.throws(TypeError, () => microsecond.call({}), "plain object");
+assert.throws(TypeError, () => microsecond.call(Temporal.PlainTime), "Temporal.PlainTime");
+assert.throws(TypeError, () => microsecond.call(Temporal.PlainTime.prototype), "Temporal.PlainTime.prototype");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/microsecond/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/microsecond/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/microsecond/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/microsecond/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/microsecond/prop-desc.js
new file mode 100644
index 0000000000..7b299f3827
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/microsecond/prop-desc.js
@@ -0,0 +1,17 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-get-temporal.plaintime.prototype.microsecond
+description: The "microsecond" property of Temporal.PlainTime.prototype
+features: [Temporal]
+---*/
+
+const descriptor = Object.getOwnPropertyDescriptor(Temporal.PlainTime.prototype, "microsecond");
+assert.sameValue(typeof descriptor.get, "function");
+assert.sameValue(descriptor.set, undefined);
+assert.sameValue(descriptor.enumerable, false);
+assert.sameValue(descriptor.configurable, true);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/microsecond/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/microsecond/shell.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/microsecond/shell.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/millisecond/branding.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/millisecond/branding.js
new file mode 100644
index 0000000000..1d8473f875
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/millisecond/branding.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-get-temporal.plaintime.prototype.millisecond
+description: Throw a TypeError if the receiver is invalid
+features: [Symbol, Temporal]
+---*/
+
+const millisecond = Object.getOwnPropertyDescriptor(Temporal.PlainTime.prototype, "millisecond").get;
+
+assert.sameValue(typeof millisecond, "function");
+
+assert.throws(TypeError, () => millisecond.call(undefined), "undefined");
+assert.throws(TypeError, () => millisecond.call(null), "null");
+assert.throws(TypeError, () => millisecond.call(true), "true");
+assert.throws(TypeError, () => millisecond.call(""), "empty string");
+assert.throws(TypeError, () => millisecond.call(Symbol()), "symbol");
+assert.throws(TypeError, () => millisecond.call(1), "1");
+assert.throws(TypeError, () => millisecond.call({}), "plain object");
+assert.throws(TypeError, () => millisecond.call(Temporal.PlainTime), "Temporal.PlainTime");
+assert.throws(TypeError, () => millisecond.call(Temporal.PlainTime.prototype), "Temporal.PlainTime.prototype");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/millisecond/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/millisecond/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/millisecond/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/millisecond/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/millisecond/prop-desc.js
new file mode 100644
index 0000000000..fd864af190
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/millisecond/prop-desc.js
@@ -0,0 +1,17 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-get-temporal.plaintime.prototype.millisecond
+description: The "millisecond" property of Temporal.PlainTime.prototype
+features: [Temporal]
+---*/
+
+const descriptor = Object.getOwnPropertyDescriptor(Temporal.PlainTime.prototype, "millisecond");
+assert.sameValue(typeof descriptor.get, "function");
+assert.sameValue(descriptor.set, undefined);
+assert.sameValue(descriptor.enumerable, false);
+assert.sameValue(descriptor.configurable, true);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/millisecond/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/millisecond/shell.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/millisecond/shell.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/minute/branding.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/minute/branding.js
new file mode 100644
index 0000000000..b84acfb757
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/minute/branding.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-get-temporal.plaintime.prototype.minute
+description: Throw a TypeError if the receiver is invalid
+features: [Symbol, Temporal]
+---*/
+
+const minute = Object.getOwnPropertyDescriptor(Temporal.PlainTime.prototype, "minute").get;
+
+assert.sameValue(typeof minute, "function");
+
+assert.throws(TypeError, () => minute.call(undefined), "undefined");
+assert.throws(TypeError, () => minute.call(null), "null");
+assert.throws(TypeError, () => minute.call(true), "true");
+assert.throws(TypeError, () => minute.call(""), "empty string");
+assert.throws(TypeError, () => minute.call(Symbol()), "symbol");
+assert.throws(TypeError, () => minute.call(1), "1");
+assert.throws(TypeError, () => minute.call({}), "plain object");
+assert.throws(TypeError, () => minute.call(Temporal.PlainTime), "Temporal.PlainTime");
+assert.throws(TypeError, () => minute.call(Temporal.PlainTime.prototype), "Temporal.PlainTime.prototype");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/minute/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/minute/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/minute/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/minute/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/minute/prop-desc.js
new file mode 100644
index 0000000000..03b55d78d3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/minute/prop-desc.js
@@ -0,0 +1,17 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-get-temporal.plaintime.prototype.minute
+description: The "minute" property of Temporal.PlainTime.prototype
+features: [Temporal]
+---*/
+
+const descriptor = Object.getOwnPropertyDescriptor(Temporal.PlainTime.prototype, "minute");
+assert.sameValue(typeof descriptor.get, "function");
+assert.sameValue(descriptor.set, undefined);
+assert.sameValue(descriptor.enumerable, false);
+assert.sameValue(descriptor.configurable, true);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/minute/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/minute/shell.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/minute/shell.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/nanosecond/branding.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/nanosecond/branding.js
new file mode 100644
index 0000000000..d46b5befb4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/nanosecond/branding.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-get-temporal.plaintime.prototype.nanosecond
+description: Throw a TypeError if the receiver is invalid
+features: [Symbol, Temporal]
+---*/
+
+const nanosecond = Object.getOwnPropertyDescriptor(Temporal.PlainTime.prototype, "nanosecond").get;
+
+assert.sameValue(typeof nanosecond, "function");
+
+assert.throws(TypeError, () => nanosecond.call(undefined), "undefined");
+assert.throws(TypeError, () => nanosecond.call(null), "null");
+assert.throws(TypeError, () => nanosecond.call(true), "true");
+assert.throws(TypeError, () => nanosecond.call(""), "empty string");
+assert.throws(TypeError, () => nanosecond.call(Symbol()), "symbol");
+assert.throws(TypeError, () => nanosecond.call(1), "1");
+assert.throws(TypeError, () => nanosecond.call({}), "plain object");
+assert.throws(TypeError, () => nanosecond.call(Temporal.PlainTime), "Temporal.PlainTime");
+assert.throws(TypeError, () => nanosecond.call(Temporal.PlainTime.prototype), "Temporal.PlainTime.prototype");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/nanosecond/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/nanosecond/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/nanosecond/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/nanosecond/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/nanosecond/prop-desc.js
new file mode 100644
index 0000000000..21c0e2d3ce
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/nanosecond/prop-desc.js
@@ -0,0 +1,17 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-get-temporal.plaintime.prototype.nanosecond
+description: The "nanosecond" property of Temporal.PlainTime.prototype
+features: [Temporal]
+---*/
+
+const descriptor = Object.getOwnPropertyDescriptor(Temporal.PlainTime.prototype, "nanosecond");
+assert.sameValue(typeof descriptor.get, "function");
+assert.sameValue(descriptor.set, undefined);
+assert.sameValue(descriptor.enumerable, false);
+assert.sameValue(descriptor.configurable, true);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/nanosecond/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/nanosecond/shell.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/nanosecond/shell.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/prop-desc.js
new file mode 100644
index 0000000000..84b34b2961
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/prop-desc.js
@@ -0,0 +1,21 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal-plaintime-prototype
+description: The "prototype" property of Temporal.PlainTime
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+assert.sameValue(typeof Temporal.PlainTime.prototype, "object");
+assert.notSameValue(Temporal.PlainTime.prototype, null);
+
+verifyProperty(Temporal.PlainTime, "prototype", {
+  writable: false,
+  enumerable: false,
+  configurable: false,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/branding.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/branding.js
new file mode 100644
index 0000000000..7a1ab5e646
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/branding.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Throw a TypeError if the receiver is invalid
+features: [Symbol, Temporal]
+---*/
+
+const round = Temporal.PlainTime.prototype.round;
+
+assert.sameValue(typeof round, "function");
+
+const args = ["hour"];
+
+assert.throws(TypeError, () => round.apply(undefined, args), "undefined");
+assert.throws(TypeError, () => round.apply(null, args), "null");
+assert.throws(TypeError, () => round.apply(true, args), "true");
+assert.throws(TypeError, () => round.apply("", args), "empty string");
+assert.throws(TypeError, () => round.apply(Symbol(), args), "symbol");
+assert.throws(TypeError, () => round.apply(1, args), "1");
+assert.throws(TypeError, () => round.apply({}, args), "plain object");
+assert.throws(TypeError, () => round.apply(Temporal.PlainTime, args), "Temporal.PlainTime");
+assert.throws(TypeError, () => round.apply(Temporal.PlainTime.prototype, args), "Temporal.PlainTime.prototype");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/builtin.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/builtin.js
new file mode 100644
index 0000000000..7535a67544
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/builtin.js
@@ -0,0 +1,36 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: >
+    Tests that Temporal.PlainTime.prototype.round
+    meets the requirements for built-in objects defined by the
+    introduction of chapter 17 of the ECMAScript Language Specification.
+info: |
+    Built-in functions that are not constructors do not have a "prototype" property unless
+    otherwise specified in the description of a particular function.
+
+    Unless specified otherwise, a built-in object that is callable as a function is a built-in
+    function object with the characteristics described in 10.3. Unless specified otherwise, the
+    [[Extensible]] internal slot of a built-in object initially has the value true.
+
+    Unless otherwise specified every built-in function and every built-in constructor has the
+    Function prototype object [...] as the value of its [[Prototype]] internal slot.
+features: [Temporal]
+---*/
+
+assert.sameValue(Object.isExtensible(Temporal.PlainTime.prototype.round),
+  true, "Built-in objects must be extensible.");
+
+assert.sameValue(Object.prototype.toString.call(Temporal.PlainTime.prototype.round),
+  "[object Function]", "Object.prototype.toString");
+
+assert.sameValue(Object.getPrototypeOf(Temporal.PlainTime.prototype.round),
+  Function.prototype, "prototype");
+
+assert.sameValue(Temporal.PlainTime.prototype.round.hasOwnProperty("prototype"),
+  false, "prototype property");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/length.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/length.js
new file mode 100644
index 0000000000..9d70c1585e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/length.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Temporal.PlainTime.prototype.round.length is 1
+info: |
+    Every built-in function object, including constructors, has a "length" property whose value is
+    an integer. Unless otherwise specified, this value is equal to the largest number of named
+    arguments shown in the subclause headings for the function description. Optional parameters
+    (which are indicated with brackets: [ ]) or rest parameters (which are shown using the form
+    «...name») are not included in the default argument count.
+
+    Unless otherwise specified, the "length" property of a built-in function object has the
+    attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.round, "length", {
+  value: 1,
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/name.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/name.js
new file mode 100644
index 0000000000..005ddfb2d8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/name.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Temporal.PlainTime.prototype.round.name is "round".
+info: |
+    Every built-in function object, including constructors, that is not identified as an anonymous
+    function has a "name" property whose value is a String. Unless otherwise specified, this value
+    is the name that is given to the function in this specification.
+
+    Unless otherwise specified, the "name" property of a built-in function object, if it exists,
+    has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.round, "name", {
+  value: "round",
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/not-a-constructor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/not-a-constructor.js
new file mode 100644
index 0000000000..bae3bd7f4c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/not-a-constructor.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: >
+  Temporal.PlainTime.prototype.round does not implement [[Construct]], is not new-able
+info: |
+    Built-in function objects that are not identified as constructors do not implement the
+    [[Construct]] internal method unless otherwise specified in the description of a particular
+    function.
+includes: [isConstructor.js]
+features: [Reflect.construct, Temporal]
+---*/
+
+assert.throws(TypeError, () => {
+  new Temporal.PlainTime.prototype.round();
+}, "Calling as constructor");
+
+assert.sameValue(isConstructor(Temporal.PlainTime.prototype.round), false,
+  "isConstructor(Temporal.PlainTime.prototype.round)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/options-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/options-wrong-type.js
new file mode 100644
index 0000000000..0a76a4e438
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/options-wrong-type.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: TypeError thrown when options argument is missing or a non-string primitive
+features: [BigInt, Symbol, Temporal]
+---*/
+
+const badOptions = [
+  undefined,
+  null,
+  true,
+  Symbol(),
+  1,
+  2n,
+];
+
+const instance = new Temporal.PlainTime();
+assert.throws(TypeError, () => instance.round(), "TypeError on missing options argument");
+for (const value of badOptions) {
+  assert.throws(TypeError, () => instance.round(value),
+    `TypeError on wrong options type ${typeof value}`);
+};
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/prop-desc.js
new file mode 100644
index 0000000000..72a70b43fd
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/prop-desc.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: The "round" property of Temporal.PlainTime.prototype
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+assert.sameValue(
+  typeof Temporal.PlainTime.prototype.round,
+  "function",
+  "`typeof PlainTime.prototype.round` is `function`"
+);
+
+verifyProperty(Temporal.PlainTime.prototype, "round", {
+  writable: true,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/rounding-cross-midnight.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/rounding-cross-midnight.js
new file mode 100644
index 0000000000..e21c60a69e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/rounding-cross-midnight.js
@@ -0,0 +1,17 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Rounding can cross midnight
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const plainTime = Temporal.PlainTime.from("23:59:59.999999999");
+for (const smallestUnit of ["hour", "minute", "second", "millisecond", "microsecond"]) {
+  TemporalHelpers.assertPlainTime(plainTime.round({ smallestUnit }), 0, 0, 0, 0, 0, 0);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-hours.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-hours.js
new file mode 100644
index 0000000000..9c995aeb2f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-hours.js
@@ -0,0 +1,36 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Valid values for roundingIncrement option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const plainTime = new Temporal.PlainTime(3, 34, 56, 987, 654, 321);
+
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "hours", roundingIncrement: 1 }),
+  4, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "hours", roundingIncrement: 2 }),
+  4, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "hours", roundingIncrement: 3 }),
+  3, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "hours", roundingIncrement: 4 }),
+  4, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "hours", roundingIncrement: 6 }),
+  6, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "hours", roundingIncrement: 8 }),
+  0, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "hours", roundingIncrement: 12 }),
+  0, 0, 0, 0, 0, 0, "hours");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-invalid.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-invalid.js
new file mode 100644
index 0000000000..3ee77213ab
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-invalid.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Tests roundingIncrement restrictions.
+features: [Temporal]
+---*/
+
+const plainTime = Temporal.PlainTime.from("08:22:36.123456789");
+
+assert.throws(RangeError, () => plainTime.round({ smallestUnit: "hours", roundingIncrement: 11 }));
+assert.throws(RangeError, () => plainTime.round({ smallestUnit: "minutes", roundingIncrement: 29 }));
+assert.throws(RangeError, () => plainTime.round({ smallestUnit: "seconds", roundingIncrement: 29 }));
+assert.throws(RangeError, () => plainTime.round({ smallestUnit: "milliseconds", roundingIncrement: 29 }));
+assert.throws(RangeError, () => plainTime.round({ smallestUnit: "microseconds", roundingIncrement: 29 }));
+assert.throws(RangeError, () => plainTime.round({ smallestUnit: "nanoseconds", roundingIncrement: 29 }));
+assert.throws(RangeError, () => plainTime.round({ smallestUnit: "hours", roundingIncrement: 24 }));
+assert.throws(RangeError, () => plainTime.round({ smallestUnit: "minutes", roundingIncrement: 60 }));
+assert.throws(RangeError, () => plainTime.round({ smallestUnit: "seconds", roundingIncrement: 60 }));
+assert.throws(RangeError, () => plainTime.round({ smallestUnit: "milliseconds", roundingIncrement: 1000 }));
+assert.throws(RangeError, () => plainTime.round({ smallestUnit: "microseconds", roundingIncrement: 1000 }));
+assert.throws(RangeError, () => plainTime.round({ smallestUnit: "nanoseconds", roundingIncrement: 1000 }));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-microseconds.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-microseconds.js
new file mode 100644
index 0000000000..18ff82caee
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-microseconds.js
@@ -0,0 +1,60 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Valid values for roundingIncrement option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const plainTime = new Temporal.PlainTime(3, 34, 56, 987, 654, 321);
+
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "microseconds", roundingIncrement: 1 }),
+  3, 34, 56, 987, 654, 0, "microseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "microseconds", roundingIncrement: 2 }),
+  3, 34, 56, 987, 654, 0, "microseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "microseconds", roundingIncrement: 4 }),
+  3, 34, 56, 987, 656, 0, "microseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "microseconds", roundingIncrement: 5 }),
+  3, 34, 56, 987, 655, 0, "microseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "microseconds", roundingIncrement: 8 }),
+  3, 34, 56, 987, 656, 0, "microseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "microseconds", roundingIncrement: 10 }),
+  3, 34, 56, 987, 650, 0, "microseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "microseconds", roundingIncrement: 20 }),
+  3, 34, 56, 987, 660, 0, "microseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "microseconds", roundingIncrement: 25 }),
+  3, 34, 56, 987, 650, 0, "microseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "microseconds", roundingIncrement: 40 }),
+  3, 34, 56, 987, 640, 0, "microseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "microseconds", roundingIncrement: 50 }),
+  3, 34, 56, 987, 650, 0, "microseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "microseconds", roundingIncrement: 100 }),
+  3, 34, 56, 987, 700, 0, "microseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "microseconds", roundingIncrement: 125 }),
+  3, 34, 56, 987, 625, 0, "microseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "microseconds", roundingIncrement: 200 }),
+  3, 34, 56, 987, 600, 0, "microseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "microseconds", roundingIncrement: 250 }),
+  3, 34, 56, 987, 750, 0, "microseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "microseconds", roundingIncrement: 500 }),
+  3, 34, 56, 987, 500, 0, "microseconds");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-milliseconds.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-milliseconds.js
new file mode 100644
index 0000000000..e28334d9cc
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-milliseconds.js
@@ -0,0 +1,60 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Valid values for roundingIncrement option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const plainTime = new Temporal.PlainTime(3, 34, 56, 987, 654, 321);
+
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "milliseconds", roundingIncrement: 1 }),
+  3, 34, 56, 988, 0, 0, "milliseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "milliseconds", roundingIncrement: 2 }),
+  3, 34, 56, 988, 0, 0, "milliseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "milliseconds", roundingIncrement: 4 }),
+  3, 34, 56, 988, 0, 0, "milliseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "milliseconds", roundingIncrement: 5 }),
+  3, 34, 56, 990, 0, 0, "milliseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "milliseconds", roundingIncrement: 8 }),
+  3, 34, 56, 984, 0, 0, "milliseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "milliseconds", roundingIncrement: 10 }),
+  3, 34, 56, 990, 0, 0, "milliseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "milliseconds", roundingIncrement: 20 }),
+  3, 34, 56, 980, 0, 0, "milliseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "milliseconds", roundingIncrement: 25 }),
+  3, 34, 57, 0, 0, 0, "milliseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "milliseconds", roundingIncrement: 40 }),
+  3, 34, 57, 0, 0, 0, "milliseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "milliseconds", roundingIncrement: 50 }),
+  3, 34, 57, 0, 0, 0, "milliseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "milliseconds", roundingIncrement: 100 }),
+  3, 34, 57, 0, 0, 0, "milliseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "milliseconds", roundingIncrement: 125 }),
+  3, 34, 57, 0, 0, 0, "milliseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "milliseconds", roundingIncrement: 200 }),
+  3, 34, 57, 0, 0, 0, "milliseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "milliseconds", roundingIncrement: 250 }),
+  3, 34, 57, 0, 0, 0, "milliseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "milliseconds", roundingIncrement: 500 }),
+  3, 34, 57, 0, 0, 0, "milliseconds");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-minutes.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-minutes.js
new file mode 100644
index 0000000000..87cf21a294
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-minutes.js
@@ -0,0 +1,48 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Valid values for roundingIncrement option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const plainTime = new Temporal.PlainTime(3, 34, 56, 987, 654, 321);
+
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "minutes", roundingIncrement: 1 }),
+  3, 35, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "minutes", roundingIncrement: 2 }),
+  3, 34, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "minutes", roundingIncrement: 3 }),
+  3, 36, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "minutes", roundingIncrement: 4 }),
+  3, 36, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "minutes", roundingIncrement: 5 }),
+  3, 35, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "minutes", roundingIncrement: 6 }),
+  3, 36, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "minutes", roundingIncrement: 10 }),
+  3, 30, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "minutes", roundingIncrement: 12 }),
+  3, 36, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "minutes", roundingIncrement: 15 }),
+  3, 30, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "minutes", roundingIncrement: 20 }),
+  3, 40, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "minutes", roundingIncrement: 30 }),
+  3, 30, 0, 0, 0, 0, "minutes");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-nan.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-nan.js
new file mode 100644
index 0000000000..3272f5d3f9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-nan.js
@@ -0,0 +1,21 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: RangeError thrown when roundingIncrement option is NaN
+info: |
+    sec-getoption step 8.b:
+      b. If _value_ is *NaN*, throw a *RangeError* exception.
+    sec-temporal-totemporalroundingincrement step 5:
+      5. Let _increment_ be ? GetOption(_normalizedOptions_, *"roundingIncrement"*, « Number », *undefined*, 1).
+    sec-temporal.plaintime.prototype.round step 11:
+      10. Let _roundingIncrement_ be ? ToTemporalRoundingIncrement(_options_, _maximum_, *false*).
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+assert.throws(RangeError, () => time.round({ smallestUnit: 'second', roundingIncrement: NaN }));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-nanoseconds.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-nanoseconds.js
new file mode 100644
index 0000000000..00d09e5062
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-nanoseconds.js
@@ -0,0 +1,60 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Valid values for roundingIncrement option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const plainTime = new Temporal.PlainTime(3, 34, 56, 987, 654, 321);
+
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "nanoseconds", roundingIncrement: 1 }),
+  3, 34, 56, 987, 654, 321, "nanoseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "nanoseconds", roundingIncrement: 2 }),
+  3, 34, 56, 987, 654, 322, "nanoseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "nanoseconds", roundingIncrement: 4 }),
+  3, 34, 56, 987, 654, 320, "nanoseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "nanoseconds", roundingIncrement: 5 }),
+  3, 34, 56, 987, 654, 320, "nanoseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "nanoseconds", roundingIncrement: 8 }),
+  3, 34, 56, 987, 654, 320, "nanoseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "nanoseconds", roundingIncrement: 10 }),
+  3, 34, 56, 987, 654, 320, "nanoseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "nanoseconds", roundingIncrement: 20 }),
+  3, 34, 56, 987, 654, 320, "nanoseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "nanoseconds", roundingIncrement: 25 }),
+  3, 34, 56, 987, 654, 325, "nanoseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "nanoseconds", roundingIncrement: 40 }),
+  3, 34, 56, 987, 654, 320, "nanoseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "nanoseconds", roundingIncrement: 50 }),
+  3, 34, 56, 987, 654, 300, "nanoseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "nanoseconds", roundingIncrement: 100 }),
+  3, 34, 56, 987, 654, 300, "nanoseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "nanoseconds", roundingIncrement: 125 }),
+  3, 34, 56, 987, 654, 375, "nanoseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "nanoseconds", roundingIncrement: 200 }),
+  3, 34, 56, 987, 654, 400, "nanoseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "nanoseconds", roundingIncrement: 250 }),
+  3, 34, 56, 987, 654, 250, "nanoseconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "nanoseconds", roundingIncrement: 500 }),
+  3, 34, 56, 987, 654, 500, "nanoseconds");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-non-integer.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-non-integer.js
new file mode 100644
index 0000000000..b523e97cdd
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-non-integer.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Rounding for roundingIncrement option
+info: |
+    ToTemporalRoundingIncrement ( _normalizedOptions_ )
+
+    1. Let _increment_ be ? GetOption(_normalizedOptions_, *"roundingIncrement"*, *"number"*, *undefined*, *1*<sub>𝔽</sub>).
+    2. If _increment_ is not finite, throw a *RangeError* exception.
+    3. Let _integerIncrement_ be truncate(ℝ(_increment_)).
+    4. If _integerIncrement_ < 1 or _integerIncrement_ > 10<sup>9</sup>, throw a *RangeError* exception.
+    5. Return _integerIncrement_.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 0, 0, 5);
+const result = time.round({ smallestUnit: "nanosecond", roundingIncrement: 2.5, roundingMode: "expand" });
+TemporalHelpers.assertPlainTime(result, 12, 34, 56, 0, 0, 6, "roundingIncrement 2.5 truncates to 2");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-out-of-range.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-out-of-range.js
new file mode 100644
index 0000000000..6214294593
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-out-of-range.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: RangeError thrown when roundingIncrement option out of range
+info: |
+    ToTemporalRoundingIncrement ( _normalizedOptions_ )
+
+    1. Let _increment_ be ? GetOption(_normalizedOptions_, *"roundingIncrement"*, *"number"*, *undefined*, *1*<sub>𝔽</sub>).
+    2. If _increment_ is not finite, throw a *RangeError* exception.
+    3. Let _integerIncrement_ be truncate(ℝ(_increment_)).
+    4. If _integerIncrement_ < 1 or _integerIncrement_ > 10<sup>9</sup>, throw a *RangeError* exception.
+    5. Return _integerIncrement_.
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 0, 0, 5);
+assert.throws(RangeError, () => time.round({ smallestUnit: "nanoseconds", roundingIncrement: -Infinity }));
+assert.throws(RangeError, () => time.round({ smallestUnit: "nanoseconds", roundingIncrement: -1 }));
+assert.throws(RangeError, () => time.round({ smallestUnit: "nanoseconds", roundingIncrement: 0 }));
+assert.throws(RangeError, () => time.round({ smallestUnit: "nanoseconds", roundingIncrement: 0.9 }));
+assert.throws(RangeError, () => time.round({ smallestUnit: "nanoseconds", roundingIncrement: 1e9 + 1 }));
+assert.throws(RangeError, () => time.round({ smallestUnit: "nanoseconds", roundingIncrement: Infinity }));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-seconds.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-seconds.js
new file mode 100644
index 0000000000..120806bb3e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-seconds.js
@@ -0,0 +1,48 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Valid values for roundingIncrement option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const plainTime = new Temporal.PlainTime(3, 34, 56, 987, 654, 321);
+
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "seconds", roundingIncrement: 1 }),
+  3, 34, 57, 0, 0, 0, "seconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "seconds", roundingIncrement: 2 }),
+  3, 34, 56, 0, 0, 0, "seconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "seconds", roundingIncrement: 3 }),
+  3, 34, 57, 0, 0, 0, "seconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "seconds", roundingIncrement: 4 }),
+  3, 34, 56, 0, 0, 0, "seconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "seconds", roundingIncrement: 5 }),
+  3, 34, 55, 0, 0, 0, "seconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "seconds", roundingIncrement: 6 }),
+  3, 34, 54, 0, 0, 0, "seconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "seconds", roundingIncrement: 10 }),
+  3, 35, 0, 0, 0, 0, "seconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "seconds", roundingIncrement: 12 }),
+  3, 35, 0, 0, 0, 0, "seconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "seconds", roundingIncrement: 15 }),
+  3, 35, 0, 0, 0, 0, "seconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "seconds", roundingIncrement: 20 }),
+  3, 35, 0, 0, 0, 0, "seconds");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "seconds", roundingIncrement: 30 }),
+  3, 35, 0, 0, 0, 0, "seconds");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-undefined.js
new file mode 100644
index 0000000000..071d677df3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-undefined.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Fallback value for roundingIncrement option
+info: |
+    sec-getoption step 3:
+      3. If _value_ is *undefined*, return _fallback_.
+    sec-temporal-totemporalroundingincrement step 5:
+      5. Let _increment_ be ? GetOption(_normalizedOptions_, *"roundingIncrement"*, « Number », *undefined*, 1).
+    sec-temporal.plaintime.prototype.round step 11:
+      11. Let _roundingIncrement_ be ? ToTemporalRoundingIncrement(_options_, _maximum_, *false*).
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const explicit = time.round({ smallestUnit: 'second', roundingIncrement: undefined });
+TemporalHelpers.assertPlainTime(explicit, 12, 34, 57, 0, 0, 0, "default roundingIncrement is 1");
+
+const implicit = time.round({ smallestUnit: 'second' });
+TemporalHelpers.assertPlainTime(implicit, 12, 34, 57, 0, 0, 0, "default roundingIncrement is 1");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-wrong-type.js
new file mode 100644
index 0000000000..c6466af90e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingincrement-wrong-type.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Type conversions for roundingIncrement option
+info: |
+    sec-getoption step 8.a:
+      a. Set _value_ to ? ToNumber(value).
+    sec-temporal-totemporalroundingincrement step 5:
+      5. Let _increment_ be ? GetOption(_normalizedOptions_, *"roundingIncrement"*, « Number », *undefined*, 1).
+    sec-temporal.plaintime.prototype.round step 11:
+      11. Let _roundingIncrement_ be ? ToTemporalRoundingIncrement(_options_, _maximum_, *false*).
+includes: [temporalHelpers.js, compareArray.js]
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+TemporalHelpers.checkRoundingIncrementOptionWrongType(
+  (roundingIncrement) => time.round({ smallestUnit: 'second', roundingIncrement }),
+  (result, descr) => TemporalHelpers.assertPlainTime(result, 12, 34, 57, 0, 0, 0, descr),
+  (result, descr) => TemporalHelpers.assertPlainTime(result, 12, 34, 56, 0, 0, 0, descr),
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-ceil.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-ceil.js
new file mode 100644
index 0000000000..d5018a893e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-ceil.js
@@ -0,0 +1,34 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Tests calculations with roundingMode "ceil".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(13, 46, 23, 123, 987, 500);
+
+const expected = [
+  ["hour", [14]],
+  ["minute", [13, 47]],
+  ["second", [13, 46, 24]],
+  ["millisecond", [13, 46, 23, 124]],
+  ["microsecond", [13, 46, 23, 123, 988]],
+  ["nanosecond", [13, 46, 23, 123, 987, 500]],
+];
+
+const roundingMode = "ceil";
+
+expected.forEach(([smallestUnit, expected]) => {
+  const [h, min = 0, s = 0, ms = 0, µs = 0, ns = 0] = expected;
+  TemporalHelpers.assertPlainTime(
+    instance.round({ smallestUnit, roundingMode }),
+    h, min, s, ms, µs, ns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-expand.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-expand.js
new file mode 100644
index 0000000000..d7b32ea932
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-expand.js
@@ -0,0 +1,34 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Tests calculations with roundingMode "expand".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(13, 46, 23, 123, 987, 500);
+
+const expected = [
+  ["hour", [14]],
+  ["minute", [13, 47]],
+  ["second", [13, 46, 24]],
+  ["millisecond", [13, 46, 23, 124]],
+  ["microsecond", [13, 46, 23, 123, 988]],
+  ["nanosecond", [13, 46, 23, 123, 987, 500]],
+];
+
+const roundingMode = "expand";
+
+expected.forEach(([smallestUnit, expected]) => {
+  const [h, min = 0, s = 0, ms = 0, µs = 0, ns = 0] = expected;
+  TemporalHelpers.assertPlainTime(
+    instance.round({ smallestUnit, roundingMode }),
+    h, min, s, ms, µs, ns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-floor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-floor.js
new file mode 100644
index 0000000000..2953b4857e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-floor.js
@@ -0,0 +1,34 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Tests calculations with roundingMode "floor".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(13, 46, 23, 123, 987, 500);
+
+const expected = [
+  ["hour", [13]],
+  ["minute", [13, 46]],
+  ["second", [13, 46, 23]],
+  ["millisecond", [13, 46, 23, 123]],
+  ["microsecond", [13, 46, 23, 123, 987]],
+  ["nanosecond", [13, 46, 23, 123, 987, 500]],
+];
+
+const roundingMode = "floor";
+
+expected.forEach(([smallestUnit, expected]) => {
+  const [h, min = 0, s = 0, ms = 0, µs = 0, ns = 0] = expected;
+  TemporalHelpers.assertPlainTime(
+    instance.round({ smallestUnit, roundingMode }),
+    h, min, s, ms, µs, ns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-halfCeil.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-halfCeil.js
new file mode 100644
index 0000000000..953dacdae8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-halfCeil.js
@@ -0,0 +1,34 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Tests calculations with roundingMode "halfCeil".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(13, 46, 23, 123, 987, 500);
+
+const expected = [
+  ["hour", [14]],
+  ["minute", [13, 46]],
+  ["second", [13, 46, 23]],
+  ["millisecond", [13, 46, 23, 124]],
+  ["microsecond", [13, 46, 23, 123, 988]],
+  ["nanosecond", [13, 46, 23, 123, 987, 500]],
+];
+
+const roundingMode = "halfCeil";
+
+expected.forEach(([smallestUnit, expected]) => {
+  const [h, min = 0, s = 0, ms = 0, µs = 0, ns = 0] = expected;
+  TemporalHelpers.assertPlainTime(
+    instance.round({ smallestUnit, roundingMode }),
+    h, min, s, ms, µs, ns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-halfEven.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-halfEven.js
new file mode 100644
index 0000000000..73d66da9f9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-halfEven.js
@@ -0,0 +1,34 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Tests calculations with roundingMode "halfEven".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(13, 46, 23, 123, 987, 500);
+
+const expected = [
+  ["hour", [14]],
+  ["minute", [13, 46]],
+  ["second", [13, 46, 23]],
+  ["millisecond", [13, 46, 23, 124]],
+  ["microsecond", [13, 46, 23, 123, 988]],
+  ["nanosecond", [13, 46, 23, 123, 987, 500]],
+];
+
+const roundingMode = "halfEven";
+
+expected.forEach(([smallestUnit, expected]) => {
+  const [h, min = 0, s = 0, ms = 0, µs = 0, ns = 0] = expected;
+  TemporalHelpers.assertPlainTime(
+    instance.round({ smallestUnit, roundingMode }),
+    h, min, s, ms, µs, ns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-halfExpand.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-halfExpand.js
new file mode 100644
index 0000000000..3226b024f1
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-halfExpand.js
@@ -0,0 +1,34 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Tests calculations with roundingMode "halfExpand".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(13, 46, 23, 123, 987, 500);
+
+const expected = [
+  ["hour", [14]],
+  ["minute", [13, 46]],
+  ["second", [13, 46, 23]],
+  ["millisecond", [13, 46, 23, 124]],
+  ["microsecond", [13, 46, 23, 123, 988]],
+  ["nanosecond", [13, 46, 23, 123, 987, 500]],
+];
+
+const roundingMode = "halfExpand";
+
+expected.forEach(([smallestUnit, expected]) => {
+  const [h, min = 0, s = 0, ms = 0, µs = 0, ns = 0] = expected;
+  TemporalHelpers.assertPlainTime(
+    instance.round({ smallestUnit, roundingMode }),
+    h, min, s, ms, µs, ns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-halfFloor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-halfFloor.js
new file mode 100644
index 0000000000..c3ef77be4c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-halfFloor.js
@@ -0,0 +1,34 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Tests calculations with roundingMode "halfFloor".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(13, 46, 23, 123, 987, 500);
+
+const expected = [
+  ["hour", [14]],
+  ["minute", [13, 46]],
+  ["second", [13, 46, 23]],
+  ["millisecond", [13, 46, 23, 124]],
+  ["microsecond", [13, 46, 23, 123, 987]],
+  ["nanosecond", [13, 46, 23, 123, 987, 500]],
+];
+
+const roundingMode = "halfFloor";
+
+expected.forEach(([smallestUnit, expected]) => {
+  const [h, min = 0, s = 0, ms = 0, µs = 0, ns = 0] = expected;
+  TemporalHelpers.assertPlainTime(
+    instance.round({ smallestUnit, roundingMode }),
+    h, min, s, ms, µs, ns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-halfTrunc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-halfTrunc.js
new file mode 100644
index 0000000000..0049978794
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-halfTrunc.js
@@ -0,0 +1,34 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Tests calculations with roundingMode "halfTrunc".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(13, 46, 23, 123, 987, 500);
+
+const expected = [
+  ["hour", [14]],
+  ["minute", [13, 46]],
+  ["second", [13, 46, 23]],
+  ["millisecond", [13, 46, 23, 124]],
+  ["microsecond", [13, 46, 23, 123, 987]],
+  ["nanosecond", [13, 46, 23, 123, 987, 500]],
+];
+
+const roundingMode = "halfTrunc";
+
+expected.forEach(([smallestUnit, expected]) => {
+  const [h, min = 0, s = 0, ms = 0, µs = 0, ns = 0] = expected;
+  TemporalHelpers.assertPlainTime(
+    instance.round({ smallestUnit, roundingMode }),
+    h, min, s, ms, µs, ns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-invalid-string.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-invalid-string.js
new file mode 100644
index 0000000000..c946c3d7b1
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-invalid-string.js
@@ -0,0 +1,16 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: RangeError thrown when roundingMode option not one of the allowed string values
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 123, 987, 500);
+for (const roundingMode of ["other string", "cile", "CEIL", "ce\u0131l", "auto", "halfexpand", "floor\0"]) {
+  assert.throws(RangeError, () => time.round({ smallestUnit: "microsecond", roundingMode }));
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-trunc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-trunc.js
new file mode 100644
index 0000000000..91348dac2a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-trunc.js
@@ -0,0 +1,34 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Tests calculations with roundingMode "trunc".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(13, 46, 23, 123, 987, 500);
+
+const expected = [
+  ["hour", [13]],
+  ["minute", [13, 46]],
+  ["second", [13, 46, 23]],
+  ["millisecond", [13, 46, 23, 123]],
+  ["microsecond", [13, 46, 23, 123, 987]],
+  ["nanosecond", [13, 46, 23, 123, 987, 500]],
+];
+
+const roundingMode = "trunc";
+
+expected.forEach(([smallestUnit, expected]) => {
+  const [h, min = 0, s = 0, ms = 0, µs = 0, ns = 0] = expected;
+  TemporalHelpers.assertPlainTime(
+    instance.round({ smallestUnit, roundingMode }),
+    h, min, s, ms, µs, ns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-undefined.js
new file mode 100644
index 0000000000..8ec1da0fd6
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-undefined.js
@@ -0,0 +1,56 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Tests calculations with roundingMode undefined.
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const plainTime = Temporal.PlainTime.from("13:46:23.123456789");
+
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "hour", roundingMode: undefined }),
+  14, 0, 0, 0, 0, 0, "hour");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "hour" }),
+  14, 0, 0, 0, 0, 0, "hour");
+
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "minute", roundingMode: undefined }),
+  13, 46, 0, 0, 0, 0, "minute");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "minute" }),
+  13, 46, 0, 0, 0, 0, "minute");
+
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "second", roundingMode: undefined }),
+  13, 46, 23, 0, 0, 0, "second");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "second" }),
+  13, 46, 23, 0, 0, 0, "second");
+
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "millisecond", roundingMode: undefined }),
+  13, 46, 23, 123, 0, 0, "millisecond");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "millisecond" }),
+  13, 46, 23, 123, 0, 0, "millisecond");
+
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "microsecond", roundingMode: undefined }),
+  13, 46, 23, 123, 457, 0, "microsecond");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "microsecond" }),
+  13, 46, 23, 123, 457, 0, "microsecond");
+
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "nanosecond", roundingMode: undefined }),
+  13, 46, 23, 123, 456, 789, "nanosecond");
+TemporalHelpers.assertPlainTime(
+  plainTime.round({ smallestUnit: "nanosecond" }),
+  13, 46, 23, 123, 456, 789, "nanosecond");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-wrong-type.js
new file mode 100644
index 0000000000..8d5bdb93c7
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundingmode-wrong-type.js
@@ -0,0 +1,18 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Type conversions for roundingMode option
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 123, 987, 500);
+TemporalHelpers.checkStringOptionWrongType("roundingMode", "halfExpand",
+  (roundingMode) => time.round({ smallestUnit: "microsecond", roundingMode }),
+  (result, descr) => TemporalHelpers.assertPlainTime(result, 12, 34, 56, 123, 988, 0, descr),
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundto-invalid-string.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundto-invalid-string.js
new file mode 100644
index 0000000000..b83be42070
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/roundto-invalid-string.js
@@ -0,0 +1,38 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: RangeError thrown when smallestUnit option not one of the allowed string values
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 123, 987, 500);
+const badValues = [
+  "era",
+  "eraYear",
+  "year",
+  "month",
+  "week",
+  "day",
+  "millisecond\0",
+  "mill\u0131second",
+  "SECOND",
+  "eras",
+  "eraYears",
+  "years",
+  "months",
+  "weeks",
+  "days",
+  "milliseconds\0",
+  "mill\u0131seconds",
+  "SECONDS",
+  "other string",
+];
+for (const smallestUnit of badValues) {
+  assert.throws(RangeError, () => time.round(smallestUnit),
+    `"${smallestUnit}" is not a valid value for smallest unit`);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/smallestunit-invalid-string.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/smallestunit-invalid-string.js
new file mode 100644
index 0000000000..58d452b3b4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/smallestunit-invalid-string.js
@@ -0,0 +1,38 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: RangeError thrown when smallestUnit option not one of the allowed string values
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 123, 987, 500);
+const badValues = [
+  "era",
+  "eraYear",
+  "year",
+  "month",
+  "week",
+  "day",
+  "millisecond\0",
+  "mill\u0131second",
+  "SECOND",
+  "eras",
+  "eraYears",
+  "years",
+  "months",
+  "weeks",
+  "days",
+  "milliseconds\0",
+  "mill\u0131seconds",
+  "SECONDS",
+  "other string",
+];
+for (const smallestUnit of badValues) {
+  assert.throws(RangeError, () => time.round({ smallestUnit }),
+    `"${smallestUnit}" is not a valid value for smallest unit`);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/smallestunit-missing.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/smallestunit-missing.js
new file mode 100644
index 0000000000..389f5d99d3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/smallestunit-missing.js
@@ -0,0 +1,16 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: RangeError thrown when smallestUnit option is missing
+features: [Temporal]
+---*/
+
+const plainTime = new Temporal.PlainTime(12, 34, 56, 123, 987, 500);
+assert.throws(TypeError, () => plainTime.round());
+assert.throws(RangeError, () => plainTime.round({}));
+assert.throws(RangeError, () => plainTime.round({ roundingIncrement: 1, roundingMode: "ceil" }));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/smallestunit-plurals-accepted.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/smallestunit-plurals-accepted.js
new file mode 100644
index 0000000000..524ce45ca5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/smallestunit-plurals-accepted.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Plural units are accepted as well for the smallestUnit option
+includes: [temporalHelpers.js]
+features: [Temporal, arrow-function]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 789, 999, 999);
+const validUnits = [
+  "hour",
+  "minute",
+  "second",
+  "millisecond",
+  "microsecond",
+  "nanosecond",
+];
+TemporalHelpers.checkPluralUnitsAccepted((smallestUnit) => time.round({ smallestUnit }), validUnits);
+TemporalHelpers.checkPluralUnitsAccepted((smallestUnit) => time.round(smallestUnit), validUnits);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/smallestunit-string-shorthand.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/smallestunit-string-shorthand.js
new file mode 100644
index 0000000000..803dab8933
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/smallestunit-string-shorthand.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: String as first argument is equivalent to options bag with smallestUnit option
+includes: [temporalHelpers.js]
+features: [Temporal, arrow-function]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 789, 999, 999);
+const validUnits = [
+  "hour",
+  "minute",
+  "second",
+  "millisecond",
+  "microsecond",
+  "nanosecond",
+];
+validUnits.forEach((smallestUnit) => {
+  const full = instance.round({ smallestUnit });
+  const shorthand = instance.round(smallestUnit);
+  TemporalHelpers.assertPlainTimesEqual(shorthand, full, `"${smallestUnit}" as first argument to round is equivalent to options bag`);
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/smallestunit-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/smallestunit-wrong-type.js
new file mode 100644
index 0000000000..0b68fac1fa
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/smallestunit-wrong-type.js
@@ -0,0 +1,18 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Type conversions for smallestUnit option
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 123, 987, 500);
+TemporalHelpers.checkStringOptionWrongType("smallestUnit", "microsecond",
+  (smallestUnit) => time.round({ smallestUnit }),
+  (result, descr) => TemporalHelpers.assertPlainTime(result, 12, 34, 56, 123, 988, 0, descr),
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/subclassing-ignored.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/subclassing-ignored.js
new file mode 100644
index 0000000000..b903a2b7c7
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/round/subclassing-ignored.js
@@ -0,0 +1,20 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.round
+description: Objects of a subclass are never created as return values.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+TemporalHelpers.checkSubclassingIgnored(
+  Temporal.PlainTime,
+  [12, 34, 56, 987, 654, 321],
+  "round",
+  [{ smallestUnit: 'second' }],
+  (result) => TemporalHelpers.assertPlainTime(result, 12, 34, 57, 0, 0, 0),
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/second/branding.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/second/branding.js
new file mode 100644
index 0000000000..d193985b85
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/second/branding.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-get-temporal.plaintime.prototype.second
+description: Throw a TypeError if the receiver is invalid
+features: [Symbol, Temporal]
+---*/
+
+const second = Object.getOwnPropertyDescriptor(Temporal.PlainTime.prototype, "second").get;
+
+assert.sameValue(typeof second, "function");
+
+assert.throws(TypeError, () => second.call(undefined), "undefined");
+assert.throws(TypeError, () => second.call(null), "null");
+assert.throws(TypeError, () => second.call(true), "true");
+assert.throws(TypeError, () => second.call(""), "empty string");
+assert.throws(TypeError, () => second.call(Symbol()), "symbol");
+assert.throws(TypeError, () => second.call(1), "1");
+assert.throws(TypeError, () => second.call({}), "plain object");
+assert.throws(TypeError, () => second.call(Temporal.PlainTime), "Temporal.PlainTime");
+assert.throws(TypeError, () => second.call(Temporal.PlainTime.prototype), "Temporal.PlainTime.prototype");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/second/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/second/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/second/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/second/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/second/prop-desc.js
new file mode 100644
index 0000000000..071c2436e4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/second/prop-desc.js
@@ -0,0 +1,17 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-get-temporal.plaintime.prototype.second
+description: The "second" property of Temporal.PlainTime.prototype
+features: [Temporal]
+---*/
+
+const descriptor = Object.getOwnPropertyDescriptor(Temporal.PlainTime.prototype, "second");
+assert.sameValue(typeof descriptor.get, "function");
+assert.sameValue(descriptor.set, undefined);
+assert.sameValue(descriptor.enumerable, false);
+assert.sameValue(descriptor.configurable, true);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/second/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/second/shell.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/second/shell.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/shell.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/shell.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-cast.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-cast.js
new file mode 100644
index 0000000000..7f851b1f70
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-cast.js
@@ -0,0 +1,21 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Casts the argument
+includes: [temporalHelpers.js]
+features: [Temporal, arrow-function]
+---*/
+
+const plainTime = new Temporal.PlainTime(15, 23, 30, 123, 456, 789);
+TemporalHelpers.assertDuration(plainTime.since("16:34"),
+  0, 0, 0, 0, /* hours = */ -1, /* minutes = */ -10, /* seconds = */ -29, -876, -543, -211, "string");
+TemporalHelpers.assertDuration(plainTime.since({ hour: 16, minute: 34 }),
+  0, 0, 0, 0, /* hours = */ -1, /* minutes = */ -10, /* seconds = */ -29, -876, -543, -211, "object");
+
+assert.throws(TypeError, () => plainTime.since({}), "empty");
+assert.throws(TypeError, () => plainTime.since({ minutes: 30 }), "only plural 'minutes'");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-number.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-number.js
new file mode 100644
index 0000000000..3889dfea59
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-number.js
@@ -0,0 +1,34 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: A number is converted to a string, then to Temporal.PlainTime
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const arg = 123456.987654321;
+
+const result = instance.since(arg);
+TemporalHelpers.assertDuration(result, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, "123456.987654321 is a valid ISO string for PlainTime");
+
+const numbers = [
+  1,
+  -123456.987654321,
+  1234567,
+  123456.9876543219,
+];
+
+for (const arg of numbers) {
+  assert.throws(
+    RangeError,
+    () => instance.since(arg),
+    `Number ${arg} does not convert to a valid ISO string for PlainTime`
+  );
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-calendar-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-calendar-annotation.js
new file mode 100644
index 0000000000..0110659c29
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-calendar-annotation.js
@@ -0,0 +1,41 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Various forms of calendar annotation; critical flag has no effect
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const tests = [
+  ["12:34:56.987654321[u-ca=iso8601]", "without time zone"],
+  ["12:34:56.987654321[UTC][u-ca=iso8601]", "with time zone"],
+  ["12:34:56.987654321[!u-ca=iso8601]", "with ! and no time zone"],
+  ["12:34:56.987654321[UTC][!u-ca=iso8601]", "with ! and time zone"],
+  ["T12:34:56.987654321[u-ca=iso8601]", "with T and no time zone"],
+  ["T12:34:56.987654321[UTC][u-ca=iso8601]", "with T and time zone"],
+  ["T12:34:56.987654321[!u-ca=iso8601]", "with T, !, and no time zone"],
+  ["T12:34:56.987654321[UTC][!u-ca=iso8601]", "with T, !, and time zone"],
+  ["1970-01-01T12:34:56.987654321[u-ca=iso8601]", "with date and no time zone"],
+  ["1970-01-01T12:34:56.987654321[UTC][u-ca=iso8601]", "with date and time zone"],
+  ["1970-01-01T12:34:56.987654321[!u-ca=iso8601]", "with !, date, and no time zone"],
+  ["1970-01-01T12:34:56.987654321[UTC][!u-ca=iso8601]", "with !, date, and time zone"],
+  ["1970-01-01T12:34:56.987654321[u-ca=iso8601][u-ca=discord]", "second annotation ignored"],
+  ["1970-01-01T12:34:56.987654321[u-ca=iso8601][!u-ca=discord]", "second annotation ignored even with !"],
+];
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+tests.forEach(([arg, description]) => {
+  const result = instance.since(arg);
+
+  TemporalHelpers.assertDuration(
+    result,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    `calendar annotation (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-critical-unknown-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-critical-unknown-annotation.js
new file mode 100644
index 0000000000..df33154711
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-critical-unknown-annotation.js
@@ -0,0 +1,29 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Unknown annotations with critical flag are rejected
+features: [Temporal]
+---*/
+
+const invalidStrings = [
+  "00:00[!foo=bar]",
+  "T00:00[!foo=bar]",
+  "1970-01-01T00:00[!foo=bar]",
+  "1970-01-01T00:00[UTC][!foo=bar]",
+  "1970-01-01T00:00[u-ca=iso8601][!foo=bar]",
+  "1970-01-01T00:00[UTC][!foo=bar][u-ca=iso8601]",
+  "1970-01-01T00:00[foo=bar][!_foo-bar0=Dont-Ignore-This-99999999999]",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => instance.since(arg),
+    `reject unknown annotation with critical flag: ${arg}`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-date-with-utc-offset.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-date-with-utc-offset.js
new file mode 100644
index 0000000000..515276c7a1
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-date-with-utc-offset.js
@@ -0,0 +1,53 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: UTC offset not valid with format that does not include a time
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const validStrings = [
+  "12:34:56.987654321+00:00",
+  "12:34:56.987654321+00:00[UTC]",
+  "12:34:56.987654321+00:00[!UTC]",
+  "12:34:56.987654321-02:30[America/St_Johns]",
+  "1976-11-18T12:34:56.987654321+00:00",
+  "1976-11-18T12:34:56.987654321+00:00[UTC]",
+  "1976-11-18T12:34:56.987654321+00:00[!UTC]",
+  "1976-11-18T12:34:56.987654321-02:30[America/St_Johns]",
+];
+
+for (const arg of validStrings) {
+  const result = instance.since(arg);
+
+  TemporalHelpers.assertDuration(
+    result,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    `"${arg}" is a valid UTC offset with time for PlainTime`
+  );
+}
+
+const invalidStrings = [
+  "2022-09-15Z",
+  "2022-09-15Z[UTC]",
+  "2022-09-15Z[Europe/Vienna]",
+  "2022-09-15+00:00",
+  "2022-09-15+00:00[UTC]",
+  "2022-09-15-02:30",
+  "2022-09-15-02:30[America/St_Johns]",
+];
+
+for (const arg of invalidStrings) {
+  assert.throws(
+    RangeError,
+    () => instance.since(arg),
+    `"${arg}" UTC offset without time is not valid for PlainTime`
+  );
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-multiple-time-zone.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-multiple-time-zone.js
new file mode 100644
index 0000000000..e4d36e109b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-multiple-time-zone.js
@@ -0,0 +1,29 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: More than one time zone annotation is not syntactical
+features: [Temporal]
+---*/
+
+const invalidStrings = [
+  "00:00[UTC][UTC]",
+  "T00:00[UTC][UTC]",
+  "1970-01-01T00:00[UTC][UTC]",
+  "1970-01-01T00:00[!UTC][UTC]",
+  "1970-01-01T00:00[UTC][!UTC]",
+  "1970-01-01T00:00[UTC][u-ca=iso8601][UTC]",
+  "1970-01-01T00:00[UTC][foo=bar][UTC]",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => instance.since(arg),
+    `reject more than one time zone annotation: ${arg}`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-no-implicit-midnight.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-no-implicit-midnight.js
new file mode 100644
index 0000000000..eb168cbd6b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-no-implicit-midnight.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: RangeError thrown if a date-only string is passed in a PlainTime context
+features: [Temporal, arrow-function]
+---*/
+
+const arg = "2019-10-01";
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+assert.throws(
+  RangeError,
+  () => instance.since(arg),
+  "Date-only string throws, does not implicitly convert to midnight"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-time-designator-required-for-disambiguation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-time-designator-required-for-disambiguation.js
new file mode 100644
index 0000000000..fa2fa94c0a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-time-designator-required-for-disambiguation.js
@@ -0,0 +1,37 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: ISO 8601 time designator "T" required in cases of ambiguity
+includes: [temporalHelpers.js]
+features: [Temporal, arrow-function]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+TemporalHelpers.ISO.plainTimeStringsAmbiguous().forEach((string) => {
+  let arg = string;
+  assert.throws(
+    RangeError,
+    () => instance.since(arg),
+    `'${arg}' is ambiguous and requires T prefix`
+  );
+  // The same string with a T prefix should not throw:
+  arg = `T${string}`;
+  instance.since(arg);
+
+  arg = ` ${string}`;
+  assert.throws(
+    RangeError,
+    () => instance.since(arg),
+    `space is not accepted as a substitute for T prefix: '${arg}'`
+  );
+});
+
+// None of these should throw without a T prefix, because they are unambiguously time strings:
+TemporalHelpers.ISO.plainTimeStringsUnambiguous().forEach(
+  (arg) => instance.since(arg));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-time-separators.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-time-separators.js
new file mode 100644
index 0000000000..9f8f39420d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-time-separators.js
@@ -0,0 +1,32 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Time separator in string argument can vary
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const tests = [
+  ["1976-11-18T12:34:56.987654321", "uppercase T"],
+  ["1976-11-18t12:34:56.987654321", "lowercase T"],
+  ["1976-11-18 12:34:56.987654321", "space between date and time"],
+  ["T12:34:56.987654321", "time-only uppercase T"],
+  ["t12:34:56.987654321", "time-only lowercase T"],
+];
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+tests.forEach(([arg, description]) => {
+  const result = instance.since(arg);
+
+  TemporalHelpers.assertDuration(
+    result,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    `variant time separators (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-time-zone-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-time-zone-annotation.js
new file mode 100644
index 0000000000..af73945042
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-time-zone-annotation.js
@@ -0,0 +1,51 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Various forms of time zone annotation; critical flag has no effect
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const tests = [
+  ["12:34:56.987654321[Asia/Kolkata]", "named, with no offset"],
+  ["12:34:56.987654321[!Europe/Vienna]", "named, with ! and no offset"],
+  ["12:34:56.987654321[+00:00]", "numeric, with no offset"],
+  ["12:34:56.987654321[!-02:30]", "numeric, with ! and no offset"],
+  ["T12:34:56.987654321[UTC]", "named, with T and no offset"],
+  ["T12:34:56.987654321[!Africa/Abidjan]", "named, with T, !, and no offset"],
+  ["T12:34:56.987654321[+01:00]", "numeric, with T and no offset"],
+  ["T12:34:56.987654321[!-08:00]", "numeric, with T, !, and no offset"],
+  ["12:34:56.987654321+00:00[America/Sao_Paulo]", "named, with offset"],
+  ["12:34:56.987654321+00:00[!Asia/Tokyo]", "named, with ! and offset"],
+  ["12:34:56.987654321+00:00[-02:30]", "numeric, with offset"],
+  ["12:34:56.987654321+00:00[!+00:00]", "numeric, with ! and offset"],
+  ["T12:34:56.987654321+00:00[America/New_York]", "named, with T and offset"],
+  ["T12:34:56.987654321+00:00[!UTC]", "named, with T, !, and offset"],
+  ["T12:34:56.987654321+00:00[-08:00]", "numeric, with T and offset"],
+  ["T12:34:56.987654321+00:00[!+01:00]", "numeric, with T, !, and offset"],
+  ["1970-01-01T12:34:56.987654321[Africa/Lagos]", "named, with date and no offset"],
+  ["1970-01-01T12:34:56.987654321[!America/Vancouver]", "named, with date, !, and no offset"],
+  ["1970-01-01T12:34:56.987654321[+00:00]", "numeric, with date and no offset"],
+  ["1970-01-01T12:34:56.987654321[!-02:30]", "numeric, with date, !, and no offset"],
+  ["1970-01-01T12:34:56.987654321+00:00[Europe/London]", "named, with date and offset"],
+  ["1970-01-01T12:34:56.987654321+00:00[!Asia/Seoul]", "named, with date, offset, and !"],
+  ["1970-01-01T12:34:56.987654321+00:00[+01:00]", "numeric, with date and offset"],
+  ["1970-01-01T12:34:56.987654321+00:00[!-08:00]", "numeric, with date, offset, and !"],
+];
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+tests.forEach(([arg, description]) => {
+  const result = instance.since(arg);
+
+  TemporalHelpers.assertDuration(
+    result,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    `time zone annotation (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-unknown-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-unknown-annotation.js
new file mode 100644
index 0000000000..3ff9323752
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-unknown-annotation.js
@@ -0,0 +1,40 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Various forms of unknown annotation
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const tests = [
+  ["12:34:56.987654321[foo=bar]", "alone"],
+  ["12:34:56.987654321[UTC][foo=bar]", "with time zone"],
+  ["12:34:56.987654321[u-ca=iso8601][foo=bar]", "with calendar"],
+  ["12:34:56.987654321[UTC][foo=bar][u-ca=iso8601]", "with time zone and calendar"],
+  ["T12:34:56.987654321[foo=bar]", "with T"],
+  ["T12:34:56.987654321[UTC][foo=bar]", "with T and time zone"],
+  ["T12:34:56.987654321[u-ca=iso8601][foo=bar]", "with T and calendar"],
+  ["T12:34:56.987654321[UTC][foo=bar][u-ca=iso8601]", "with T, time zone, and calendar"],
+  ["1970-01-01T12:34:56.987654321[foo=bar]", "with date"],
+  ["1970-01-01T12:34:56.987654321[UTC][foo=bar]", "with date and time zone"],
+  ["1970-01-01T12:34:56.987654321[u-ca=iso8601][foo=bar]", "with date and calendar"],
+  ["1970-01-01T12:34:56.987654321[UTC][foo=bar][u-ca=iso8601]", "with date, time zone, and calendar"],
+  ["1970-01-01T12:34:56.987654321[foo=bar][_foo-bar0=Ignore-This-999999999999]", "with another unknown annotation"],
+];
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+tests.forEach(([arg, description]) => {
+  const result = instance.since(arg);
+
+  TemporalHelpers.assertDuration(
+    result,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    `unknown annotation (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-with-time-designator.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-with-time-designator.js
new file mode 100644
index 0000000000..267656fcb5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-with-time-designator.js
@@ -0,0 +1,32 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: ISO 8601 time designator "T" allowed at the start of PlainTime strings
+includes: [temporalHelpers.js]
+features: [Temporal, arrow-function]
+---*/
+
+const instance = new Temporal.PlainTime(1, 0, 0, 0, 0, 1);
+const validStrings = [
+  "T00:30",
+  "t00:30",
+  "T0030",
+  "t0030",
+  "T00:30:00",
+  "t00:30:00",
+  "T003000",
+  "t003000",
+  "T00:30:00.000000000",
+  "t00:30:00.000000000",
+  "T003000.000000000",
+  "t003000.000000000",
+];
+validStrings.forEach((arg) => {
+  const result = instance.since(arg);
+  TemporalHelpers.assertDuration(result, 0, 0, 0, 0, 0, 30, 0, 0, 0, 1, `T prefix is accepted: ${arg}`);
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-with-utc-designator.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-with-utc-designator.js
new file mode 100644
index 0000000000..744bbec39a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-string-with-utc-designator.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: RangeError thrown if a string with UTC designator is used as a PlainTime
+features: [Temporal, arrow-function]
+---*/
+
+const invalidStrings = [
+  "2019-10-01T09:00:00Z",
+  "2019-10-01T09:00:00Z[UTC]",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => instance.since(arg),
+    "String with UTC designator should not be valid as a PlainTime"
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-wrong-type.js
new file mode 100644
index 0000000000..c842736a8c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-wrong-type.js
@@ -0,0 +1,39 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: >
+  Appropriate error thrown when argument cannot be converted to a valid string
+  or property bag for PlainTime
+features: [BigInt, Symbol, Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const rangeErrorTests = [
+  [undefined, "undefined"],
+  [null, "null"],
+  [true, "boolean"],
+  ["", "empty string"],
+  [1, "number that doesn't convert to a valid ISO string"],
+  [1n, "bigint"],
+];
+
+for (const [arg, description] of rangeErrorTests) {
+  assert.throws(RangeError, () => instance.since(arg), `${description} does not convert to a valid ISO string`);
+}
+
+const typeErrorTests = [
+  [Symbol(), "symbol"],
+  [{}, "plain object"],
+  [Temporal.PlainTime, "Temporal.PlainTime, object"],
+  [Temporal.PlainTime.prototype, "Temporal.PlainTime.prototype, object"],
+];
+
+for (const [arg, description] of typeErrorTests) {
+  assert.throws(TypeError, () => instance.since(arg), `${description} is not a valid property bag and does not convert to a string`);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-zoneddatetime-balance-negative-time-units.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-zoneddatetime-balance-negative-time-units.js
new file mode 100644
index 0000000000..fbde74a955
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-zoneddatetime-balance-negative-time-units.js
@@ -0,0 +1,46 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Negative time fields are balanced upwards if the argument is given as ZonedDateTime
+info: |
+    sec-temporal-balancetime steps 3–14:
+      3. Set _microsecond_ to _microsecond_ + floor(_nanosecond_ / 1000).
+      4. Set _nanosecond_ to _nanosecond_ modulo 1000.
+      5. Set _millisecond_ to _millisecond_ + floor(_microsecond_ / 1000).
+      6. Set _microsecond_ to _microsecond_ modulo 1000.
+      7. Set _second_ to _second_ + floor(_millisecond_ / 1000).
+      8. Set _millisecond_ to _millisecond_ modulo 1000.
+      9. Set _minute_ to _minute_ + floor(_second_ / 60).
+      10. Set _second_ to _second_ modulo 60.
+      11. Set _hour_ to _hour_ + floor(_minute_ / 60).
+      12. Set _minute_ to _minute_ modulo 60.
+      13. Let _days_ be floor(_hour_ / 24).
+      14. Set _hour_ to _hour_ modulo 24.
+    sec-temporal-balanceisodatetime step 1:
+      1. Let _balancedTime_ be ? BalanceTime(_hour_, _minute_, _second_, _millisecond_, _microsecond_, _nanosecond_).
+    sec-temporal-builtintimezonegetplaindatetimefor step 3:
+      3. Set _result_ to ? BalanceISODateTime(_result_.[[Year]], _result_.[[Month]], _result_.[[Day]], _result_.[[Hour]], _result_.[[Minute]], _result_.[[Second]], _result_.[[Millisecond]], _result_.[[Microsecond]], _result_.[[Nanosecond]] + _offsetNanoseconds_).
+    sec-temporal-totemporaltime step 3.b:
+      b. If _item_ has an [[InitializedTemporalZonedDateTime]] internal slot, then
+        ...
+        ii. 1. Set _plainDateTime_ to ? BuiltinTimeZoneGetPlainDateTimeFor(_item_.[[TimeZone]], _instant_, _item_.[[Calendar]]).
+    sec-temporal.plaintime.prototype.since step 3:
+      3. Set _other_ to ? ToTemporalTime(_other_).
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+// This code path is encountered if the time zone offset is negative and its
+// absolute value in nanoseconds is greater than the nanosecond field of the
+// exact time's epoch parts
+const tz = new Temporal.TimeZone("-00:00:00.000000002");
+const datetime = new Temporal.ZonedDateTime(3661_001_001_001n, tz);
+
+const diff = new Temporal.PlainTime().since(datetime);
+
+TemporalHelpers.assertDuration(diff, 0, 0, 0, 0, -1, -1, -1, -1, 0, -999);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-zoneddatetime-negative-epochnanoseconds.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-zoneddatetime-negative-epochnanoseconds.js
new file mode 100644
index 0000000000..64800bf4dd
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-zoneddatetime-negative-epochnanoseconds.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: A pre-epoch value is handled correctly by the modulo operation in GetISOPartsFromEpoch
+info: |
+    sec-temporal-getisopartsfromepoch step 1:
+      1. Let _remainderNs_ be the mathematical value whose sign is the sign of _epochNanoseconds_ and whose magnitude is abs(_epochNanoseconds_) modulo 10<sup>6</sup>.
+    sec-temporal-builtintimezonegetplaindatetimefor step 2:
+      2. Let _result_ be ! GetISOPartsFromEpoch(_instant_.[[Nanoseconds]]).
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const datetime = new Temporal.ZonedDateTime(-13849764_999_999_999n, "UTC");
+
+// This code path shows up anywhere we convert an exact time, before the Unix
+// epoch, with nonzero microseconds or nanoseconds, into a wall time.
+
+const instance = new Temporal.PlainTime(15);
+const result = instance.since(datetime);
+TemporalHelpers.assertDuration(result, 0, 0, 0, 0, -1, -50, -35, 0, 0, -1);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-non-integer.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-non-integer.js
new file mode 100644
index 0000000000..ec4f41496c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-non-integer.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: RangeError thrown if time zone reports an offset that is not an integer number of nanoseconds
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[3600_000_000_000.5, NaN, -Infinity, Infinity].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  assert.throws(RangeError, () => time.since(datetime));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js
new file mode 100644
index 0000000000..0a612be57d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js
@@ -0,0 +1,23 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: TypeError thrown if timeZone.getOffsetNanosecondsFor is not callable
+features: [BigInt, Symbol, Temporal, arrow-function]
+---*/
+
+[undefined, null, true, Math.PI, 'string', Symbol('sym'), 42n, {}].forEach((notCallable) => {
+  const timeZone = new Temporal.TimeZone("UTC");
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  timeZone.getOffsetNanosecondsFor = notCallable;
+  assert.throws(
+    TypeError,
+    () => time.since(datetime),
+    `Uncallable ${notCallable === null ? 'null' : typeof notCallable} getOffsetNanosecondsFor should throw TypeError`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-out-of-range.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-out-of-range.js
new file mode 100644
index 0000000000..519a5b2b60
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-out-of-range.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: RangeError thrown if time zone reports an offset that is out of range
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[-86400_000_000_000, 86400_000_000_000].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  assert.throws(RangeError, () => time.since(datetime));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-wrong-type.js
new file mode 100644
index 0000000000..43c42b4a0a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-wrong-type.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: TypeError thrown if time zone reports an offset that is not a Number
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[
+  undefined,
+  null,
+  true,
+  "+01:00",
+  Symbol(),
+  3600_000_000_000n,
+  {},
+  { valueOf() { return 3600_000_000_000; } },
+].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  assert.throws(TypeError, () => time.since(datetime));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/balance-negative-time-units.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/balance-negative-time-units.js
new file mode 100644
index 0000000000..94e93652da
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/balance-negative-time-units.js
@@ -0,0 +1,51 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Negative time fields are balanced upwards
+info: |
+    sec-temporal-balancetime steps 3–14:
+      3. Set _microsecond_ to _microsecond_ + floor(_nanosecond_ / 1000).
+      4. Set _nanosecond_ to _nanosecond_ modulo 1000.
+      5. Set _millisecond_ to _millisecond_ + floor(_microsecond_ / 1000).
+      6. Set _microsecond_ to _microsecond_ modulo 1000.
+      7. Set _second_ to _second_ + floor(_millisecond_ / 1000).
+      8. Set _millisecond_ to _millisecond_ modulo 1000.
+      9. Set _minute_ to _minute_ + floor(_second_ / 60).
+      10. Set _second_ to _second_ modulo 60.
+      11. Set _hour_ to _hour_ + floor(_minute_ / 60).
+      12. Set _minute_ to _minute_ modulo 60.
+      13. Let _days_ be floor(_hour_ / 24).
+      14. Set _hour_ to _hour_ modulo 24.
+    sec-temporal-differencetime step 8:
+      8. Let _bt_ be ? BalanceTime(_hours_, _minutes_, _seconds_, _milliseconds_, _microseconds_, _nanoseconds_).
+    sec-temporal.plaintime.prototype.since step 12:
+      12. Let _result_ be ! DifferenceTime(_other_.[[ISOHour]], _other_.[[ISOMinute]], _other_.[[ISOSecond]], _other_.[[ISOMillisecond]], _other_.[[ISOMicrosecond]], _other_.[[ISONanosecond]], _temporalTime_.[[ISOHour]], _temporalTime_.[[ISOMinute]], _temporalTime_.[[ISOSecond]], _temporalTime_.[[ISOMillisecond]], _temporalTime_.[[ISOMicrosecond]], _temporalTime_.[[ISONanosecond]]).
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(1, 1, 1, 1, 1, 1);
+
+const result1 = time.since(new Temporal.PlainTime(0, 0, 0, 0, 0, 2));
+TemporalHelpers.assertDuration(result1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 999, "nanoseconds balance");
+
+const result2 = time.since(new Temporal.PlainTime(0, 0, 0, 0, 2));
+TemporalHelpers.assertDuration(result2, 0, 0, 0, 0, 1, 1, 1, 0, 999, 1, "microseconds balance");
+
+const result3 = time.since(new Temporal.PlainTime(0, 0, 0, 2));
+TemporalHelpers.assertDuration(result3, 0, 0, 0, 0, 1, 1, 0, 999, 1, 1, "milliseconds balance");
+
+const result4 = time.since(new Temporal.PlainTime(0, 0, 2));
+TemporalHelpers.assertDuration(result4, 0, 0, 0, 0, 1, 0, 59, 1, 1, 1, "seconds balance");
+
+const result5 = time.since(new Temporal.PlainTime(0, 2));
+TemporalHelpers.assertDuration(result5, 0, 0, 0, 0, 0, 59, 1, 1, 1, 1, "minutes balance");
+
+// This one is different because hours are later balanced again in BalanceDuration
+const result6 = time.since(new Temporal.PlainTime(2));
+TemporalHelpers.assertDuration(result6, 0, 0, 0, 0, 0, -58, -58, -998, -998, -999, "hours balance");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/basic.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/basic.js
new file mode 100644
index 0000000000..00e78a3a89
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/basic.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Basic usage
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const one = new Temporal.PlainTime(15, 23, 30, 123, 456, 789);
+const two = new Temporal.PlainTime(14, 23, 30, 123, 456, 789);
+const three = new Temporal.PlainTime(13, 30, 30, 123, 456, 789);
+
+TemporalHelpers.assertDuration(one.since(two),
+  0, 0, 0, 0, /* hours = */ 1, 0, 0, 0, 0, 0);
+TemporalHelpers.assertDuration(two.since(one),
+  0, 0, 0, 0, /* hours = */ -1, 0, 0, 0, 0, 0);
+TemporalHelpers.assertDuration(one.since(three),
+  0, 0, 0, 0, /* hours = */ 1, 53, 0, 0, 0, 0);
+TemporalHelpers.assertDuration(three.since(one),
+  0, 0, 0, 0, /* hours = */ -1, -53, 0, 0, 0, 0);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/branding.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/branding.js
new file mode 100644
index 0000000000..f0948c72a1
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/branding.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Throw a TypeError if the receiver is invalid
+features: [Symbol, Temporal]
+---*/
+
+const since = Temporal.PlainTime.prototype.since;
+
+assert.sameValue(typeof since, "function");
+
+const args = [new Temporal.PlainTime(12)];
+
+assert.throws(TypeError, () => since.apply(undefined, args), "undefined");
+assert.throws(TypeError, () => since.apply(null, args), "null");
+assert.throws(TypeError, () => since.apply(true, args), "true");
+assert.throws(TypeError, () => since.apply("", args), "empty string");
+assert.throws(TypeError, () => since.apply(Symbol(), args), "symbol");
+assert.throws(TypeError, () => since.apply(1, args), "1");
+assert.throws(TypeError, () => since.apply({}, args), "plain object");
+assert.throws(TypeError, () => since.apply(Temporal.PlainTime, args), "Temporal.PlainTime");
+assert.throws(TypeError, () => since.apply(Temporal.PlainTime.prototype, args), "Temporal.PlainTime.prototype");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/builtin.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/builtin.js
new file mode 100644
index 0000000000..b7d0c5a190
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/builtin.js
@@ -0,0 +1,36 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: >
+    Tests that Temporal.PlainTime.prototype.since
+    meets the requirements for built-in objects defined by the
+    introduction of chapter 17 of the ECMAScript Language Specification.
+info: |
+    Built-in functions that are not constructors do not have a "prototype" property unless
+    otherwise specified in the description of a particular function.
+
+    Unless specified otherwise, a built-in object that is callable as a function is a built-in
+    function object with the characteristics described in 10.3. Unless specified otherwise, the
+    [[Extensible]] internal slot of a built-in object initially has the value true.
+
+    Unless otherwise specified every built-in function and every built-in constructor has the
+    Function prototype object [...] as the value of its [[Prototype]] internal slot.
+features: [Temporal]
+---*/
+
+assert.sameValue(Object.isExtensible(Temporal.PlainTime.prototype.since),
+  true, "Built-in objects must be extensible.");
+
+assert.sameValue(Object.prototype.toString.call(Temporal.PlainTime.prototype.since),
+  "[object Function]", "Object.prototype.toString");
+
+assert.sameValue(Object.getPrototypeOf(Temporal.PlainTime.prototype.since),
+  Function.prototype, "prototype");
+
+assert.sameValue(Temporal.PlainTime.prototype.since.hasOwnProperty("prototype"),
+  false, "prototype property");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/calendar-temporal-object.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/calendar-temporal-object.js
new file mode 100644
index 0000000000..2e0d8c9efb
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/calendar-temporal-object.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Fast path for converting other Temporal objects to Temporal.Calendar by reading internal slots
+info: |
+    sec-temporal.plaintime.prototype.since step 3:
+      3. Set _other_ to ? ToTemporalTime(_other_).
+    sec-temporal-totemporaltime step 3.d:
+      d. If _calendar_ is not *undefined*, then
+        i. Set _calendar_ to ? ToTemporalCalendar(_calendar_).
+        ii. If ? ToString(_calendar_) is not *"iso8601"*, then
+          1. Throw a *RangeError* exception.
+    sec-temporal-totemporalcalendar step 1.a:
+      a. If _temporalCalendarLike_ has an [[InitializedTemporalDate]], [[InitializedTemporalDateTime]], [[InitializedTemporalMonthDay]], [[InitializedTemporalYearMonth]], or [[InitializedTemporalZonedDateTime]] internal slot, then
+        i. Return _temporalCalendarLike_.[[Calendar]].
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+TemporalHelpers.checkToTemporalCalendarFastPath((temporalObject) => {
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  assert.throws(RangeError, () => time.since({ hour: 12, minute: 30, calendar: temporalObject }));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/largestunit-invalid-string.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/largestunit-invalid-string.js
new file mode 100644
index 0000000000..05d9bc9b4c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/largestunit-invalid-string.js
@@ -0,0 +1,39 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: RangeError thrown when largestUnit option not one of the allowed string values
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 0, 0, 0);
+const later = new Temporal.PlainTime(13, 35, 57, 987, 654, 321);
+const badValues = [
+  "era",
+  "eraYear",
+  "year",
+  "month",
+  "week",
+  "day",
+  "millisecond\0",
+  "mill\u0131second",
+  "SECOND",
+  "eras",
+  "eraYears",
+  "years",
+  "months",
+  "weeks",
+  "days",
+  "milliseconds\0",
+  "mill\u0131seconds",
+  "SECONDS",
+  "other string"
+];
+for (const largestUnit of badValues) {
+  assert.throws(RangeError, () => later.since(earlier, { largestUnit }),
+    `"${largestUnit}" is not a valid value for largestUnit`);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/largestunit-plurals-accepted.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/largestunit-plurals-accepted.js
new file mode 100644
index 0000000000..fb0480e73b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/largestunit-plurals-accepted.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Plural units are accepted as well for the largestUnit option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+const later = new Temporal.PlainTime(13, 35, 57, 988, 655, 322);
+const validUnits = [
+  "hour",
+  "minute",
+  "second",
+  "millisecond",
+  "microsecond",
+  "nanosecond",
+];
+TemporalHelpers.checkPluralUnitsAccepted((largestUnit) => later.since(earlier, { largestUnit }), validUnits);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/largestunit-smallestunit-mismatch.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/largestunit-smallestunit-mismatch.js
new file mode 100644
index 0000000000..d7619bf650
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/largestunit-smallestunit-mismatch.js
@@ -0,0 +1,22 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: RangeError thrown when smallestUnit is larger than largestUnit
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 0, 0, 0);
+const later = new Temporal.PlainTime(13, 35, 57, 987, 654, 321);
+const units = ["hours", "minutes", "seconds", "milliseconds", "microseconds", "nanoseconds"];
+for (let largestIdx = 1; largestIdx < units.length; largestIdx++) {
+  for (let smallestIdx = 0; smallestIdx < largestIdx; smallestIdx++) {
+    const largestUnit = units[largestIdx];
+    const smallestUnit = units[smallestIdx];
+    assert.throws(RangeError, () => later.since(earlier, { largestUnit, smallestUnit }));
+  }
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/largestunit-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/largestunit-undefined.js
new file mode 100644
index 0000000000..c4322453f2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/largestunit-undefined.js
@@ -0,0 +1,20 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Fallback value for largestUnit option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 0, 0, 0);
+const later = new Temporal.PlainTime(13, 35, 57, 987, 654, 321);
+
+const explicit = later.since(earlier, { largestUnit: undefined });
+TemporalHelpers.assertDuration(explicit, 0, 0, 0, 0, 1, 1, 1, 987, 654, 321, "default largestUnit is hour");
+const implicit = later.since(earlier, {});
+TemporalHelpers.assertDuration(implicit, 0, 0, 0, 0, 1, 1, 1, 987, 654, 321, "default largestUnit is hour");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/largestunit-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/largestunit-wrong-type.js
new file mode 100644
index 0000000000..3cbe135c62
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/largestunit-wrong-type.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Type conversions for largestUnit option
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 0, 0, 0);
+const later = new Temporal.PlainTime(13, 35, 57, 987, 654, 321);
+TemporalHelpers.checkStringOptionWrongType("largestUnit", "second",
+  (largestUnit) => later.since(earlier, { largestUnit }),
+  (result, descr) => TemporalHelpers.assertDuration(result, 0, 0, 0, 0, 0, 0, 3661, 987, 654, 321, descr),
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/largestunit.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/largestunit.js
new file mode 100644
index 0000000000..7ed94eca9b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/largestunit.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: PlainTime.since with various largestUnit values.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+const fourFortyEight = new Temporal.PlainTime(4, 48, 55);
+const elevenFiftyNine = new Temporal.PlainTime(11, 59, 58);
+TemporalHelpers.assertDuration(elevenFiftyNine.since(fourFortyEight), 0, 0, 0, 0, 7, 11, 3, 0, 0, 0, 'does not include higher units than necessary (largest unit unspecified)');
+TemporalHelpers.assertDuration(elevenFiftyNine.since(fourFortyEight, { largestUnit: 'auto' }), 0, 0, 0, 0, 7, 11, 3, 0, 0, 0,  'does not include higher units than necessary (largest unit is auto)');
+TemporalHelpers.assertDuration(elevenFiftyNine.since(fourFortyEight, { largestUnit: 'hours' }), 0, 0, 0, 0, 7, 11, 3, 0, 0, 0,  'does not include higher units than necessary (largest unit is hours)');
+TemporalHelpers.assertDuration(elevenFiftyNine.since(fourFortyEight, { largestUnit: 'minutes' }), 0, 0, 0, 0, 0, 431, 3, 0, 0, 0, 'does not include higher units than necessary (largest unit is minutes)');
+TemporalHelpers.assertDuration(elevenFiftyNine.since(fourFortyEight, { largestUnit: 'seconds' }), 0, 0, 0, 0, 0, 0, 25863, 0, 0, 0, 'does not include higher units than necessary (largest unit is seconds)');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/leap-second.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/leap-second.js
new file mode 100644
index 0000000000..0c56d70f63
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/leap-second.js
@@ -0,0 +1,30 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Leap second is a valid ISO string for PlainTime
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(23, 59, 59);
+
+let arg = "2016-12-31T23:59:60";
+const result1 = instance.since(arg);
+TemporalHelpers.assertDuration(
+  result1,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  "leap second is a valid ISO string for PlainTime"
+);
+
+arg = { year: 2016, month: 12, day: 31, hour: 23, minute: 59, second: 60 };
+const result2 = instance.since(arg);
+TemporalHelpers.assertDuration(
+  result2,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  "second: 60 is ignored in property bag for PlainTime"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/length.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/length.js
new file mode 100644
index 0000000000..e1a665f4a9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/length.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Temporal.PlainTime.prototype.since.length is 1
+info: |
+    Every built-in function object, including constructors, has a "length" property whose value is
+    an integer. Unless otherwise specified, this value is equal to the largest number of named
+    arguments shown in the subclause headings for the function description. Optional parameters
+    (which are indicated with brackets: [ ]) or rest parameters (which are shown using the form
+    «...name») are not included in the default argument count.
+
+    Unless otherwise specified, the "length" property of a built-in function object has the
+    attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.since, "length", {
+  value: 1,
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/name.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/name.js
new file mode 100644
index 0000000000..a6f787515c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/name.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Temporal.PlainTime.prototype.since.name is "since".
+info: |
+    Every built-in function object, including constructors, that is not identified as an anonymous
+    function has a "name" property whose value is a String. Unless otherwise specified, this value
+    is the name that is given to the function in this specification.
+
+    Unless otherwise specified, the "name" property of a built-in function object, if it exists,
+    has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.since, "name", {
+  value: "since",
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/not-a-constructor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/not-a-constructor.js
new file mode 100644
index 0000000000..e12fd8bfcf
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/not-a-constructor.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: >
+  Temporal.PlainTime.prototype.since does not implement [[Construct]], is not new-able
+info: |
+    Built-in function objects that are not identified as constructors do not implement the
+    [[Construct]] internal method unless otherwise specified in the description of a particular
+    function.
+includes: [isConstructor.js]
+features: [Reflect.construct, Temporal]
+---*/
+
+assert.throws(TypeError, () => {
+  new Temporal.PlainTime.prototype.since();
+}, "Calling as constructor");
+
+assert.sameValue(isConstructor(Temporal.PlainTime.prototype.since), false,
+  "isConstructor(Temporal.PlainTime.prototype.since)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/options-invalid.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/options-invalid.js
new file mode 100644
index 0000000000..fcab44fb64
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/options-invalid.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: TypeError thrown when a primitive is passed as the options argument
+features: [Temporal]
+---*/
+
+const values = [null, true, "hello", Symbol("foo"), 1, 1n];
+const time = new Temporal.PlainTime(15, 23, 30, 123, 456, 789);
+const one = new Temporal.PlainTime(16, 23, 30, 123, 456, 789);
+
+for (const badOptions of values) {
+  assert.throws(TypeError, () => time.since(one, badOptions));
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/options-object.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/options-object.js
new file mode 100644
index 0000000000..db9f9d79d1
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/options-object.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Empty or a function object may be used as options
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime();
+
+const result1 = instance.since(new Temporal.PlainTime(12, 34, 56), {});
+TemporalHelpers.assertDuration(
+  result1, 0, 0, 0, 0, -12, -34, -56, 0, 0, 0,
+  "options may be an empty plain object"
+);
+
+const result2 = instance.since(new Temporal.PlainTime(12, 34, 56), () => {});
+TemporalHelpers.assertDuration(
+  result2, 0, 0, 0, 0, -12, -34, -56, 0, 0, 0,
+  "options may be a function object"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/options-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/options-undefined.js
new file mode 100644
index 0000000000..b2a3909319
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/options-undefined.js
@@ -0,0 +1,22 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Verify that undefined options are handled correctly.
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+const later = new Temporal.PlainTime(18, 34, 56, 987, 654, 322);
+
+const explicit = later.since(earlier, undefined);
+assert.sameValue(explicit.hours, 6, "default largest unit is hours");
+assert.sameValue(explicit.nanoseconds, 1, "default smallest unit is nanoseconds and no rounding");
+
+const implicit = later.since(earlier);
+assert.sameValue(implicit.hours, 6, "default largest unit is hours");
+assert.sameValue(implicit.nanoseconds, 1, "default smallest unit is nanoseconds and no rounding");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/options-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/options-wrong-type.js
new file mode 100644
index 0000000000..2096b32715
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/options-wrong-type.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: TypeError thrown when options argument is a primitive
+features: [BigInt, Symbol, Temporal]
+---*/
+
+const badOptions = [
+  null,
+  true,
+  "some string",
+  Symbol(),
+  1,
+  2n,
+];
+
+const instance = new Temporal.PlainTime();
+for (const value of badOptions) {
+  assert.throws(TypeError, () => instance.since(new Temporal.PlainTime(12, 34, 56), value),
+    `TypeError on wrong options type ${typeof value}`);
+};
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/order-of-operations.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/order-of-operations.js
new file mode 100644
index 0000000000..ea450ee6fa
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/order-of-operations.js
@@ -0,0 +1,82 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Properties on an object passed to since() are accessed in the correct order
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const expected = [
+  // ToTemporalTime
+  "get other.calendar",
+  "get other.calendar.toString",
+  "call other.calendar.toString",
+  "get other.hour",
+  "get other.hour.valueOf",
+  "call other.hour.valueOf",
+  "get other.microsecond",
+  "get other.microsecond.valueOf",
+  "call other.microsecond.valueOf",
+  "get other.millisecond",
+  "get other.millisecond.valueOf",
+  "call other.millisecond.valueOf",
+  "get other.minute",
+  "get other.minute.valueOf",
+  "call other.minute.valueOf",
+  "get other.nanosecond",
+  "get other.nanosecond.valueOf",
+  "call other.nanosecond.valueOf",
+  "get other.second",
+  "get other.second.valueOf",
+  "call other.second.valueOf",
+  // CopyDataProperties
+  "ownKeys options",
+  "getOwnPropertyDescriptor options.roundingIncrement",
+  "get options.roundingIncrement",
+  "getOwnPropertyDescriptor options.roundingMode",
+  "get options.roundingMode",
+  "getOwnPropertyDescriptor options.largestUnit",
+  "get options.largestUnit",
+  "getOwnPropertyDescriptor options.smallestUnit",
+  "get options.smallestUnit",
+  "getOwnPropertyDescriptor options.additional",
+  "get options.additional",
+  // GetDifferenceSettings
+  "get options.largestUnit.toString",
+  "call options.largestUnit.toString",
+  "get options.roundingIncrement.valueOf",
+  "call options.roundingIncrement.valueOf",
+  "get options.roundingMode.toString",
+  "call options.roundingMode.toString",
+  "get options.smallestUnit.toString",
+  "call options.smallestUnit.toString",
+];
+const actual = [];
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const other = TemporalHelpers.propertyBagObserver(actual, {
+  hour: 1.7,
+  minute: 1.7,
+  second: 1.7,
+  millisecond: 1.7,
+  microsecond: 1.7,
+  nanosecond: 1.7,
+  calendar: "iso8601",
+}, "other");
+
+const options = TemporalHelpers.propertyBagObserver(actual, {
+  roundingIncrement: 1,
+  roundingMode: "trunc",
+  largestUnit: "hours",
+  smallestUnit: "nanoseconds",
+  additional: true,
+}, "options");
+
+const result = instance.since(other, options);
+assert.compareArray(actual, expected, "order of operations");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/plaintime-propertybag-no-time-units.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/plaintime-propertybag-no-time-units.js
new file mode 100644
index 0000000000..055f77f382
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/plaintime-propertybag-no-time-units.js
@@ -0,0 +1,21 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Missing time units in property bag default to 0
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(1, 0, 0, 0, 0, 1);
+
+const props = {};
+assert.throws(TypeError, () => instance.since(props), "TypeError if no properties are present");
+
+props.minute = 30;
+const result = instance.since(props);
+TemporalHelpers.assertDuration(result, 0, 0, 0, 0, 0, 30, 0, 0, 0, 1, "missing time units default to 0");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/prop-desc.js
new file mode 100644
index 0000000000..abe7123e7a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/prop-desc.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: The "since" property of Temporal.PlainTime.prototype
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+assert.sameValue(
+  typeof Temporal.PlainTime.prototype.since,
+  "function",
+  "`typeof PlainTime.prototype.since` is `function`"
+);
+
+verifyProperty(Temporal.PlainTime.prototype, "since", {
+  writable: true,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/result-sub-second.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/result-sub-second.js
new file mode 100644
index 0000000000..c8ef9d5980
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/result-sub-second.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Supports sub-second precision
+includes: [temporalHelpers.js]
+features: [Temporal, arrow-function]
+---*/
+
+const time1 = Temporal.PlainTime.from("10:23:15");
+const time2 = Temporal.PlainTime.from("17:15:57.250250250");
+
+TemporalHelpers.assertDuration(time2.since(time1, { largestUnit: "milliseconds" }),
+  0, 0, 0, 0, 0, 0, 0, /* milliseconds = */ 24762250, 250, 250, "milliseconds");
+
+TemporalHelpers.assertDuration(time2.since(time1, { largestUnit: "microseconds" }),
+  0, 0, 0, 0, 0, 0, 0, /* milliseconds = */ 0, 24762250250, 250, "microseconds");
+
+TemporalHelpers.assertDuration(time2.since(time1, { largestUnit: "nanoseconds" }),
+  0, 0, 0, 0, 0, 0, 0, /* milliseconds = */ 0, 0, 24762250250250, "nanoseconds");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-hours.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-hours.js
new file mode 100644
index 0000000000..f51a5f6fd0
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-hours.js
@@ -0,0 +1,37 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Valid values for roundingIncrement option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(3, 12, 34, 123, 456, 789);
+const later = new Temporal.PlainTime(13, 47, 57, 988, 655, 322);
+
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "hours", roundingIncrement: 1 }),
+  0, 0, 0, 0, 10, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "hours", roundingIncrement: 2 }),
+  0, 0, 0, 0, 10, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "hours", roundingIncrement: 3 }),
+  0, 0, 0, 0, 9, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "hours", roundingIncrement: 4 }),
+  0, 0, 0, 0, 8, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "hours", roundingIncrement: 6 }),
+  0, 0, 0, 0, 6, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "hours", roundingIncrement: 8 }),
+  0, 0, 0, 0, 8, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "hours", roundingIncrement: 12 }),
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, "hours");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-invalid.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-invalid.js
new file mode 100644
index 0000000000..2d56ee6818
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-invalid.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Tests roundingIncrement restrictions.
+features: [Temporal]
+---*/
+
+const earlier = Temporal.PlainTime.from("08:22:36.123456789");
+const later = Temporal.PlainTime.from("12:39:40.987654321");
+
+assert.throws(RangeError, () => later.since(earlier, { smallestUnit: "hours", roundingIncrement: 11 }));
+assert.throws(RangeError, () => later.since(earlier, { smallestUnit: "minutes", roundingIncrement: 29 }));
+assert.throws(RangeError, () => later.since(earlier, { smallestUnit: "seconds", roundingIncrement: 29 }));
+assert.throws(RangeError, () => later.since(earlier, { smallestUnit: "milliseconds", roundingIncrement: 29 }));
+assert.throws(RangeError, () => later.since(earlier, { smallestUnit: "microseconds", roundingIncrement: 29 }));
+assert.throws(RangeError, () => later.since(earlier, { smallestUnit: "nanoseconds", roundingIncrement: 29 }));
+assert.throws(RangeError, () => later.since(earlier, { smallestUnit: "hours", roundingIncrement: 24 }));
+assert.throws(RangeError, () => later.since(earlier, { smallestUnit: "minutes", roundingIncrement: 60 }));
+assert.throws(RangeError, () => later.since(earlier, { smallestUnit: "seconds", roundingIncrement: 60 }));
+assert.throws(RangeError, () => later.since(earlier, { smallestUnit: "milliseconds", roundingIncrement: 1000 }));
+assert.throws(RangeError, () => later.since(earlier, { smallestUnit: "microseconds", roundingIncrement: 1000 }));
+assert.throws(RangeError, () => later.since(earlier, { smallestUnit: "nanoseconds", roundingIncrement: 1000 }));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-microseconds.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-microseconds.js
new file mode 100644
index 0000000000..34ba8a5761
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-microseconds.js
@@ -0,0 +1,61 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Valid values for roundingIncrement option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(3, 12, 34, 123, 456, 789);
+const later = new Temporal.PlainTime(13, 47, 57, 988, 655, 322);
+
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "microseconds", roundingIncrement: 1 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "microseconds", roundingIncrement: 2 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "microseconds", roundingIncrement: 4 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 196, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "microseconds", roundingIncrement: 5 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 195, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "microseconds", roundingIncrement: 8 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 192, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "microseconds", roundingIncrement: 10 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 190, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "microseconds", roundingIncrement: 20 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 180, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "microseconds", roundingIncrement: 25 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 175, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "microseconds", roundingIncrement: 40 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 160, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "microseconds", roundingIncrement: 50 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 150, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "microseconds", roundingIncrement: 100 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 100, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "microseconds", roundingIncrement: 125 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 125, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "microseconds", roundingIncrement: 200 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 0, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "microseconds", roundingIncrement: 250 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 0, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "microseconds", roundingIncrement: 500 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 0, 0, "microseconds");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-milliseconds.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-milliseconds.js
new file mode 100644
index 0000000000..f67c767a57
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-milliseconds.js
@@ -0,0 +1,61 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Valid values for roundingIncrement option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(3, 12, 34, 123, 456, 789);
+const later = new Temporal.PlainTime(13, 47, 57, 988, 655, 322);
+
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "milliseconds", roundingIncrement: 1 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "milliseconds", roundingIncrement: 2 }),
+  0, 0, 0, 0, 10, 35, 23, 864, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "milliseconds", roundingIncrement: 4 }),
+  0, 0, 0, 0, 10, 35, 23, 864, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "milliseconds", roundingIncrement: 5 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "milliseconds", roundingIncrement: 8 }),
+  0, 0, 0, 0, 10, 35, 23, 864, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "milliseconds", roundingIncrement: 10 }),
+  0, 0, 0, 0, 10, 35, 23, 860, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "milliseconds", roundingIncrement: 20 }),
+  0, 0, 0, 0, 10, 35, 23, 860, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "milliseconds", roundingIncrement: 25 }),
+  0, 0, 0, 0, 10, 35, 23, 850, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "milliseconds", roundingIncrement: 40 }),
+  0, 0, 0, 0, 10, 35, 23, 840, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "milliseconds", roundingIncrement: 50 }),
+  0, 0, 0, 0, 10, 35, 23, 850, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "milliseconds", roundingIncrement: 100 }),
+  0, 0, 0, 0, 10, 35, 23, 800, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "milliseconds", roundingIncrement: 125 }),
+  0, 0, 0, 0, 10, 35, 23, 750, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "milliseconds", roundingIncrement: 200 }),
+  0, 0, 0, 0, 10, 35, 23, 800, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "milliseconds", roundingIncrement: 250 }),
+  0, 0, 0, 0, 10, 35, 23, 750, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "milliseconds", roundingIncrement: 500 }),
+  0, 0, 0, 0, 10, 35, 23, 500, 0, 0, "milliseconds");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-minutes.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-minutes.js
new file mode 100644
index 0000000000..3e445b82a9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-minutes.js
@@ -0,0 +1,49 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Valid values for roundingIncrement option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(3, 12, 34, 123, 456, 789);
+const later = new Temporal.PlainTime(13, 47, 57, 988, 655, 322);
+
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "minutes", roundingIncrement: 1 }),
+  0, 0, 0, 0, 10, 35, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "minutes", roundingIncrement: 2 }),
+  0, 0, 0, 0, 10, 34, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "minutes", roundingIncrement: 3 }),
+  0, 0, 0, 0, 10, 33, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "minutes", roundingIncrement: 4 }),
+  0, 0, 0, 0, 10, 32, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "minutes", roundingIncrement: 5 }),
+  0, 0, 0, 0, 10, 35, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "minutes", roundingIncrement: 6 }),
+  0, 0, 0, 0, 10, 30, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "minutes", roundingIncrement: 10 }),
+  0, 0, 0, 0, 10, 30, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "minutes", roundingIncrement: 12 }),
+  0, 0, 0, 0, 10, 24, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "minutes", roundingIncrement: 15 }),
+  0, 0, 0, 0, 10, 30, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "minutes", roundingIncrement: 20 }),
+  0, 0, 0, 0, 10, 20, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "minutes", roundingIncrement: 30 }),
+  0, 0, 0, 0, 10, 30, 0, 0, 0, 0, "minutes");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-nan.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-nan.js
new file mode 100644
index 0000000000..8b3a653616
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-nan.js
@@ -0,0 +1,22 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: RangeError thrown when roundingIncrement option is NaN
+info: |
+    sec-getoption step 8.b:
+      b. If _value_ is *NaN*, throw a *RangeError* exception.
+    sec-temporal-totemporalroundingincrement step 5:
+      5. Let _increment_ be ? GetOption(_normalizedOptions_, *"roundingIncrement"*, « Number », *undefined*, 1).
+    sec-temporal.plaintime.prototype.since step 11:
+      11. Let _roundingIncrement_ be ? ToTemporalRoundingIncrement(_options_, _maximum_, *false*).
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+const later = new Temporal.PlainTime(13, 35, 57, 988, 655, 322);
+assert.throws(RangeError, () => later.since(earlier, { roundingIncrement: NaN }));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-nanoseconds.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-nanoseconds.js
new file mode 100644
index 0000000000..e88b145a07
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-nanoseconds.js
@@ -0,0 +1,61 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Valid values for roundingIncrement option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(3, 12, 34, 123, 456, 789);
+const later = new Temporal.PlainTime(13, 47, 57, 988, 655, 322);
+
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "nanoseconds", roundingIncrement: 1 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 533, "nanoseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "nanoseconds", roundingIncrement: 2 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 532, "nanoseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "nanoseconds", roundingIncrement: 4 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 532, "nanoseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "nanoseconds", roundingIncrement: 5 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 530, "nanoseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "nanoseconds", roundingIncrement: 8 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 528, "nanoseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "nanoseconds", roundingIncrement: 10 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 530, "nanoseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "nanoseconds", roundingIncrement: 20 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 520, "nanoseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "nanoseconds", roundingIncrement: 25 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 525, "nanoseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "nanoseconds", roundingIncrement: 40 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 520, "nanoseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "nanoseconds", roundingIncrement: 50 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 500, "nanoseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "nanoseconds", roundingIncrement: 100 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 500, "nanoseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "nanoseconds", roundingIncrement: 125 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 500, "nanoseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "nanoseconds", roundingIncrement: 200 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 400, "nanoseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "nanoseconds", roundingIncrement: 250 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 500, "nanoseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "nanoseconds", roundingIncrement: 500 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 500, "nanoseconds");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-non-integer.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-non-integer.js
new file mode 100644
index 0000000000..5c61615576
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-non-integer.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Rounding for roundingIncrement option
+info: |
+    ToTemporalRoundingIncrement ( _normalizedOptions_ )
+
+    1. Let _increment_ be ? GetOption(_normalizedOptions_, *"roundingIncrement"*, *"number"*, *undefined*, *1*<sub>𝔽</sub>).
+    2. If _increment_ is not finite, throw a *RangeError* exception.
+    3. Let _integerIncrement_ be truncate(ℝ(_increment_)).
+    4. If _integerIncrement_ < 1 or _integerIncrement_ > 10<sup>9</sup>, throw a *RangeError* exception.
+    5. Return _integerIncrement_.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 0, 0, 0);
+const later = new Temporal.PlainTime(12, 34, 56, 0, 0, 5);
+const result = later.since(earlier, { roundingIncrement: 2.5, roundingMode: "trunc" });
+TemporalHelpers.assertDuration(result, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, "roundingIncrement 2.5 truncates to 2");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-out-of-range.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-out-of-range.js
new file mode 100644
index 0000000000..c2798116e7
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-out-of-range.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: RangeError thrown when roundingIncrement option out of range
+info: |
+    ToTemporalRoundingIncrement ( _normalizedOptions_ )
+
+    1. Let _increment_ be ? GetOption(_normalizedOptions_, *"roundingIncrement"*, *"number"*, *undefined*, *1*<sub>𝔽</sub>).
+    2. If _increment_ is not finite, throw a *RangeError* exception.
+    3. Let _integerIncrement_ be truncate(ℝ(_increment_)).
+    4. If _integerIncrement_ < 1 or _integerIncrement_ > 10<sup>9</sup>, throw a *RangeError* exception.
+    5. Return _integerIncrement_.
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 0, 0, 0);
+const later = new Temporal.PlainTime(12, 34, 56, 0, 0, 5);
+assert.throws(RangeError, () => later.since(earlier, { roundingIncrement: -Infinity }));
+assert.throws(RangeError, () => later.since(earlier, { roundingIncrement: -1 }));
+assert.throws(RangeError, () => later.since(earlier, { roundingIncrement: 0 }));
+assert.throws(RangeError, () => later.since(earlier, { roundingIncrement: 0.9 }));
+assert.throws(RangeError, () => later.since(earlier, { roundingIncrement: 1e9 + 1 }));
+assert.throws(RangeError, () => later.since(earlier, { roundingIncrement: Infinity }));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-seconds.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-seconds.js
new file mode 100644
index 0000000000..5c229501a2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-seconds.js
@@ -0,0 +1,49 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Valid values for roundingIncrement option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(3, 12, 34, 123, 456, 789);
+const later = new Temporal.PlainTime(13, 47, 57, 988, 655, 322);
+
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "seconds", roundingIncrement: 1 }),
+  0, 0, 0, 0, 10, 35, 23, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "seconds", roundingIncrement: 2 }),
+  0, 0, 0, 0, 10, 35, 22, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "seconds", roundingIncrement: 3 }),
+  0, 0, 0, 0, 10, 35, 21, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "seconds", roundingIncrement: 4 }),
+  0, 0, 0, 0, 10, 35, 20, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "seconds", roundingIncrement: 5 }),
+  0, 0, 0, 0, 10, 35, 20, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "seconds", roundingIncrement: 6 }),
+  0, 0, 0, 0, 10, 35, 18, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "seconds", roundingIncrement: 10 }),
+  0, 0, 0, 0, 10, 35, 20, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "seconds", roundingIncrement: 12 }),
+  0, 0, 0, 0, 10, 35, 12, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "seconds", roundingIncrement: 15 }),
+  0, 0, 0, 0, 10, 35, 15, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "seconds", roundingIncrement: 20 }),
+  0, 0, 0, 0, 10, 35, 20, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "seconds", roundingIncrement: 30 }),
+  0, 0, 0, 0, 10, 35, 0, 0, 0, 0, "seconds");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-undefined.js
new file mode 100644
index 0000000000..18e6f45ccd
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-undefined.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Fallback value for roundingIncrement option
+info: |
+    sec-getoption step 3:
+      3. If _value_ is *undefined*, return _fallback_.
+    sec-temporal-totemporalroundingincrement step 5:
+      5. Let _increment_ be ? GetOption(_normalizedOptions_, *"roundingIncrement"*, « Number », *undefined*, 1).
+    sec-temporal.plaintime.prototype.since step 11:
+      11. Let _roundingIncrement_ be ? ToTemporalRoundingIncrement(_options_, _maximum_, *false*).
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+const later = new Temporal.PlainTime(13, 35, 57, 988, 655, 322);
+
+const explicit = later.since(earlier, { roundingIncrement: undefined });
+TemporalHelpers.assertDuration(explicit, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, "default roundingIncrement is 1");
+
+const implicit = later.since(earlier, {});
+TemporalHelpers.assertDuration(implicit, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, "default roundingIncrement is 1");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-wrong-type.js
new file mode 100644
index 0000000000..df2cc5a461
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingincrement-wrong-type.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Type conversions for roundingIncrement option
+info: |
+    sec-getoption step 8.a:
+      a. Set _value_ to ? ToNumber(value).
+    sec-temporal-totemporalroundingincrement step 5:
+      5. Let _increment_ be ? GetOption(_normalizedOptions_, *"roundingIncrement"*, « Number », *undefined*, 1).
+    sec-temporal.plaintime.prototype.since step 11:
+      11. Let _roundingIncrement_ be ? ToTemporalRoundingIncrement(_options_, _maximum_, *false*).
+includes: [temporalHelpers.js, compareArray.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+const later = new Temporal.PlainTime(13, 35, 57, 988, 655, 322);
+
+TemporalHelpers.checkRoundingIncrementOptionWrongType(
+  (roundingIncrement) => later.since(earlier, { roundingIncrement }),
+  (result, descr) => TemporalHelpers.assertDuration(result, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, descr),
+  (result, descr) => TemporalHelpers.assertDuration(result, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, descr),
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-ceil.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-ceil.js
new file mode 100644
index 0000000000..21cba55cee
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-ceil.js
@@ -0,0 +1,41 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Tests calculations with roundingMode "ceil".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(8, 22, 36, 123, 456, 789);
+const later = new Temporal.PlainTime(12, 39, 40, 987, 654, 289);
+
+const expected = [
+  ["hours", [0, 0, 0, 0, 5], [0, 0, 0, 0, -4]],
+  ["minutes", [0, 0, 0, 0, 4, 18], [0, 0, 0, 0, -4, -17]],
+  ["seconds", [0, 0, 0, 0, 4, 17, 5], [0, 0, 0, 0, -4, -17, -4]],
+  ["milliseconds", [0, 0, 0, 0, 4, 17, 4, 865], [0, 0, 0, 0, -4, -17, -4, -864]],
+  ["microseconds", [0, 0, 0, 0, 4, 17, 4, 864, 198], [0, 0, 0, 0, -4, -17, -4, -864, -197]],
+  ["nanoseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197, 500], [0, 0, 0, 0, -4, -17, -4, -864, -197, -500]],
+];
+
+const roundingMode = "ceil";
+
+expected.forEach(([smallestUnit, expectedPositive, expectedNegative]) => {
+  const [py, pm = 0, pw = 0, pd = 0, ph = 0, pmin = 0, ps = 0, pms = 0, pµs = 0, pns = 0] = expectedPositive;
+  const [ny, nm = 0, nw = 0, nd = 0, nh = 0, nmin = 0, ns = 0, nms = 0, nµs = 0, nns = 0] = expectedNegative;
+  TemporalHelpers.assertDuration(
+    later.since(earlier, { smallestUnit, roundingMode }),
+    py, pm, pw, pd, ph, pmin, ps, pms, pµs, pns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode}, positive case)`
+  );
+  TemporalHelpers.assertDuration(
+    earlier.since(later, { smallestUnit, roundingMode }),
+    ny, nm, nw, nd, nh, nmin, ns, nms, nµs, nns,
+    `rounds to ${smallestUnit} (rounding mode = ${roundingMode}, negative case)`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-expand.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-expand.js
new file mode 100644
index 0000000000..054ceaca29
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-expand.js
@@ -0,0 +1,41 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Tests calculations with roundingMode "expand".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(8, 22, 36, 123, 456, 789);
+const later = new Temporal.PlainTime(12, 39, 40, 987, 654, 289);
+
+const expected = [
+  ["hours", [0, 0, 0, 0, 5], [0, 0, 0, 0, -5]],
+  ["minutes", [0, 0, 0, 0, 4, 18], [0, 0, 0, 0, -4, -18]],
+  ["seconds", [0, 0, 0, 0, 4, 17, 5], [0, 0, 0, 0, -4, -17, -5]],
+  ["milliseconds", [0, 0, 0, 0, 4, 17, 4, 865], [0, 0, 0, 0, -4, -17, -4, -865]],
+  ["microseconds", [0, 0, 0, 0, 4, 17, 4, 864, 198], [0, 0, 0, 0, -4, -17, -4, -864, -198]],
+  ["nanoseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197, 500], [0, 0, 0, 0, -4, -17, -4, -864, -197, -500]],
+];
+
+const roundingMode = "expand";
+
+expected.forEach(([smallestUnit, expectedPositive, expectedNegative]) => {
+  const [py, pm = 0, pw = 0, pd = 0, ph = 0, pmin = 0, ps = 0, pms = 0, pµs = 0, pns = 0] = expectedPositive;
+  const [ny, nm = 0, nw = 0, nd = 0, nh = 0, nmin = 0, ns = 0, nms = 0, nµs = 0, nns = 0] = expectedNegative;
+  TemporalHelpers.assertDuration(
+    later.since(earlier, { smallestUnit, roundingMode }),
+    py, pm, pw, pd, ph, pmin, ps, pms, pµs, pns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode}, positive case)`
+  );
+  TemporalHelpers.assertDuration(
+    earlier.since(later, { smallestUnit, roundingMode }),
+    ny, nm, nw, nd, nh, nmin, ns, nms, nµs, nns,
+    `rounds to ${smallestUnit} (rounding mode = ${roundingMode}, negative case)`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-floor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-floor.js
new file mode 100644
index 0000000000..719f9e4d8b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-floor.js
@@ -0,0 +1,41 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Tests calculations with roundingMode "floor".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(8, 22, 36, 123, 456, 789);
+const later = new Temporal.PlainTime(12, 39, 40, 987, 654, 289);
+
+const expected = [
+  ["hours", [0, 0, 0, 0, 4], [0, 0, 0, 0, -5]],
+  ["minutes", [0, 0, 0, 0, 4, 17], [0, 0, 0, 0, -4, -18]],
+  ["seconds", [0, 0, 0, 0, 4, 17, 4], [0, 0, 0, 0, -4, -17, -5]],
+  ["milliseconds", [0, 0, 0, 0, 4, 17, 4, 864], [0, 0, 0, 0, -4, -17, -4, -865]],
+  ["microseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197], [0, 0, 0, 0, -4, -17, -4, -864, -198]],
+  ["nanoseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197, 500], [0, 0, 0, 0, -4, -17, -4, -864, -197, -500]],
+];
+
+const roundingMode = "floor";
+
+expected.forEach(([smallestUnit, expectedPositive, expectedNegative]) => {
+  const [py, pm = 0, pw = 0, pd = 0, ph = 0, pmin = 0, ps = 0, pms = 0, pµs = 0, pns = 0] = expectedPositive;
+  const [ny, nm = 0, nw = 0, nd = 0, nh = 0, nmin = 0, ns = 0, nms = 0, nµs = 0, nns = 0] = expectedNegative;
+  TemporalHelpers.assertDuration(
+    later.since(earlier, { smallestUnit, roundingMode }),
+    py, pm, pw, pd, ph, pmin, ps, pms, pµs, pns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode}, positive case)`
+  );
+  TemporalHelpers.assertDuration(
+    earlier.since(later, { smallestUnit, roundingMode }),
+    ny, nm, nw, nd, nh, nmin, ns, nms, nµs, nns,
+    `rounds to ${smallestUnit} (rounding mode = ${roundingMode}, negative case)`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-halfCeil.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-halfCeil.js
new file mode 100644
index 0000000000..d9e41261b1
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-halfCeil.js
@@ -0,0 +1,41 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Tests calculations with roundingMode "halfCeil".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(8, 22, 36, 123, 456, 789);
+const later = new Temporal.PlainTime(12, 39, 40, 987, 654, 289);
+
+const expected = [
+  ["hours", [0, 0, 0, 0, 4], [0, 0, 0, 0, -4]],
+  ["minutes", [0, 0, 0, 0, 4, 17], [0, 0, 0, 0, -4, -17]],
+  ["seconds", [0, 0, 0, 0, 4, 17, 5], [0, 0, 0, 0, -4, -17, -5]],
+  ["milliseconds", [0, 0, 0, 0, 4, 17, 4, 864], [0, 0, 0, 0, -4, -17, -4, -864]],
+  ["microseconds", [0, 0, 0, 0, 4, 17, 4, 864, 198], [0, 0, 0, 0, -4, -17, -4, -864, -197]],
+  ["nanoseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197, 500], [0, 0, 0, 0, -4, -17, -4, -864, -197, -500]],
+];
+
+const roundingMode = "halfCeil";
+
+expected.forEach(([smallestUnit, expectedPositive, expectedNegative]) => {
+  const [py, pm = 0, pw = 0, pd = 0, ph = 0, pmin = 0, ps = 0, pms = 0, pµs = 0, pns = 0] = expectedPositive;
+  const [ny, nm = 0, nw = 0, nd = 0, nh = 0, nmin = 0, ns = 0, nms = 0, nµs = 0, nns = 0] = expectedNegative;
+  TemporalHelpers.assertDuration(
+    later.since(earlier, { smallestUnit, roundingMode }),
+    py, pm, pw, pd, ph, pmin, ps, pms, pµs, pns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode}, positive case)`
+  );
+  TemporalHelpers.assertDuration(
+    earlier.since(later, { smallestUnit, roundingMode }),
+    ny, nm, nw, nd, nh, nmin, ns, nms, nµs, nns,
+    `rounds to ${smallestUnit} (rounding mode = ${roundingMode}, negative case)`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-halfEven.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-halfEven.js
new file mode 100644
index 0000000000..6be4bcd784
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-halfEven.js
@@ -0,0 +1,41 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Tests calculations with roundingMode "halfEven".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(8, 22, 36, 123, 456, 789);
+const later = new Temporal.PlainTime(12, 39, 40, 987, 654, 289);
+
+const expected = [
+  ["hours", [0, 0, 0, 0, 4], [0, 0, 0, 0, -4]],
+  ["minutes", [0, 0, 0, 0, 4, 17], [0, 0, 0, 0, -4, -17]],
+  ["seconds", [0, 0, 0, 0, 4, 17, 5], [0, 0, 0, 0, -4, -17, -5]],
+  ["milliseconds", [0, 0, 0, 0, 4, 17, 4, 864], [0, 0, 0, 0, -4, -17, -4, -864]],
+  ["microseconds", [0, 0, 0, 0, 4, 17, 4, 864, 198], [0, 0, 0, 0, -4, -17, -4, -864, -198]],
+  ["nanoseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197, 500], [0, 0, 0, 0, -4, -17, -4, -864, -197, -500]],
+];
+
+const roundingMode = "halfEven";
+
+expected.forEach(([smallestUnit, expectedPositive, expectedNegative]) => {
+  const [py, pm = 0, pw = 0, pd = 0, ph = 0, pmin = 0, ps = 0, pms = 0, pµs = 0, pns = 0] = expectedPositive;
+  const [ny, nm = 0, nw = 0, nd = 0, nh = 0, nmin = 0, ns = 0, nms = 0, nµs = 0, nns = 0] = expectedNegative;
+  TemporalHelpers.assertDuration(
+    later.since(earlier, { smallestUnit, roundingMode }),
+    py, pm, pw, pd, ph, pmin, ps, pms, pµs, pns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode}, positive case)`
+  );
+  TemporalHelpers.assertDuration(
+    earlier.since(later, { smallestUnit, roundingMode }),
+    ny, nm, nw, nd, nh, nmin, ns, nms, nµs, nns,
+    `rounds to ${smallestUnit} (rounding mode = ${roundingMode}, negative case)`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-halfExpand.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-halfExpand.js
new file mode 100644
index 0000000000..cd42d2e0d0
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-halfExpand.js
@@ -0,0 +1,41 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Tests calculations with roundingMode "halfExpand".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(8, 22, 36, 123, 456, 789);
+const later = new Temporal.PlainTime(12, 39, 40, 987, 654, 289);
+
+const expected = [
+  ["hours", [0, 0, 0, 0, 4], [0, 0, 0, 0, -4]],
+  ["minutes", [0, 0, 0, 0, 4, 17], [0, 0, 0, 0, -4, -17]],
+  ["seconds", [0, 0, 0, 0, 4, 17, 5], [0, 0, 0, 0, -4, -17, -5]],
+  ["milliseconds", [0, 0, 0, 0, 4, 17, 4, 864], [0, 0, 0, 0, -4, -17, -4, -864]],
+  ["microseconds", [0, 0, 0, 0, 4, 17, 4, 864, 198], [0, 0, 0, 0, -4, -17, -4, -864, -198]],
+  ["nanoseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197, 500], [0, 0, 0, 0, -4, -17, -4, -864, -197, -500]],
+];
+
+const roundingMode = "halfExpand";
+
+expected.forEach(([smallestUnit, expectedPositive, expectedNegative]) => {
+  const [py, pm = 0, pw = 0, pd = 0, ph = 0, pmin = 0, ps = 0, pms = 0, pµs = 0, pns = 0] = expectedPositive;
+  const [ny, nm = 0, nw = 0, nd = 0, nh = 0, nmin = 0, ns = 0, nms = 0, nµs = 0, nns = 0] = expectedNegative;
+  TemporalHelpers.assertDuration(
+    later.since(earlier, { smallestUnit, roundingMode }),
+    py, pm, pw, pd, ph, pmin, ps, pms, pµs, pns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode}, positive case)`
+  );
+  TemporalHelpers.assertDuration(
+    earlier.since(later, { smallestUnit, roundingMode }),
+    ny, nm, nw, nd, nh, nmin, ns, nms, nµs, nns,
+    `rounds to ${smallestUnit} (rounding mode = ${roundingMode}, negative case)`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-halfFloor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-halfFloor.js
new file mode 100644
index 0000000000..6bd323aa61
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-halfFloor.js
@@ -0,0 +1,41 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Tests calculations with roundingMode "halfFloor".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(8, 22, 36, 123, 456, 789);
+const later = new Temporal.PlainTime(12, 39, 40, 987, 654, 289);
+
+const expected = [
+  ["hours", [0, 0, 0, 0, 4], [0, 0, 0, 0, -4]],
+  ["minutes", [0, 0, 0, 0, 4, 17], [0, 0, 0, 0, -4, -17]],
+  ["seconds", [0, 0, 0, 0, 4, 17, 5], [0, 0, 0, 0, -4, -17, -5]],
+  ["milliseconds", [0, 0, 0, 0, 4, 17, 4, 864], [0, 0, 0, 0, -4, -17, -4, -864]],
+  ["microseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197], [0, 0, 0, 0, -4, -17, -4, -864, -198]],
+  ["nanoseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197, 500], [0, 0, 0, 0, -4, -17, -4, -864, -197, -500]],
+];
+
+const roundingMode = "halfFloor";
+
+expected.forEach(([smallestUnit, expectedPositive, expectedNegative]) => {
+  const [py, pm = 0, pw = 0, pd = 0, ph = 0, pmin = 0, ps = 0, pms = 0, pµs = 0, pns = 0] = expectedPositive;
+  const [ny, nm = 0, nw = 0, nd = 0, nh = 0, nmin = 0, ns = 0, nms = 0, nµs = 0, nns = 0] = expectedNegative;
+  TemporalHelpers.assertDuration(
+    later.since(earlier, { smallestUnit, roundingMode }),
+    py, pm, pw, pd, ph, pmin, ps, pms, pµs, pns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode}, positive case)`
+  );
+  TemporalHelpers.assertDuration(
+    earlier.since(later, { smallestUnit, roundingMode }),
+    ny, nm, nw, nd, nh, nmin, ns, nms, nµs, nns,
+    `rounds to ${smallestUnit} (rounding mode = ${roundingMode}, negative case)`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-halfTrunc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-halfTrunc.js
new file mode 100644
index 0000000000..3b2b0a5bbc
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-halfTrunc.js
@@ -0,0 +1,41 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Tests calculations with roundingMode "halfTrunc".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(8, 22, 36, 123, 456, 789);
+const later = new Temporal.PlainTime(12, 39, 40, 987, 654, 289);
+
+const expected = [
+  ["hours", [0, 0, 0, 0, 4], [0, 0, 0, 0, -4]],
+  ["minutes", [0, 0, 0, 0, 4, 17], [0, 0, 0, 0, -4, -17]],
+  ["seconds", [0, 0, 0, 0, 4, 17, 5], [0, 0, 0, 0, -4, -17, -5]],
+  ["milliseconds", [0, 0, 0, 0, 4, 17, 4, 864], [0, 0, 0, 0, -4, -17, -4, -864]],
+  ["microseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197], [0, 0, 0, 0, -4, -17, -4, -864, -197]],
+  ["nanoseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197, 500], [0, 0, 0, 0, -4, -17, -4, -864, -197, -500]],
+];
+
+const roundingMode = "halfTrunc";
+
+expected.forEach(([smallestUnit, expectedPositive, expectedNegative]) => {
+  const [py, pm = 0, pw = 0, pd = 0, ph = 0, pmin = 0, ps = 0, pms = 0, pµs = 0, pns = 0] = expectedPositive;
+  const [ny, nm = 0, nw = 0, nd = 0, nh = 0, nmin = 0, ns = 0, nms = 0, nµs = 0, nns = 0] = expectedNegative;
+  TemporalHelpers.assertDuration(
+    later.since(earlier, { smallestUnit, roundingMode }),
+    py, pm, pw, pd, ph, pmin, ps, pms, pµs, pns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode}, positive case)`
+  );
+  TemporalHelpers.assertDuration(
+    earlier.since(later, { smallestUnit, roundingMode }),
+    ny, nm, nw, nd, nh, nmin, ns, nms, nµs, nns,
+    `rounds to ${smallestUnit} (rounding mode = ${roundingMode}, negative case)`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-invalid-string.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-invalid-string.js
new file mode 100644
index 0000000000..df81559e41
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-invalid-string.js
@@ -0,0 +1,17 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: RangeError thrown when roundingMode option not one of the allowed string values
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 0, 0, 0);
+const later = new Temporal.PlainTime(13, 35, 57, 123, 987, 500);
+for (const roundingMode of ["other string", "cile", "CEIL", "ce\u0131l", "auto", "halfexpand", "floor\0"]) {
+  assert.throws(RangeError, () => later.since(earlier, { smallestUnit: "microsecond", roundingMode }));
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-trunc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-trunc.js
new file mode 100644
index 0000000000..ccfe498cb4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-trunc.js
@@ -0,0 +1,41 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Tests calculations with roundingMode "trunc".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(8, 22, 36, 123, 456, 789);
+const later = new Temporal.PlainTime(12, 39, 40, 987, 654, 289);
+
+const expected = [
+  ["hours", [0, 0, 0, 0, 4], [0, 0, 0, 0, -4]],
+  ["minutes", [0, 0, 0, 0, 4, 17], [0, 0, 0, 0, -4, -17]],
+  ["seconds", [0, 0, 0, 0, 4, 17, 4], [0, 0, 0, 0, -4, -17, -4]],
+  ["milliseconds", [0, 0, 0, 0, 4, 17, 4, 864], [0, 0, 0, 0, -4, -17, -4, -864]],
+  ["microseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197], [0, 0, 0, 0, -4, -17, -4, -864, -197]],
+  ["nanoseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197, 500], [0, 0, 0, 0, -4, -17, -4, -864, -197, -500]],
+];
+
+const roundingMode = "trunc";
+
+expected.forEach(([smallestUnit, expectedPositive, expectedNegative]) => {
+  const [py, pm = 0, pw = 0, pd = 0, ph = 0, pmin = 0, ps = 0, pms = 0, pµs = 0, pns = 0] = expectedPositive;
+  const [ny, nm = 0, nw = 0, nd = 0, nh = 0, nmin = 0, ns = 0, nms = 0, nµs = 0, nns = 0] = expectedNegative;
+  TemporalHelpers.assertDuration(
+    later.since(earlier, { smallestUnit, roundingMode }),
+    py, pm, pw, pd, ph, pmin, ps, pms, pµs, pns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode}, positive case)`
+  );
+  TemporalHelpers.assertDuration(
+    earlier.since(later, { smallestUnit, roundingMode }),
+    ny, nm, nw, nd, nh, nmin, ns, nms, nµs, nns,
+    `rounds to ${smallestUnit} (rounding mode = ${roundingMode}, negative case)`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-undefined.js
new file mode 100644
index 0000000000..12148d8a52
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-undefined.js
@@ -0,0 +1,93 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Fallback value for roundingMode option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = Temporal.PlainTime.from("08:22:36.123456789");
+const later = Temporal.PlainTime.from("12:39:40.987654321");
+
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "hours", roundingMode: undefined }),
+  0, 0, 0, 0, 4, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "hours" }),
+  0, 0, 0, 0, 4, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertDuration(
+  earlier.since(later, { smallestUnit: "hours", roundingMode: undefined }),
+  0, 0, 0, 0, -4, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertDuration(
+  earlier.since(later, { smallestUnit: "hours" }),
+  0, 0, 0, 0, -4, 0, 0, 0, 0, 0, "hours");
+
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "minutes", roundingMode: undefined }),
+  0, 0, 0, 0, 4, 17, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "minutes" }),
+  0, 0, 0, 0, 4, 17, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  earlier.since(later, { smallestUnit: "minutes", roundingMode: undefined }),
+  0, 0, 0, 0, -4, -17, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  earlier.since(later, { smallestUnit: "minutes" }),
+  0, 0, 0, 0, -4, -17, 0, 0, 0, 0, "minutes");
+
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "seconds", roundingMode: undefined }),
+  0, 0, 0, 0, 4, 17, 4, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "seconds" }),
+  0, 0, 0, 0, 4, 17, 4, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  earlier.since(later, { smallestUnit: "seconds", roundingMode: undefined }),
+  0, 0, 0, 0, -4, -17, -4, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  earlier.since(later, { smallestUnit: "seconds" }),
+  0, 0, 0, 0, -4, -17, -4, 0, 0, 0, "seconds");
+
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "milliseconds", roundingMode: undefined }),
+  0, 0, 0, 0, 4, 17, 4, 864, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "milliseconds" }),
+  0, 0, 0, 0, 4, 17, 4, 864, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  earlier.since(later, { smallestUnit: "milliseconds", roundingMode: undefined }),
+  0, 0, 0, 0, -4, -17, -4, -864, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  earlier.since(later, { smallestUnit: "milliseconds" }),
+  0, 0, 0, 0, -4, -17, -4, -864, 0, 0, "milliseconds");
+
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "microseconds", roundingMode: undefined }),
+  0, 0, 0, 0, 4, 17, 4, 864, 197, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "microseconds" }),
+  0, 0, 0, 0, 4, 17, 4, 864, 197, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  earlier.since(later, { smallestUnit: "microseconds", roundingMode: undefined }),
+  0, 0, 0, 0, -4, -17, -4, -864, -197, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  earlier.since(later, { smallestUnit: "microseconds" }),
+  0, 0, 0, 0, -4, -17, -4, -864, -197, 0, "microseconds");
+
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "nanoseconds", roundingMode: undefined }),
+  0, 0, 0, 0, 4, 17, 4, 864, 197, 532, "nanoseconds");
+TemporalHelpers.assertDuration(
+  later.since(earlier, { smallestUnit: "nanoseconds" }),
+  0, 0, 0, 0, 4, 17, 4, 864, 197, 532, "nanoseconds");
+TemporalHelpers.assertDuration(
+  earlier.since(later, { smallestUnit: "nanoseconds", roundingMode: undefined }),
+  0, 0, 0, 0, -4, -17, -4, -864, -197, -532, "nanoseconds");
+TemporalHelpers.assertDuration(
+  earlier.since(later, { smallestUnit: "nanoseconds" }),
+  0, 0, 0, 0, -4, -17, -4, -864, -197, -532, "nanoseconds");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-wrong-type.js
new file mode 100644
index 0000000000..3c55d28bc4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/roundingmode-wrong-type.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Type conversions for roundingMode option
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 0, 0, 0);
+const later = new Temporal.PlainTime(13, 35, 57, 123, 987, 500);
+TemporalHelpers.checkStringOptionWrongType("roundingMode", "trunc",
+  (roundingMode) => later.since(earlier, { smallestUnit: "microsecond", roundingMode }),
+  (result, descr) => TemporalHelpers.assertDuration(result, 0, 0, 0, 0, 1, 1, 1, 123, 987, 0, descr),
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/smallestunit-invalid-string.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/smallestunit-invalid-string.js
new file mode 100644
index 0000000000..72fe195582
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/smallestunit-invalid-string.js
@@ -0,0 +1,39 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: RangeError thrown when smallestUnit option not one of the allowed string values
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 0, 0, 0);
+const later = new Temporal.PlainTime(13, 35, 57, 987, 654, 321);
+const badValues = [
+  "era",
+  "eraYear",
+  "year",
+  "month",
+  "week",
+  "day",
+  "millisecond\0",
+  "mill\u0131second",
+  "SECOND",
+  "eras",
+  "eraYears",
+  "years",
+  "months",
+  "weeks",
+  "days",
+  "milliseconds\0",
+  "mill\u0131seconds",
+  "SECONDS",
+  "other string",
+];
+for (const smallestUnit of badValues) {
+  assert.throws(RangeError, () => later.since(earlier, { smallestUnit }),
+    `"${smallestUnit}" is not a valid value for smallest unit`);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/smallestunit-plurals-accepted.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/smallestunit-plurals-accepted.js
new file mode 100644
index 0000000000..7d346ef74d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/smallestunit-plurals-accepted.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Plural units are accepted as well for the smallestUnit option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+const later = new Temporal.PlainTime(13, 35, 57, 988, 655, 322);
+const validUnits = [
+  "hour",
+  "minute",
+  "second",
+  "millisecond",
+  "microsecond",
+  "nanosecond",
+];
+TemporalHelpers.checkPluralUnitsAccepted((smallestUnit) => later.since(earlier, { smallestUnit }), validUnits);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/smallestunit-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/smallestunit-undefined.js
new file mode 100644
index 0000000000..f5095ffddf
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/smallestunit-undefined.js
@@ -0,0 +1,22 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Fallback value for smallestUnit option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 0, 0, 0);
+const later = new Temporal.PlainTime(13, 35, 57, 987, 654, 321);
+
+const explicit = later.since(earlier, { smallestUnit: undefined });
+TemporalHelpers.assertDuration(explicit, 0, 0, 0, 0, 1, 1, 1, 987, 654, 321, "default smallestUnit is nanosecond");
+const implicit = later.since(earlier, {});
+TemporalHelpers.assertDuration(implicit, 0, 0, 0, 0, 1, 1, 1, 987, 654, 321, "default smallestUnit is nanosecond");
+const lambda = later.since(earlier, () => {});
+TemporalHelpers.assertDuration(lambda, 0, 0, 0, 0, 1, 1, 1, 987, 654, 321, "default smallestUnit is nanosecond");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/smallestunit-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/smallestunit-wrong-type.js
new file mode 100644
index 0000000000..9ad7752909
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/smallestunit-wrong-type.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Type conversions for smallestUnit option
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 0, 0, 0);
+const later = new Temporal.PlainTime(13, 35, 57, 987, 654, 321);
+TemporalHelpers.checkStringOptionWrongType("smallestUnit", "microsecond",
+  (smallestUnit) => later.since(earlier, { smallestUnit }),
+  (result, descr) => TemporalHelpers.assertDuration(result, 0, 0, 0, 0, 1, 1, 1, 987, 654, 0, descr),
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/year-zero.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/year-zero.js
new file mode 100644
index 0000000000..86ea5422c8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/since/year-zero.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Negative zero, as an extended year, is rejected
+features: [Temporal, arrow-function]
+---*/
+
+const invalidStrings = [
+  "-000000-12-07T03:24:30",
+  "-000000-12-07T03:24:30+01:00",
+  "-000000-12-07T03:24:30+00:00[UTC]",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => instance.since(arg),
+    "reject minus zero as extended year"
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-duration.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-duration.js
new file mode 100644
index 0000000000..d8b5bd7a94
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-duration.js
@@ -0,0 +1,17 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: Duration arguments are supported.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const plainTime = new Temporal.PlainTime(15, 23, 30, 123, 456, 789);
+const duration = Temporal.Duration.from("PT16H");
+TemporalHelpers.assertPlainTime(plainTime.subtract(duration),
+  23, 23, 30, 123, 456, 789);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-higher-units.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-higher-units.js
new file mode 100644
index 0000000000..8b42d39033
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-higher-units.js
@@ -0,0 +1,32 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: Higher units are ignored.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const plainTime = new Temporal.PlainTime(15, 23, 30, 123, 456, 789);
+const values = [
+  new Temporal.Duration(0, 0, 0, 1),
+  new Temporal.Duration(0, 0, 1),
+  new Temporal.Duration(0, 1),
+  new Temporal.Duration(1),
+  { days: 1 },
+  { weeks: 1 },
+  { months: 1 },
+  { years: 1 },
+  "P1D",
+  "P1W",
+  "P1M",
+  "P1Y",
+];
+for (const value of values) {
+  TemporalHelpers.assertPlainTime(plainTime.subtract(value),
+    15, 23, 30, 123, 456, 789);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-invalid-property.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-invalid-property.js
new file mode 100644
index 0000000000..d30afc2458
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-invalid-property.js
@@ -0,0 +1,31 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: temporalDurationLike object must contain at least one correctly spelled property
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(15, 30, 45, 987, 654, 321);
+
+assert.throws(
+  TypeError,
+  () => instance.subtract({}),
+  "Throws TypeError if no property is present"
+);
+
+assert.throws(
+  TypeError,
+  () => instance.subtract({ nonsense: true }),
+  "Throws TypeError if no recognized property is present"
+);
+
+assert.throws(
+  TypeError,
+  () => instance.subtract({ sign: 1 }),
+  "Sign property is not recognized"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-mixed-sign.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-mixed-sign.js
new file mode 100644
index 0000000000..2e59e15ca4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-mixed-sign.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: Positive and negative values in the temporalDurationLike argument are not acceptable
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(15, 30, 45, 987, 654, 321);
+
+assert.throws(
+  RangeError,
+  () => instance.subtract({ hours: 1, minutes: -30 }),
+  `mixed positive and negative values always throw`
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-not-object.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-not-object.js
new file mode 100644
index 0000000000..6a4f5183a0
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-not-object.js
@@ -0,0 +1,22 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: Passing a primitive other than string to subtract() throws
+features: [Symbol, Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(15, 30, 45, 987, 654, 321);
+assert.throws(RangeError, () => instance.subtract(undefined), "undefined");
+assert.throws(RangeError, () => instance.subtract(null), "null");
+assert.throws(RangeError, () => instance.subtract(true), "boolean");
+assert.throws(RangeError, () => instance.subtract(""), "empty string");
+assert.throws(TypeError, () => instance.subtract(Symbol()), "Symbol");
+assert.throws(RangeError, () => instance.subtract(7), "number");
+assert.throws(RangeError, () => instance.subtract(7n), "bigint");
+assert.throws(TypeError, () => instance.subtract([]), "array");
+assert.throws(TypeError, () => instance.subtract(() => {}), "function");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-object.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-object.js
new file mode 100644
index 0000000000..49bba444cd
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-object.js
@@ -0,0 +1,40 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: Plain object arguments are supported.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const plainTime = new Temporal.PlainTime(15, 23, 30, 123, 456, 789);
+TemporalHelpers.assertPlainTime(plainTime.subtract({ hours: 16 }),
+  23, 23, 30, 123, 456, 789, "subtract 16 hours across midnight boundary");
+TemporalHelpers.assertPlainTime(plainTime.subtract({ minutes: 45 }),
+  14, 38, 30, 123, 456, 789, "subtract 45 minutes");
+TemporalHelpers.assertPlainTime(plainTime.subtract({ seconds: 45 }),
+  15, 22, 45, 123, 456, 789, "subtract 45 seconds");
+TemporalHelpers.assertPlainTime(plainTime.subtract({ milliseconds: 800 }),
+  15, 23, 29, 323, 456, 789, "subtract 800 milliseconds");
+TemporalHelpers.assertPlainTime(plainTime.subtract({ microseconds: 800 }),
+  15, 23, 30, 122, 656, 789, "subtract 800 microseconds");
+TemporalHelpers.assertPlainTime(plainTime.subtract({ nanoseconds: 800 }),
+  15, 23, 30, 123, 455, 989, "subtract 800 nanoseconds");
+TemporalHelpers.assertPlainTime(Temporal.PlainTime.from("23:23:30.123456789").subtract({ hours: -16 }),
+  15, 23, 30, 123, 456, 789, "subtract -16 hours across midnight boundary");
+TemporalHelpers.assertPlainTime(Temporal.PlainTime.from("14:38:30.123456789").subtract({ minutes: -45 }),
+  15, 23, 30, 123, 456, 789, "subtract -45 minutes");
+TemporalHelpers.assertPlainTime(Temporal.PlainTime.from("15:22:45.123456789").subtract({ seconds: -45 }),
+  15, 23, 30, 123, 456, 789, "subtract -45 seconds");
+TemporalHelpers.assertPlainTime(Temporal.PlainTime.from("15:23:29.323456789").subtract({ milliseconds: -800 }),
+  15, 23, 30, 123, 456, 789, "subtract -800 milliseconds");
+TemporalHelpers.assertPlainTime(Temporal.PlainTime.from("15:23:30.122656789").subtract({ microseconds: -800 }),
+  15, 23, 30, 123, 456, 789, "subtract -800 microseconds");
+TemporalHelpers.assertPlainTime(Temporal.PlainTime.from("15:23:30.123455989").subtract({ nanoseconds: -800 }),
+  15, 23, 30, 123, 456, 789, "subtract -800 nanoseconds");
+TemporalHelpers.assertPlainTime(plainTime.subtract({ minute: 1, hours: 1 }),
+  14, 23, 30, 123, 456, 789, "misspelled property is ignored");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-singular-properties.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-singular-properties.js
new file mode 100644
index 0000000000..9ea8dd3632
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-singular-properties.js
@@ -0,0 +1,30 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: Singular properties in the property bag are always ignored
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(15, 30, 45, 987, 654, 321);
+
+[
+  { year: 1 },
+  { month: 2 },
+  { week: 3 },
+  { day: 4 },
+  { hour: 5 },
+  { minute: 6 },
+  { second: 7 },
+  { millisecond: 8 },
+  { microsecond: 9 },
+  { nanosecond: 10 },
+].forEach((badObject) => {
+  assert.throws(TypeError, () => instance.subtract(badObject),
+    "Throw TypeError if temporalDurationLike is not valid");
+});
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-string-duration-too-large.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-string-duration-too-large.js
new file mode 100644
index 0000000000..03a1bc47e2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-string-duration-too-large.js
@@ -0,0 +1,21 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: >
+  ParseTemporalDurationString throws a RangeError when the result is too large.
+features: [Temporal]
+---*/
+
+// Number string too long to be representable as a Number value.
+var ones = "1".repeat(1000);
+assert.sameValue(Number(ones), Infinity);
+
+var time = new Temporal.PlainTime();
+var str = "PT" + ones + "S";
+
+assert.throws(RangeError, () => time.subtract(str));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-string-fractional-units-rounding-mode.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-string-fractional-units-rounding-mode.js
new file mode 100644
index 0000000000..f1ce3233a6
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-string-fractional-units-rounding-mode.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: Strings with fractional duration units are rounded with the correct rounding mode
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const midnight = new Temporal.PlainTime();
+
+TemporalHelpers.assertPlainTime(midnight.subtract("PT1.03125H"), 22, 58, 7, 500, 0, 0,
+  "positive fractional units rounded with correct rounding mode");
+TemporalHelpers.assertPlainTime(midnight.subtract("-PT1.03125H"), 1, 1, 52, 500, 0, 0,
+  "negative fractional units rounded with correct rounding mode");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-string-negative-fractional-units.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-string-negative-fractional-units.js
new file mode 100644
index 0000000000..5fe15bccba
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-string-negative-fractional-units.js
@@ -0,0 +1,20 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: Strings with fractional duration units are treated with the correct sign
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime();
+
+const resultHours = instance.subtract("-PT24.567890123H");
+TemporalHelpers.assertPlainTime(resultHours, 0, 34, 4, 404, 442, 800, "negative fractional hours");
+
+const resultMinutes = instance.subtract("-PT1440.567890123M");
+TemporalHelpers.assertPlainTime(resultMinutes, 0, 0, 34, 73, 407, 380, "negative fractional minutes");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-string.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-string.js
new file mode 100644
index 0000000000..62ddb4c104
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/argument-string.js
@@ -0,0 +1,16 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: A string is parsed into the correct object when passed as the argument
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = Temporal.PlainTime.from({ hour: 12, minute: 34, second: 56, millisecond: 987, microsecond: 654, nanosecond: 321 });
+const result = instance.subtract("PT3M");
+TemporalHelpers.assertPlainTime(result, 12, 31, 56, 987, 654, 321);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/balance-negative-time-units.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/balance-negative-time-units.js
new file mode 100644
index 0000000000..1c90b59d0c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/balance-negative-time-units.js
@@ -0,0 +1,50 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: Negative time fields are balanced upwards
+info: |
+    sec-temporal-balancetime steps 3–14:
+      3. Set _microsecond_ to _microsecond_ + floor(_nanosecond_ / 1000).
+      4. Set _nanosecond_ to _nanosecond_ modulo 1000.
+      5. Set _millisecond_ to _millisecond_ + floor(_microsecond_ / 1000).
+      6. Set _microsecond_ to _microsecond_ modulo 1000.
+      7. Set _second_ to _second_ + floor(_millisecond_ / 1000).
+      8. Set _millisecond_ to _millisecond_ modulo 1000.
+      9. Set _minute_ to _minute_ + floor(_second_ / 60).
+      10. Set _second_ to _second_ modulo 60.
+      11. Set _hour_ to _hour_ + floor(_minute_ / 60).
+      12. Set _minute_ to _minute_ modulo 60.
+      13. Let _days_ be floor(_hour_ / 24).
+      14. Set _hour_ to _hour_ modulo 24.
+    sec-temporal-addtime step 8:
+      8. Return ? BalanceTime(_hour_, _minute_, _second_, _millisecond_, _microsecond_, _nanosecond_).
+    sec-temporal.plaintime.prototype.subtract step 4:
+      4. Let _result_ be ? AddTime(_temporalTime_.[[ISOHour]], _temporalTime_.[[ISOMinute]], _temporalTime_.[[ISOSecond]], _temporalTime_.[[ISOMillisecond]], _temporalTime_.[[ISOMicrosecond]], _temporalTime_.[[ISONanosecond]], −_duration_.[[Hours]], −_duration_.[[Minutes]], −_duration_.[[Seconds]], −_duration_.[[Milliseconds]], −_duration_.[[Microseconds]], −_duration_.[[Nanoseconds]]).
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(1, 1, 1, 1, 1, 1);
+
+const result1 = time.subtract(new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 0, 2));
+TemporalHelpers.assertPlainTime(result1, 1, 1, 1, 1, 0, 999, "nanoseconds balance");
+
+const result2 = time.subtract(new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 2));
+TemporalHelpers.assertPlainTime(result2, 1, 1, 1, 0, 999, 1, "microseconds balance");
+
+const result3 = time.subtract(new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 2));
+TemporalHelpers.assertPlainTime(result3, 1, 1, 0, 999, 1, 1, "milliseconds balance");
+
+const result4 = time.subtract(new Temporal.Duration(0, 0, 0, 0, 0, 0, 2));
+TemporalHelpers.assertPlainTime(result4, 1, 0, 59, 1, 1, 1, "seconds balance");
+
+const result5 = time.subtract(new Temporal.Duration(0, 0, 0, 0, 0, 2));
+TemporalHelpers.assertPlainTime(result5, 0, 59, 1, 1, 1, 1, "minutes balance");
+
+const result6 = time.subtract(new Temporal.Duration(0, 0, 0, 0, 2));
+TemporalHelpers.assertPlainTime(result6, 23, 1, 1, 1, 1, 1, "hours mod 24");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/branding.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/branding.js
new file mode 100644
index 0000000000..51d90afd54
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/branding.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: Throw a TypeError if the receiver is invalid
+features: [Symbol, Temporal]
+---*/
+
+const subtract = Temporal.PlainTime.prototype.subtract;
+
+assert.sameValue(typeof subtract, "function");
+
+const args = [new Temporal.Duration(0, 0, 0, 0, 5)];
+
+assert.throws(TypeError, () => subtract.apply(undefined, args), "undefined");
+assert.throws(TypeError, () => subtract.apply(null, args), "null");
+assert.throws(TypeError, () => subtract.apply(true, args), "true");
+assert.throws(TypeError, () => subtract.apply("", args), "empty string");
+assert.throws(TypeError, () => subtract.apply(Symbol(), args), "symbol");
+assert.throws(TypeError, () => subtract.apply(1, args), "1");
+assert.throws(TypeError, () => subtract.apply({}, args), "plain object");
+assert.throws(TypeError, () => subtract.apply(Temporal.PlainTime, args), "Temporal.PlainTime");
+assert.throws(TypeError, () => subtract.apply(Temporal.PlainTime.prototype, args), "Temporal.PlainTime.prototype");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/builtin.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/builtin.js
new file mode 100644
index 0000000000..f4a8ed4d0d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/builtin.js
@@ -0,0 +1,36 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: >
+    Tests that Temporal.PlainTime.prototype.subtract
+    meets the requirements for built-in objects defined by the
+    introduction of chapter 17 of the ECMAScript Language Specification.
+info: |
+    Built-in functions that are not constructors do not have a "prototype" property unless
+    otherwise specified in the description of a particular function.
+
+    Unless specified otherwise, a built-in object that is callable as a function is a built-in
+    function object with the characteristics described in 10.3. Unless specified otherwise, the
+    [[Extensible]] internal slot of a built-in object initially has the value true.
+
+    Unless otherwise specified every built-in function and every built-in constructor has the
+    Function prototype object [...] as the value of its [[Prototype]] internal slot.
+features: [Temporal]
+---*/
+
+assert.sameValue(Object.isExtensible(Temporal.PlainTime.prototype.subtract),
+  true, "Built-in objects must be extensible.");
+
+assert.sameValue(Object.prototype.toString.call(Temporal.PlainTime.prototype.subtract),
+  "[object Function]", "Object.prototype.toString");
+
+assert.sameValue(Object.getPrototypeOf(Temporal.PlainTime.prototype.subtract),
+  Function.prototype, "prototype");
+
+assert.sameValue(Temporal.PlainTime.prototype.subtract.hasOwnProperty("prototype"),
+  false, "prototype property");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/infinity-throws-rangeerror.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/infinity-throws-rangeerror.js
new file mode 100644
index 0000000000..9fae515bab
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/infinity-throws-rangeerror.js
@@ -0,0 +1,38 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Temporal.PlainTime.prototype.subtract throws a RangeError if any value in a property bag is Infinity
+esid: sec-temporal.plaintime.prototype.subtract
+features: [Temporal]
+---*/
+
+const overflows = ["constrain", "reject"];
+const fields = ["years", "months", "weeks", "days", "hours", "minutes", "seconds", "milliseconds", "microseconds", "nanoseconds"];
+
+const instance = Temporal.PlainTime.from({ hour: 12, minute: 34, second: 56, millisecond: 987, microsecond: 654, nanosecond: 321 });
+
+overflows.forEach((overflow) => {
+  fields.forEach((field) => {
+    assert.throws(RangeError, () => instance.subtract({ [field]: Infinity }, { overflow }));
+  });
+});
+
+let calls = 0;
+const obj = {
+  valueOf() {
+    calls++;
+    return Infinity;
+  }
+};
+
+overflows.forEach((overflow) => {
+  fields.forEach((field) => {
+    calls = 0;
+    assert.throws(RangeError, () => instance.subtract({ [field]: obj }, { overflow }));
+    assert.sameValue(calls, 1, "it fails after fetching the primitive value");
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/length.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/length.js
new file mode 100644
index 0000000000..6d47aa4721
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/length.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: Temporal.PlainTime.prototype.subtract.length is 1
+info: |
+    Every built-in function object, including constructors, has a "length" property whose value is
+    an integer. Unless otherwise specified, this value is equal to the largest number of named
+    arguments shown in the subclause headings for the function description. Optional parameters
+    (which are indicated with brackets: [ ]) or rest parameters (which are shown using the form
+    «...name») are not included in the default argument count.
+
+    Unless otherwise specified, the "length" property of a built-in function object has the
+    attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.subtract, "length", {
+  value: 1,
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/name.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/name.js
new file mode 100644
index 0000000000..86a3d576eb
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/name.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: Temporal.PlainTime.prototype.subtract.name is "subtract".
+info: |
+    Every built-in function object, including constructors, that is not identified as an anonymous
+    function has a "name" property whose value is a String. Unless otherwise specified, this value
+    is the name that is given to the function in this specification.
+
+    Unless otherwise specified, the "name" property of a built-in function object, if it exists,
+    has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.subtract, "name", {
+  value: "subtract",
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/negative-infinity-throws-rangeerror.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/negative-infinity-throws-rangeerror.js
new file mode 100644
index 0000000000..5e7bc884fb
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/negative-infinity-throws-rangeerror.js
@@ -0,0 +1,38 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Temporal.PlainTime.prototype.subtract throws a RangeError if any value in a property bag is -Infinity
+esid: sec-temporal.plaintime.prototype.subtract
+features: [Temporal]
+---*/
+
+const overflows = ["constrain", "reject"];
+const fields = ["years", "months", "weeks", "days", "hours", "minutes", "seconds", "milliseconds", "microseconds", "nanoseconds"];
+
+const instance = Temporal.PlainTime.from({ hour: 12, minute: 34, second: 56, millisecond: 987, microsecond: 654, nanosecond: 321 });
+
+overflows.forEach((overflow) => {
+  fields.forEach((field) => {
+    assert.throws(RangeError, () => instance.subtract({ [field]: -Infinity }, { overflow }));
+  });
+});
+
+let calls = 0;
+const obj = {
+  valueOf() {
+    calls++;
+    return -Infinity;
+  }
+};
+
+overflows.forEach((overflow) => {
+  fields.forEach((field) => {
+    calls = 0;
+    assert.throws(RangeError, () => instance.subtract({ [field]: obj }, { overflow }));
+    assert.sameValue(calls, 1, "it fails after fetching the primitive value");
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/non-integer-throws-rangeerror.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/non-integer-throws-rangeerror.js
new file mode 100644
index 0000000000..be17682d2c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/non-integer-throws-rangeerror.js
@@ -0,0 +1,29 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: A non-integer value for any recognized property in the property bag, throws a RangeError
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(15, 30, 45, 987, 654, 321);
+const fields = [
+  "years",
+  "months",
+  "weeks",
+  "days",
+  "hours",
+  "minutes",
+  "seconds",
+  "milliseconds",
+  "microseconds",
+  "nanoseconds",
+];
+fields.forEach((field) => {
+  assert.throws(RangeError, () => instance.subtract({ [field]: 1.5 }));
+  assert.throws(RangeError, () => instance.subtract({ [field]: -1.5 }));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/not-a-constructor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/not-a-constructor.js
new file mode 100644
index 0000000000..072da559c4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/not-a-constructor.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: >
+  Temporal.PlainTime.prototype.subtract does not implement [[Construct]], is not new-able
+info: |
+    Built-in function objects that are not identified as constructors do not implement the
+    [[Construct]] internal method unless otherwise specified in the description of a particular
+    function.
+includes: [isConstructor.js]
+features: [Reflect.construct, Temporal]
+---*/
+
+assert.throws(TypeError, () => {
+  new Temporal.PlainTime.prototype.subtract();
+}, "Calling as constructor");
+
+assert.sameValue(isConstructor(Temporal.PlainTime.prototype.subtract), false,
+  "isConstructor(Temporal.PlainTime.prototype.subtract)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/options-ignored.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/options-ignored.js
new file mode 100644
index 0000000000..98590abaee
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/options-ignored.js
@@ -0,0 +1,32 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: Options argument is ignored.
+includes: [temporalHelpers.js]
+features: [Symbol, Temporal]
+---*/
+
+const values = [
+  undefined,
+  null,
+  true,
+  "hello",
+  Symbol("foo"),
+  1,
+  1n,
+  {},
+  () => {},
+  { get overflow() { throw new Test262Error("should not get overflow") } },
+];
+
+const time = Temporal.PlainTime.from("15:23:30.123456789");
+for (const options of values) {
+  TemporalHelpers.assertPlainTime(time.subtract({ hours: 1 }, options),
+    14, 23, 30, 123, 456, 789);
+}
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/order-of-operations.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/order-of-operations.js
new file mode 100644
index 0000000000..c478c130f5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/order-of-operations.js
@@ -0,0 +1,63 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: Properties on an object passed to subtract() are accessed in the correct order
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+const expected = [
+  "get fields.days",
+  "get fields.days.valueOf",
+  "call fields.days.valueOf",
+  "get fields.hours",
+  "get fields.hours.valueOf",
+  "call fields.hours.valueOf",
+  "get fields.microseconds",
+  "get fields.microseconds.valueOf",
+  "call fields.microseconds.valueOf",
+  "get fields.milliseconds",
+  "get fields.milliseconds.valueOf",
+  "call fields.milliseconds.valueOf",
+  "get fields.minutes",
+  "get fields.minutes.valueOf",
+  "call fields.minutes.valueOf",
+  "get fields.months",
+  "get fields.months.valueOf",
+  "call fields.months.valueOf",
+  "get fields.nanoseconds",
+  "get fields.nanoseconds.valueOf",
+  "call fields.nanoseconds.valueOf",
+  "get fields.seconds",
+  "get fields.seconds.valueOf",
+  "call fields.seconds.valueOf",
+  "get fields.weeks",
+  "get fields.weeks.valueOf",
+  "call fields.weeks.valueOf",
+  "get fields.years",
+  "get fields.years.valueOf",
+  "call fields.years.valueOf",
+];
+const actual = [];
+const fields = TemporalHelpers.propertyBagObserver(actual, {
+  years: 1,
+  months: 1,
+  weeks: 1,
+  days: 1,
+  hours: 1,
+  minutes: 1,
+  seconds: 1,
+  milliseconds: 1,
+  microseconds: 1,
+  nanoseconds: 1,
+}, "fields");
+const result = instance.subtract(fields);
+TemporalHelpers.assertPlainTime(result, 11, 33, 55, 986, 653, 320);
+assert.sameValue(result.calendar.id, "iso8601", "calendar result");
+assert.compareArray(actual, expected, "order of operations");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/precision-exact-mathematical-values-1.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/precision-exact-mathematical-values-1.js
new file mode 100644
index 0000000000..2b54de70a0
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/precision-exact-mathematical-values-1.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: >
+  Duration components are precise mathematical integers.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+let duration = Temporal.Duration.from({
+  microseconds: Number.MIN_SAFE_INTEGER,
+  nanoseconds: -1000,
+});
+
+let time = Temporal.PlainTime.from({
+  microsecond: 1,
+});
+
+let result = time.subtract(duration);
+
+TemporalHelpers.assertPlainTime(result, 23, 47, 34, 740, 993, 0);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/precision-exact-mathematical-values-2.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/precision-exact-mathematical-values-2.js
new file mode 100644
index 0000000000..b224786342
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/precision-exact-mathematical-values-2.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: >
+  Duration components are precise mathematical integers.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+let duration = Temporal.Duration.from({
+  hours: -Number.MAX_VALUE,
+  minutes: -Number.MAX_VALUE,
+});
+
+let time = new Temporal.PlainTime(0, 0, 0, 0, 0, 0);
+
+let result = time.subtract(duration);
+
+TemporalHelpers.assertPlainTime(result, 10, 8, 0, 0, 0, 0);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/precision-exact-mathematical-values-3.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/precision-exact-mathematical-values-3.js
new file mode 100644
index 0000000000..ca2be8e8ca
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/precision-exact-mathematical-values-3.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: >
+  Duration components are precise mathematical integers.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+let duration = Temporal.Duration.from({
+  hours: -Number.MAX_VALUE,
+  minutes: -Number.MAX_VALUE,
+  seconds: -Number.MAX_VALUE,
+  milliseconds: -Number.MAX_VALUE,
+  microseconds: -Number.MAX_VALUE,
+  nanoseconds: -Number.MAX_VALUE,
+});
+
+let time = new Temporal.PlainTime(0, 0, 0, 0, 0, 0);
+
+let result = time.subtract(duration);
+
+TemporalHelpers.assertPlainTime(result, 3, 53, 35, 351, 226, 368);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/prop-desc.js
new file mode 100644
index 0000000000..edda251cf8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/prop-desc.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: The "subtract" property of Temporal.PlainTime.prototype
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+assert.sameValue(
+  typeof Temporal.PlainTime.prototype.subtract,
+  "function",
+  "`typeof PlainTime.prototype.subtract` is `function`"
+);
+
+verifyProperty(Temporal.PlainTime.prototype, "subtract", {
+  writable: true,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/subclassing-ignored.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/subclassing-ignored.js
new file mode 100644
index 0000000000..3cf8dc52a9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/subtract/subclassing-ignored.js
@@ -0,0 +1,20 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.subtract
+description: Objects of a subclass are never created as return values for subtract()
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+TemporalHelpers.checkSubclassingIgnored(
+  Temporal.PlainTime,
+  [12, 34, 56, 987, 654, 321],
+  "subtract",
+  [{ nanoseconds: 1 }],
+  (result) => TemporalHelpers.assertPlainTime(result, 12, 34, 56, 987, 654, 320),
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/basic.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/basic.js
new file mode 100644
index 0000000000..7e8ca0ee74
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/basic.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tojson
+description: Basic behavior for toJSON
+features: [Temporal]
+---*/
+
+const tests = [
+  [new Temporal.PlainTime(5, 3, 1), "05:03:01"],
+  [new Temporal.PlainTime(15, 23), "15:23:00"],
+  [new Temporal.PlainTime(15, 23, 30), "15:23:30"],
+  [new Temporal.PlainTime(15, 23, 30, 123, 400), "15:23:30.1234"],
+];
+
+const options = new Proxy({}, {
+  get() { throw new Test262Error("should not get properties off argument") }
+});
+for (const [time, expected] of tests) {
+  assert.sameValue(time.toJSON(), expected, "toJSON without argument");
+  assert.sameValue(time.toJSON(options), expected, "toJSON with argument");
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/branding.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/branding.js
new file mode 100644
index 0000000000..93967967c5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/branding.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tojson
+description: Throw a TypeError if the receiver is invalid
+features: [Symbol, Temporal]
+---*/
+
+const toJSON = Temporal.PlainTime.prototype.toJSON;
+
+assert.sameValue(typeof toJSON, "function");
+
+assert.throws(TypeError, () => toJSON.call(undefined), "undefined");
+assert.throws(TypeError, () => toJSON.call(null), "null");
+assert.throws(TypeError, () => toJSON.call(true), "true");
+assert.throws(TypeError, () => toJSON.call(""), "empty string");
+assert.throws(TypeError, () => toJSON.call(Symbol()), "symbol");
+assert.throws(TypeError, () => toJSON.call(1), "1");
+assert.throws(TypeError, () => toJSON.call({}), "plain object");
+assert.throws(TypeError, () => toJSON.call(Temporal.PlainTime), "Temporal.PlainTime");
+assert.throws(TypeError, () => toJSON.call(Temporal.PlainTime.prototype), "Temporal.PlainTime.prototype");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/builtin.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/builtin.js
new file mode 100644
index 0000000000..64b83f9358
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/builtin.js
@@ -0,0 +1,36 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tojson
+description: >
+    Tests that Temporal.PlainTime.prototype.toJSON
+    meets the requirements for built-in objects defined by the
+    introduction of chapter 17 of the ECMAScript Language Specification.
+info: |
+    Built-in functions that are not constructors do not have a "prototype" property unless
+    otherwise specified in the description of a particular function.
+
+    Unless specified otherwise, a built-in object that is callable as a function is a built-in
+    function object with the characteristics described in 10.3. Unless specified otherwise, the
+    [[Extensible]] internal slot of a built-in object initially has the value true.
+
+    Unless otherwise specified every built-in function and every built-in constructor has the
+    Function prototype object [...] as the value of its [[Prototype]] internal slot.
+features: [Temporal]
+---*/
+
+assert.sameValue(Object.isExtensible(Temporal.PlainTime.prototype.toJSON),
+  true, "Built-in objects must be extensible.");
+
+assert.sameValue(Object.prototype.toString.call(Temporal.PlainTime.prototype.toJSON),
+  "[object Function]", "Object.prototype.toString");
+
+assert.sameValue(Object.getPrototypeOf(Temporal.PlainTime.prototype.toJSON),
+  Function.prototype, "prototype");
+
+assert.sameValue(Temporal.PlainTime.prototype.toJSON.hasOwnProperty("prototype"),
+  false, "prototype property");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/length.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/length.js
new file mode 100644
index 0000000000..a1fa8b2e3c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/length.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tojson
+description: Temporal.PlainTime.prototype.toJSON.length is 0
+info: |
+    Every built-in function object, including constructors, has a "length" property whose value is
+    an integer. Unless otherwise specified, this value is equal to the largest number of named
+    arguments shown in the subclause headings for the function description. Optional parameters
+    (which are indicated with brackets: [ ]) or rest parameters (which are shown using the form
+    «...name») are not included in the default argument count.
+
+    Unless otherwise specified, the "length" property of a built-in function object has the
+    attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.toJSON, "length", {
+  value: 0,
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/name.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/name.js
new file mode 100644
index 0000000000..d900bcd5bc
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/name.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tojson
+description: Temporal.PlainTime.prototype.toJSON.name is "toJSON".
+info: |
+    Every built-in function object, including constructors, that is not identified as an anonymous
+    function has a "name" property whose value is a String. Unless otherwise specified, this value
+    is the name that is given to the function in this specification.
+
+    Unless otherwise specified, the "name" property of a built-in function object, if it exists,
+    has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.toJSON, "name", {
+  value: "toJSON",
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/not-a-constructor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/not-a-constructor.js
new file mode 100644
index 0000000000..3aaff59047
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/not-a-constructor.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tojson
+description: >
+  Temporal.PlainTime.prototype.toJSON does not implement [[Construct]], is not new-able
+info: |
+    Built-in function objects that are not identified as constructors do not implement the
+    [[Construct]] internal method unless otherwise specified in the description of a particular
+    function.
+includes: [isConstructor.js]
+features: [Reflect.construct, Temporal]
+---*/
+
+assert.throws(TypeError, () => {
+  new Temporal.PlainTime.prototype.toJSON();
+}, "Calling as constructor");
+
+assert.sameValue(isConstructor(Temporal.PlainTime.prototype.toJSON), false,
+  "isConstructor(Temporal.PlainTime.prototype.toJSON)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/prop-desc.js
new file mode 100644
index 0000000000..d9a41bfcf3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/prop-desc.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tojson
+description: The "toJSON" property of Temporal.PlainTime.prototype
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+assert.sameValue(
+  typeof Temporal.PlainTime.prototype.toJSON,
+  "function",
+  "`typeof PlainTime.prototype.toJSON` is `function`"
+);
+
+verifyProperty(Temporal.PlainTime.prototype, "toJSON", {
+  writable: true,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toJSON/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/branding.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/branding.js
new file mode 100644
index 0000000000..8b915d6f23
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/branding.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tolocalestring
+description: Throw a TypeError if the receiver is invalid
+features: [Symbol, Temporal]
+---*/
+
+const toLocaleString = Temporal.PlainTime.prototype.toLocaleString;
+
+assert.sameValue(typeof toLocaleString, "function");
+
+assert.throws(TypeError, () => toLocaleString.call(undefined), "undefined");
+assert.throws(TypeError, () => toLocaleString.call(null), "null");
+assert.throws(TypeError, () => toLocaleString.call(true), "true");
+assert.throws(TypeError, () => toLocaleString.call(""), "empty string");
+assert.throws(TypeError, () => toLocaleString.call(Symbol()), "symbol");
+assert.throws(TypeError, () => toLocaleString.call(1), "1");
+assert.throws(TypeError, () => toLocaleString.call({}), "plain object");
+assert.throws(TypeError, () => toLocaleString.call(Temporal.PlainTime), "Temporal.PlainTime");
+assert.throws(TypeError, () => toLocaleString.call(Temporal.PlainTime.prototype), "Temporal.PlainTime.prototype");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/builtin.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/builtin.js
new file mode 100644
index 0000000000..e6af716c69
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/builtin.js
@@ -0,0 +1,36 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tolocalestring
+description: >
+    Tests that Temporal.PlainTime.prototype.toLocaleString
+    meets the requirements for built-in objects defined by the
+    introduction of chapter 17 of the ECMAScript Language Specification.
+info: |
+    Built-in functions that are not constructors do not have a "prototype" property unless
+    otherwise specified in the description of a particular function.
+
+    Unless specified otherwise, a built-in object that is callable as a function is a built-in
+    function object with the characteristics described in 10.3. Unless specified otherwise, the
+    [[Extensible]] internal slot of a built-in object initially has the value true.
+
+    Unless otherwise specified every built-in function and every built-in constructor has the
+    Function prototype object [...] as the value of its [[Prototype]] internal slot.
+features: [Temporal]
+---*/
+
+assert.sameValue(Object.isExtensible(Temporal.PlainTime.prototype.toLocaleString),
+  true, "Built-in objects must be extensible.");
+
+assert.sameValue(Object.prototype.toString.call(Temporal.PlainTime.prototype.toLocaleString),
+  "[object Function]", "Object.prototype.toString");
+
+assert.sameValue(Object.getPrototypeOf(Temporal.PlainTime.prototype.toLocaleString),
+  Function.prototype, "prototype");
+
+assert.sameValue(Temporal.PlainTime.prototype.toLocaleString.hasOwnProperty("prototype"),
+  false, "prototype property");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/length.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/length.js
new file mode 100644
index 0000000000..626a8f7207
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/length.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tolocalestring
+description: Temporal.PlainTime.prototype.toLocaleString.length is 0
+info: |
+    Every built-in function object, including constructors, has a "length" property whose value is
+    an integer. Unless otherwise specified, this value is equal to the largest number of named
+    arguments shown in the subclause headings for the function description. Optional parameters
+    (which are indicated with brackets: [ ]) or rest parameters (which are shown using the form
+    «...name») are not included in the default argument count.
+
+    Unless otherwise specified, the "length" property of a built-in function object has the
+    attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.toLocaleString, "length", {
+  value: 0,
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/name.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/name.js
new file mode 100644
index 0000000000..cd6f7bd904
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/name.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tolocalestring
+description: Temporal.PlainTime.prototype.toLocaleString.name is "toLocaleString".
+info: |
+    Every built-in function object, including constructors, that is not identified as an anonymous
+    function has a "name" property whose value is a String. Unless otherwise specified, this value
+    is the name that is given to the function in this specification.
+
+    Unless otherwise specified, the "name" property of a built-in function object, if it exists,
+    has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.toLocaleString, "name", {
+  value: "toLocaleString",
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/not-a-constructor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/not-a-constructor.js
new file mode 100644
index 0000000000..4f5fd664fb
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/not-a-constructor.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tolocalestring
+description: >
+  Temporal.PlainTime.prototype.toLocaleString does not implement [[Construct]], is not new-able
+info: |
+    Built-in function objects that are not identified as constructors do not implement the
+    [[Construct]] internal method unless otherwise specified in the description of a particular
+    function.
+includes: [isConstructor.js]
+features: [Reflect.construct, Temporal]
+---*/
+
+assert.throws(TypeError, () => {
+  new Temporal.PlainTime.prototype.toLocaleString();
+}, "Calling as constructor");
+
+assert.sameValue(isConstructor(Temporal.PlainTime.prototype.toLocaleString), false,
+  "isConstructor(Temporal.PlainTime.prototype.toLocaleString)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/prop-desc.js
new file mode 100644
index 0000000000..febb8c707c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/prop-desc.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tolocalestring
+description: The "toLocaleString" property of Temporal.PlainTime.prototype
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+assert.sameValue(
+  typeof Temporal.PlainTime.prototype.toLocaleString,
+  "function",
+  "`typeof PlainTime.prototype.toLocaleString` is `function`"
+);
+
+verifyProperty(Temporal.PlainTime.prototype, "toLocaleString", {
+  writable: true,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/return-string.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/return-string.js
new file mode 100644
index 0000000000..1ea5af8ba9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/return-string.js
@@ -0,0 +1,16 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Kate Miháliková. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tolocalestring
+description: >
+    toLocaleString return a string.
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+assert.sameValue(typeof time.toLocaleString("en", { timeStyle: "short" }), "string");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toLocaleString/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-calendar-datefromfields-called-with-null-prototype-fields.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-calendar-datefromfields-called-with-null-prototype-fields.js
new file mode 100644
index 0000000000..9c9399b1ad
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-calendar-datefromfields-called-with-null-prototype-fields.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: >
+    Calendar.dateFromFields method is called with a null-prototype fields object
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const calendar = TemporalHelpers.calendarCheckFieldsPrototypePollution();
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+const arg = { year: 2000, month: 5, day: 2, calendar };
+instance.toPlainDateTime(arg);
+assert.sameValue(calendar.dateFromFieldsCallCount, 1, "dateFromFields should be called on the property bag's calendar");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-leap-second.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-leap-second.js
new file mode 100644
index 0000000000..23d044c61e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-leap-second.js
@@ -0,0 +1,30 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: Leap second is a valid ISO string for PlainDate
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+let arg = "2016-12-31T23:59:60";
+const result1 = instance.toPlainDateTime(arg);
+TemporalHelpers.assertPlainDateTime(
+  result1,
+  2016, 12, "M12", 31, 12, 34, 56, 987, 654, 321,
+  "leap second is a valid ISO string for PlainDate"
+);
+
+arg = { year: 2016, month: 12, day: 31, hour: 23, minute: 59, second: 60 };
+const result2 = instance.toPlainDateTime(arg);
+TemporalHelpers.assertPlainDateTime(
+  result2,
+  2016, 12, "M12", 31, 12, 34, 56, 987, 654, 321,
+  "second: 60 is ignored in property bag for PlainDate"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-number.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-number.js
new file mode 100644
index 0000000000..508d95fbf0
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-number.js
@@ -0,0 +1,33 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: A number is converted to a string, then to Temporal.PlainDate
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const arg = 19761118;
+
+const result = instance.toPlainDateTime(arg);
+TemporalHelpers.assertPlainDateTime(result, 1976, 11, "M11", 18, 12, 34, 56, 987, 654, 321, "19761118 is a valid ISO string for PlainDate");
+
+const numbers = [
+  1,
+  -19761118,
+  1234567890,
+];
+
+for (const arg of numbers) {
+  assert.throws(
+    RangeError,
+    () => instance.toPlainDateTime(arg),
+    `Number ${arg} does not convert to a valid ISO string for PlainDate`
+  );
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-plaindatetime.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-plaindatetime.js
new file mode 100644
index 0000000000..55cd85850a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-plaindatetime.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.toplaindatetime
+description: Fast path for converting Temporal.PlainDateTime to Temporal.PlainDate by reading internal slots
+info: |
+    sec-temporal.plaintime.prototype.toplaindatetime step 3:
+      3. Set _temporalDate_ to ? ToTemporalDate(_temporalDate_).
+    sec-temporal-totemporaldate step 2.b:
+      b. If _item_ has an [[InitializedTemporalDateTime]] internal slot, then
+        i. Return ! CreateTemporalDate(_item_.[[ISOYear]], _item_.[[ISOMonth]], _item_.[[ISODay]], _item_.[[Calendar]]).
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+TemporalHelpers.checkPlainDateTimeConversionFastPath((datetime) => {
+  const time = new Temporal.PlainTime(6, 54, 32, 123, 456, 789);
+  const result = time.toPlainDateTime(datetime);
+  TemporalHelpers.assertPlainDateTime(result, 2000, 5, "M05", 2, 6, 54, 32, 123, 456, 789);
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-propertybag-calendar-case-insensitive.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-propertybag-calendar-case-insensitive.js
new file mode 100644
index 0000000000..b59b2e65c6
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-propertybag-calendar-case-insensitive.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: The calendar name is case-insensitive
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const calendar = "IsO8601";
+
+let arg = { year: 1976, monthCode: "M11", day: 18, calendar };
+const result1 = instance.toPlainDateTime(arg);
+TemporalHelpers.assertPlainDateTime(result1, 1976, 11, "M11", 18, 12, 34, 56, 987, 654, 321, "Calendar is case-insensitive");
+
+arg = { year: 1976, monthCode: "M11", day: 18, calendar: { calendar } };
+const result2 = instance.toPlainDateTime(arg);
+TemporalHelpers.assertPlainDateTime(result2, 1976, 11, "M11", 18, 12, 34, 56, 987, 654, 321, "Calendar is case-insensitive (nested property)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-propertybag-calendar-instance-does-not-get-calendar-property.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-propertybag-calendar-instance-does-not-get-calendar-property.js
new file mode 100644
index 0000000000..a3464eede8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-propertybag-calendar-instance-does-not-get-calendar-property.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: >
+  A Temporal.Calendar instance passed to toPlainDateTime() in a property bag does
+  not have its 'calendar' property observably checked
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const calendar = new Temporal.Calendar("iso8601");
+Object.defineProperty(calendar, "calendar", {
+  get() {
+    throw new Test262Error("calendar.calendar should not be accessed");
+  },
+});
+
+let arg = { year: 1976, monthCode: "M11", day: 18, calendar };
+instance.toPlainDateTime(arg);
+
+arg = { year: 1976, monthCode: "M11", day: 18, calendar: { calendar } };
+instance.toPlainDateTime(arg);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-propertybag-calendar-leap-second.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-propertybag-calendar-leap-second.js
new file mode 100644
index 0000000000..491351f66a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-propertybag-calendar-leap-second.js
@@ -0,0 +1,32 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: Leap second is a valid ISO string for a calendar in a property bag
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const calendar = "2016-12-31T23:59:60";
+
+let arg = { year: 1976, monthCode: "M11", day: 18, calendar };
+const result1 = instance.toPlainDateTime(arg);
+TemporalHelpers.assertPlainDateTime(
+  result1,
+  1976, 11, "M11", 18, 12, 34, 56, 987, 654, 321,
+  "leap second is a valid ISO string for calendar"
+);
+
+arg = { year: 1976, monthCode: "M11", day: 18, calendar: { calendar } };
+const result2 = instance.toPlainDateTime(arg);
+TemporalHelpers.assertPlainDateTime(
+  result2,
+  1976, 11, "M11", 18, 12, 34, 56, 987, 654, 321,
+  "leap second is a valid ISO string for calendar (nested property)"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-propertybag-calendar-number.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-propertybag-calendar-number.js
new file mode 100644
index 0000000000..f45fea77cc
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-propertybag-calendar-number.js
@@ -0,0 +1,45 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: A number as calendar in a property bag is converted to a string, then to a calendar
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const calendar = 19970327;
+
+let arg = { year: 1976, monthCode: "M11", day: 18, calendar };
+const result1 = instance.toPlainDateTime(arg);
+TemporalHelpers.assertPlainDateTime(result1, 1976, 11, "M11", 18, 12, 34, 56, 987, 654, 321, "19970327 is a valid ISO string for calendar");
+
+arg = { year: 1976, monthCode: "M11", day: 18, calendar: { calendar } };
+const result2 = instance.toPlainDateTime(arg);
+TemporalHelpers.assertPlainDateTime(result2, 1976, 11, "M11", 18, 12, 34, 56, 987, 654, 321, "19970327 is a valid ISO string for calendar (nested property)");
+
+const numbers = [
+  1,
+  -19970327,
+  1234567890,
+];
+
+for (const calendar of numbers) {
+  let arg = { year: 1976, monthCode: "M11", day: 18, calendar };
+  assert.throws(
+    RangeError,
+    () => instance.toPlainDateTime(arg),
+    `Number ${calendar} does not convert to a valid ISO string for calendar`
+  );
+  arg = { year: 1976, monthCode: "M11", day: 18, calendar: { calendar } };
+  assert.throws(
+    RangeError,
+    () => instance.toPlainDateTime(arg),
+    `Number ${calendar} does not convert to a valid ISO string for calendar (nested property)`
+  );
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-propertybag-calendar-string.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-propertybag-calendar-string.js
new file mode 100644
index 0000000000..fd4f3ea2b3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-propertybag-calendar-string.js
@@ -0,0 +1,20 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: A calendar ID is valid input for Calendar
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const calendar = "iso8601";
+
+const arg = { year: 1976, monthCode: "M11", day: 18, calendar };
+const result = instance.toPlainDateTime(arg);
+TemporalHelpers.assertPlainDateTime(result, 1976, 11, "M11", 18, 12, 34, 56, 987, 654, 321, `Calendar created from string "${calendar}"`);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-propertybag-calendar-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-propertybag-calendar-wrong-type.js
new file mode 100644
index 0000000000..b0e83ff951
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-propertybag-calendar-wrong-type.js
@@ -0,0 +1,50 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: >
+  Appropriate error thrown when a calendar property from a property bag cannot
+  be converted to a calendar object or string
+features: [BigInt, Symbol, Temporal]
+---*/
+
+const timeZone = new Temporal.TimeZone("UTC");
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const rangeErrorTests = [
+  [null, "null"],
+  [true, "boolean"],
+  ["", "empty string"],
+  [1, "number that doesn't convert to a valid ISO string"],
+  [1n, "bigint"],
+];
+
+for (const [calendar, description] of rangeErrorTests) {
+  let arg = { year: 2019, monthCode: "M11", day: 1, calendar };
+  assert.throws(RangeError, () => instance.toPlainDateTime(arg), `${description} does not convert to a valid ISO string`);
+
+  arg = { year: 2019, monthCode: "M11", day: 1, calendar: { calendar } };
+  assert.throws(RangeError, () => instance.toPlainDateTime(arg), `${description} does not convert to a valid ISO string (nested property)`);
+}
+
+const typeErrorTests = [
+  [Symbol(), "symbol"],
+  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
+];
+
+for (const [calendar, description] of typeErrorTests) {
+  let arg = { year: 2019, monthCode: "M11", day: 1, calendar };
+  assert.throws(TypeError, () => instance.toPlainDateTime(arg), `${description} is not a valid property bag and does not convert to a string`);
+
+  arg = { year: 2019, monthCode: "M11", day: 1, calendar: { calendar } };
+  assert.throws(TypeError, () => instance.toPlainDateTime(arg), `${description} is not a valid property bag and does not convert to a string (nested property)`);
+}
+
+const arg = { year: 2019, monthCode: "M11", day: 1, calendar: { calendar: undefined } };
+assert.throws(RangeError, () => instance.toPlainDateTime(arg), `nested undefined calendar property is always a RangeError`);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-propertybag-calendar-year-zero.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-propertybag-calendar-year-zero.js
new file mode 100644
index 0000000000..424b44dba7
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-propertybag-calendar-year-zero.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: Negative zero, as an extended year, is rejected
+features: [Temporal, arrow-function]
+---*/
+
+const invalidStrings = [
+  "-000000-10-31",
+  "-000000-10-31T17:45",
+  "-000000-10-31T17:45Z",
+  "-000000-10-31T17:45+01:00",
+  "-000000-10-31T17:45+00:00[UTC]",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => instance.toPlainDateTime(arg),
+    "reject minus zero as extended year"
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-calendar-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-calendar-annotation.js
new file mode 100644
index 0000000000..a4febf00b0
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-calendar-annotation.js
@@ -0,0 +1,35 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: Various forms of calendar annotation; critical flag has no effect
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const tests = [
+  ["2000-05-02[u-ca=iso8601]", "without time or time zone"],
+  ["2000-05-02[UTC][u-ca=iso8601]", "with time zone and no time"],
+  ["2000-05-02T15:23[u-ca=iso8601]", "without time zone"],
+  ["2000-05-02T15:23[UTC][u-ca=iso8601]", "with time zone"],
+  ["2000-05-02T15:23[!u-ca=iso8601]", "with ! and no time zone"],
+  ["2000-05-02T15:23[UTC][!u-ca=iso8601]", "with ! and time zone"],
+  ["2000-05-02T15:23[u-ca=iso8601][u-ca=discord]", "second annotation ignored"],
+  ["2000-05-02T15:23[u-ca=iso8601][!u-ca=discord]", "second annotation ignored even with !"],
+];
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+tests.forEach(([arg, description]) => {
+  const result = instance.toPlainDateTime(arg);
+
+  TemporalHelpers.assertPlainDateTime(
+    result,
+    2000, 5, "M05", 2, 12, 34, 56, 987, 654, 321,
+    `calendar annotation (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-critical-unknown-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-critical-unknown-annotation.js
new file mode 100644
index 0000000000..46384e588d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-critical-unknown-annotation.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: Unknown annotations with critical flag are rejected
+features: [Temporal]
+---*/
+
+const invalidStrings = [
+  "1970-01-01[!foo=bar]",
+  "1970-01-01T00:00[!foo=bar]",
+  "1970-01-01T00:00[UTC][!foo=bar]",
+  "1970-01-01T00:00[u-ca=iso8601][!foo=bar]",
+  "1970-01-01T00:00[UTC][!foo=bar][u-ca=iso8601]",
+  "1970-01-01T00:00[foo=bar][!_foo-bar0=Dont-Ignore-This-99999999999]",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => instance.toPlainDateTime(arg),
+    `reject unknown annotation with critical flag: ${arg}`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-date-with-utc-offset.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-date-with-utc-offset.js
new file mode 100644
index 0000000000..21bf8f1c80
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-date-with-utc-offset.js
@@ -0,0 +1,49 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: UTC offset not valid with format that does not include a time
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const validStrings = [
+  "2000-05-02T00+00:00",
+  "2000-05-02T00+00:00[UTC]",
+  "2000-05-02T00+00:00[!UTC]",
+  "2000-05-02T00-02:30[America/St_Johns]",
+];
+
+for (const arg of validStrings) {
+  const result = instance.toPlainDateTime(arg);
+
+  TemporalHelpers.assertPlainDateTime(
+    result,
+    2000, 5, "M05", 2, 12, 34, 56, 987, 654, 321,
+    `"${arg}" is a valid UTC offset with time for PlainDate`
+  );
+}
+
+const invalidStrings = [
+  "2022-09-15Z",
+  "2022-09-15Z[UTC]",
+  "2022-09-15Z[Europe/Vienna]",
+  "2022-09-15+00:00",
+  "2022-09-15+00:00[UTC]",
+  "2022-09-15-02:30",
+  "2022-09-15-02:30[America/St_Johns]",
+];
+
+for (const arg of invalidStrings) {
+  assert.throws(
+    RangeError,
+    () => instance.toPlainDateTime(arg),
+    `"${arg}" UTC offset without time is not valid for PlainDate`
+  );
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-invalid.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-invalid.js
new file mode 100644
index 0000000000..cf1c226034
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-invalid.js
@@ -0,0 +1,64 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: >
+  RangeError thrown if an invalid ISO string (or syntactically valid ISO string
+  that is not supported) is used as a PlainDate
+features: [Temporal, arrow-function]
+---*/
+
+const invalidStrings = [
+  // invalid ISO strings:
+  "",
+  "invalid iso8601",
+  "2020-01-00",
+  "2020-01-32",
+  "2020-02-30",
+  "2021-02-29",
+  "2020-00-01",
+  "2020-13-01",
+  "2020-01-01T",
+  "2020-01-01T25:00:00",
+  "2020-01-01T01:60:00",
+  "2020-01-01T01:60:61",
+  "2020-01-01junk",
+  "2020-01-01T00:00:00junk",
+  "2020-01-01T00:00:00+00:00junk",
+  "2020-01-01T00:00:00+00:00[UTC]junk",
+  "2020-01-01T00:00:00+00:00[UTC][u-ca=iso8601]junk",
+  "02020-01-01",
+  "2020-001-01",
+  "2020-01-001",
+  "2020-01-01T001",
+  "2020-01-01T01:001",
+  "2020-01-01T01:01:001",
+  // valid, but forms not supported in Temporal:
+  "2020-W01-1",
+  "2020-001",
+  "+0002020-01-01",
+  // valid, but this calendar must not exist:
+  "2020-01-01[u-ca=notexist]",
+  // may be valid in other contexts, but insufficient information for PlainDate:
+  "2020-01",
+  "+002020-01",
+  "01-01",
+  "2020-W01",
+  "P1Y",
+  "-P12Y",
+  // valid, but outside the supported range:
+  "-999999-01-01",
+  "+999999-01-01",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+for (const arg of invalidStrings) {
+  assert.throws(
+    RangeError,
+    () => instance.toPlainDateTime(arg),
+    `"${arg}" should not be a valid ISO string for a PlainDate`
+  );
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-multiple-time-zone.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-multiple-time-zone.js
new file mode 100644
index 0000000000..1f0c2e3c85
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-multiple-time-zone.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: More than one time zone annotation is not syntactical
+features: [Temporal]
+---*/
+
+const invalidStrings = [
+  "1970-01-01[UTC][UTC]",
+  "1970-01-01T00:00[UTC][UTC]",
+  "1970-01-01T00:00[!UTC][UTC]",
+  "1970-01-01T00:00[UTC][!UTC]",
+  "1970-01-01T00:00[UTC][u-ca=iso8601][UTC]",
+  "1970-01-01T00:00[UTC][foo=bar][UTC]",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => instance.toPlainDateTime(arg),
+    `reject more than one time zone annotation: ${arg}`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-time-separators.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-time-separators.js
new file mode 100644
index 0000000000..50c650da7a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-time-separators.js
@@ -0,0 +1,30 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: Time separator in string argument can vary
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const tests = [
+  ["2000-05-02T15:23", "uppercase T"],
+  ["2000-05-02t15:23", "lowercase T"],
+  ["2000-05-02 15:23", "space between date and time"],
+];
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+tests.forEach(([arg, description]) => {
+  const result = instance.toPlainDateTime(arg);
+
+  TemporalHelpers.assertPlainDateTime(
+    result,
+    2000, 5, "M05", 2, 12, 34, 56, 987, 654, 321,
+    `variant time separators (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-time-zone-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-time-zone-annotation.js
new file mode 100644
index 0000000000..93cc41068e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-time-zone-annotation.js
@@ -0,0 +1,39 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: Various forms of time zone annotation; critical flag has no effect
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const tests = [
+  ["2000-05-02[Asia/Kolkata]", "named, with no time"],
+  ["2000-05-02[!Europe/Vienna]", "named, with ! and no time"],
+  ["2000-05-02[+00:00]", "numeric, with no time"],
+  ["2000-05-02[!-02:30]", "numeric, with ! and no time"],
+  ["2000-05-02T15:23[America/Sao_Paulo]", "named, with no offset"],
+  ["2000-05-02T15:23[!Asia/Tokyo]", "named, with ! and no offset"],
+  ["2000-05-02T15:23[-02:30]", "numeric, with no offset"],
+  ["2000-05-02T15:23[!+00:00]", "numeric, with ! and no offset"],
+  ["2000-05-02T15:23+00:00[America/New_York]", "named, with offset"],
+  ["2000-05-02T15:23+00:00[!UTC]", "named, with offset and !"],
+  ["2000-05-02T15:23+00:00[+01:00]", "numeric, with offset"],
+  ["2000-05-02T15:23+00:00[!-08:00]", "numeric, with offset and !"],
+];
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+tests.forEach(([arg, description]) => {
+  const result = instance.toPlainDateTime(arg);
+
+  TemporalHelpers.assertPlainDateTime(
+    result,
+    2000, 5, "M05", 2, 12, 34, 56, 987, 654, 321,
+    `time zone annotation (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-unknown-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-unknown-annotation.js
new file mode 100644
index 0000000000..95cd49359e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-unknown-annotation.js
@@ -0,0 +1,33 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: Various forms of unknown annotation
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const tests = [
+  ["2000-05-02[foo=bar]", "without time"],
+  ["2000-05-02T15:23[foo=bar]", "alone"],
+  ["2000-05-02T15:23[UTC][foo=bar]", "with time zone"],
+  ["2000-05-02T15:23[u-ca=iso8601][foo=bar]", "with calendar"],
+  ["2000-05-02T15:23[UTC][foo=bar][u-ca=iso8601]", "with time zone and calendar"],
+  ["2000-05-02T15:23[foo=bar][_foo-bar0=Ignore-This-999999999999]", "with another unknown annotation"],
+];
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+tests.forEach(([arg, description]) => {
+  const result = instance.toPlainDateTime(arg);
+
+  TemporalHelpers.assertPlainDateTime(
+    result,
+    2000, 5, "M05", 2, 12, 34, 56, 987, 654, 321,
+    `unknown annotation (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-with-utc-designator.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-with-utc-designator.js
new file mode 100644
index 0000000000..123e4e10af
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-with-utc-designator.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: RangeError thrown if a string with UTC designator is used as a PlainDate
+features: [Temporal, arrow-function]
+---*/
+
+const invalidStrings = [
+  "2019-10-01T09:00:00Z",
+  "2019-10-01T09:00:00Z[UTC]",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => instance.toPlainDateTime(arg),
+    "String with UTC designator should not be valid as a PlainDate"
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-wrong-type.js
new file mode 100644
index 0000000000..22cca4e14c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-wrong-type.js
@@ -0,0 +1,39 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: >
+  Appropriate error thrown when argument cannot be converted to a valid string
+  or property bag for PlainDate
+features: [BigInt, Symbol, Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const rangeErrorTests = [
+  [undefined, "undefined"],
+  [null, "null"],
+  [true, "boolean"],
+  ["", "empty string"],
+  [1, "number that doesn't convert to a valid ISO string"],
+  [1n, "bigint"],
+];
+
+for (const [arg, description] of rangeErrorTests) {
+  assert.throws(RangeError, () => instance.toPlainDateTime(arg), `${description} does not convert to a valid ISO string`);
+}
+
+const typeErrorTests = [
+  [Symbol(), "symbol"],
+  [{}, "plain object"],
+  [Temporal.PlainDate, "Temporal.PlainDate, object"],
+  [Temporal.PlainDate.prototype, "Temporal.PlainDate.prototype, object"],
+];
+
+for (const [arg, description] of typeErrorTests) {
+  assert.throws(TypeError, () => instance.toPlainDateTime(arg), `${description} is not a valid property bag and does not convert to a string`);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-zoneddatetime-convert.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-zoneddatetime-convert.js
new file mode 100644
index 0000000000..1430ea9c42
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-zoneddatetime-convert.js
@@ -0,0 +1,22 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: An exception from TimeZone#getOffsetNanosecondsFor() is propagated.
+features: [Temporal]
+---*/
+
+class TZ extends Temporal.TimeZone {
+  constructor() { super("UTC") }
+  getOffsetNanosecondsFor() { throw new Test262Error() }
+}
+
+const tz = new TZ();
+const arg = new Temporal.ZonedDateTime(0n, tz);
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+assert.throws(Test262Error, () => instance.toPlainDateTime(arg));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-zoneddatetime-slots.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-zoneddatetime-slots.js
new file mode 100644
index 0000000000..bedf8b74bb
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-zoneddatetime-slots.js
@@ -0,0 +1,40 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: Getters are not called when converting a ZonedDateTime to a PlainDate.
+includes: [compareArray.js]
+features: [Temporal]
+---*/
+
+const actual = [];
+const prototypeDescrs = Object.getOwnPropertyDescriptors(Temporal.ZonedDateTime.prototype);
+const getters = ["year", "month", "monthCode", "day", "hour", "minute", "second", "millisecond", "microsecond", "nanosecond", "calendar"];
+
+for (const property of getters) {
+  Object.defineProperty(Temporal.ZonedDateTime.prototype, property, {
+    get() {
+      actual.push(`get ${property}`);
+      const value = prototypeDescrs[property].get.call(this);
+      return {
+        toString() {
+          actual.push(`toString ${property}`);
+          return value.toString();
+        },
+        valueOf() {
+          actual.push(`valueOf ${property}`);
+          return value;
+        },
+      };
+    },
+  });
+}
+
+const arg = new Temporal.ZonedDateTime(0n, "UTC");
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+instance.toPlainDateTime(arg);
+assert.compareArray(actual, []);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-non-integer.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-non-integer.js
new file mode 100644
index 0000000000..868f43cc76
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-non-integer.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: RangeError thrown if time zone reports an offset that is not an integer number of nanoseconds
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[3600_000_000_000.5, NaN, -Infinity, Infinity].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  assert.throws(RangeError, () => time.toPlainDateTime(datetime));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js
new file mode 100644
index 0000000000..965ea63146
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js
@@ -0,0 +1,23 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: TypeError thrown if timeZone.getOffsetNanosecondsFor is not callable
+features: [BigInt, Symbol, Temporal, arrow-function]
+---*/
+
+[undefined, null, true, Math.PI, 'string', Symbol('sym'), 42n, {}].forEach((notCallable) => {
+  const timeZone = new Temporal.TimeZone("UTC");
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  timeZone.getOffsetNanosecondsFor = notCallable;
+  assert.throws(
+    TypeError,
+    () => time.toPlainDateTime(datetime),
+    `Uncallable ${notCallable === null ? 'null' : typeof notCallable} getOffsetNanosecondsFor should throw TypeError`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-out-of-range.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-out-of-range.js
new file mode 100644
index 0000000000..7f07c56ce0
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-out-of-range.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: RangeError thrown if time zone reports an offset that is out of range
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[-86400_000_000_000, 86400_000_000_000].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  assert.throws(RangeError, () => time.toPlainDateTime(datetime));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-wrong-type.js
new file mode 100644
index 0000000000..3fb6bebbba
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-wrong-type.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: TypeError thrown if time zone reports an offset that is not a Number
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[
+  undefined,
+  null,
+  true,
+  "+01:00",
+  Symbol(),
+  3600_000_000_000n,
+  {},
+  { valueOf() { return 3600_000_000_000; } },
+].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  assert.throws(TypeError, () => time.toPlainDateTime(datetime));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/basic.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/basic.js
new file mode 100644
index 0000000000..309c26fee5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/basic.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.toplaindatetime
+description: Basic tests for toPlainDateTime().
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const plainTime = Temporal.PlainTime.from("11:30:23.123456789");
+
+const plainDate = plainTime.toPlainDateTime(Temporal.PlainDate.from("1976-11-18"));
+TemporalHelpers.assertPlainDateTime(plainDate, 1976, 11, "M11", 18, 11, 30, 23, 123, 456, 789, "PlainDate");
+
+const optionBag = plainTime.toPlainDateTime({ year: 1976, month: 11, day: 18 });
+TemporalHelpers.assertPlainDateTime(optionBag, 1976, 11, "M11", 18, 11, 30, 23, 123, 456, 789, "option bag");
+
+const string = plainTime.toPlainDateTime("1976-11-18");
+TemporalHelpers.assertPlainDateTime(string, 1976, 11, "M11", 18, 11, 30, 23, 123, 456, 789, "string");
+
+assert.throws(TypeError, () => plainTime.toPlainDateTime({ year: 1976 }), "missing properties");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/branding.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/branding.js
new file mode 100644
index 0000000000..17b528d2cc
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/branding.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: Throw a TypeError if the receiver is invalid
+features: [Symbol, Temporal]
+---*/
+
+const toPlainDateTime = Temporal.PlainTime.prototype.toPlainDateTime;
+
+assert.sameValue(typeof toPlainDateTime, "function");
+
+const args = [new Temporal.PlainDate(2022, 6, 22)];
+
+assert.throws(TypeError, () => toPlainDateTime.apply(undefined, args), "undefined");
+assert.throws(TypeError, () => toPlainDateTime.apply(null, args), "null");
+assert.throws(TypeError, () => toPlainDateTime.apply(true, args), "true");
+assert.throws(TypeError, () => toPlainDateTime.apply("", args), "empty string");
+assert.throws(TypeError, () => toPlainDateTime.apply(Symbol(), args), "symbol");
+assert.throws(TypeError, () => toPlainDateTime.apply(1, args), "1");
+assert.throws(TypeError, () => toPlainDateTime.apply({}, args), "plain object");
+assert.throws(TypeError, () => toPlainDateTime.apply(Temporal.PlainTime, args), "Temporal.PlainTime");
+assert.throws(TypeError, () => toPlainDateTime.apply(Temporal.PlainTime.prototype, args), "Temporal.PlainTime.prototype");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/builtin.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/builtin.js
new file mode 100644
index 0000000000..f463135fb4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/builtin.js
@@ -0,0 +1,36 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: >
+    Tests that Temporal.PlainTime.prototype.toPlainDateTime
+    meets the requirements for built-in objects defined by the
+    introduction of chapter 17 of the ECMAScript Language Specification.
+info: |
+    Built-in functions that are not constructors do not have a "prototype" property unless
+    otherwise specified in the description of a particular function.
+
+    Unless specified otherwise, a built-in object that is callable as a function is a built-in
+    function object with the characteristics described in 10.3. Unless specified otherwise, the
+    [[Extensible]] internal slot of a built-in object initially has the value true.
+
+    Unless otherwise specified every built-in function and every built-in constructor has the
+    Function prototype object [...] as the value of its [[Prototype]] internal slot.
+features: [Temporal]
+---*/
+
+assert.sameValue(Object.isExtensible(Temporal.PlainTime.prototype.toPlainDateTime),
+  true, "Built-in objects must be extensible.");
+
+assert.sameValue(Object.prototype.toString.call(Temporal.PlainTime.prototype.toPlainDateTime),
+  "[object Function]", "Object.prototype.toString");
+
+assert.sameValue(Object.getPrototypeOf(Temporal.PlainTime.prototype.toPlainDateTime),
+  Function.prototype, "prototype");
+
+assert.sameValue(Temporal.PlainTime.prototype.toPlainDateTime.hasOwnProperty("prototype"),
+  false, "prototype property");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/calendar-datefromfields-called-with-options-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/calendar-datefromfields-called-with-options-undefined.js
new file mode 100644
index 0000000000..e1ac31f5e6
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/calendar-datefromfields-called-with-options-undefined.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: >
+    Calendar.dateFromFields method is called with undefined as the options value
+    when call originates internally
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const calendar = TemporalHelpers.calendarFromFieldsUndefinedOptions();
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321, calendar);
+instance.toPlainDateTime({ year: 2000, month: 5, day: 3, calendar });
+assert.sameValue(calendar.dateFromFieldsCallCount, 1);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/calendar-fields-iterable.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/calendar-fields-iterable.js
new file mode 100644
index 0000000000..8a1896b1ca
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/calendar-fields-iterable.js
@@ -0,0 +1,34 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: Verify the result of calendar.fields() is treated correctly.
+info: |
+    sec-temporal.plaintime.prototype.toplaindatetime step 3:
+      3. Set _temporalDate_ to ? ToTemporalDate(_temporalDate_).
+    sec-temporal-totemporaldate step 2.c:
+      c. Let _fieldNames_ be ? CalendarFields(_calendar_, « *"day"*, *"month"*, *"monthCode"*, *"year"* »).
+    sec-temporal-calendarfields step 4:
+      4. Let _result_ be ? IterableToList(_fieldsArray_).
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const expected = [
+  "day",
+  "month",
+  "monthCode",
+  "year",
+];
+
+const time = new Temporal.PlainTime(13, 3);
+const calendar = TemporalHelpers.calendarFieldsIterable();
+time.toPlainDateTime({ year: 2000, month: 5, day: 3, calendar });
+
+assert.sameValue(calendar.fieldsCallCount, 1, "fields() method called once");
+assert.compareArray(calendar.fieldsCalledWith[0], expected, "fields() method called with correct args");
+assert(calendar.iteratorExhausted[0], "iterated through the whole iterable");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/calendar-temporal-object.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/calendar-temporal-object.js
new file mode 100644
index 0000000000..455d7f2d7b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/calendar-temporal-object.js
@@ -0,0 +1,30 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: Fast path for converting other Temporal objects to Temporal.Calendar by reading internal slots
+info: |
+    sec-temporal.plaintime.prototype.toplaindatetime step 3:
+      3. Set _temporalDate_ to ? ToTemporalDate(_temporalDate_).
+    sec-temporal-totemporaldate step 2.c:
+      c. Let _calendar_ be ? GetTemporalCalendarWithISODefault(_item_).
+    sec-temporal-gettemporalcalendarwithisodefault step 2:
+      2. Return ? ToTemporalCalendarWithISODefault(_calendar_).
+    sec-temporal-totemporalcalendarwithisodefault step 2:
+      3. Return ? ToTemporalCalendar(_temporalCalendarLike_).
+    sec-temporal-totemporalcalendar step 1.a:
+      a. If _temporalCalendarLike_ has an [[InitializedTemporalDate]], [[InitializedTemporalDateTime]], [[InitializedTemporalMonthDay]], [[InitializedTemporalYearMonth]], or [[InitializedTemporalZonedDateTime]] internal slot, then
+        i. Return _temporalCalendarLike_.[[Calendar]].
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+TemporalHelpers.checkToTemporalCalendarFastPath((temporalObject, calendar) => {
+  const time = new Temporal.PlainTime(13, 3);
+  const result = time.toPlainDateTime({ year: 2000, month: 5, day: 3, calendar: temporalObject });
+  assert.sameValue(result.calendar, calendar, "Temporal object coerced to calendar");
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/infinity-throws-rangeerror.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/infinity-throws-rangeerror.js
new file mode 100644
index 0000000000..5b0c37fe2b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/infinity-throws-rangeerror.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Throws if any value in the property bag is Infinity or -Infinity
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(15);
+const base = { year: 2000, month: 5, day: 2 };
+
+[Infinity, -Infinity].forEach((inf) => {
+  ["year", "month", "day"].forEach((prop) => {
+    assert.throws(RangeError, () => instance.toPlainDateTime({ ...base, [prop]: inf }), `${prop} property cannot be ${inf}`);
+
+    const calls = [];
+    const obj = TemporalHelpers.toPrimitiveObserver(calls, inf, prop);
+    assert.throws(RangeError, () => instance.toPlainDateTime({ ...base, [prop]: obj }));
+    assert.compareArray(calls, [`get ${prop}.valueOf`, `call ${prop}.valueOf`], "it fails after fetching the primitive value");
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/length.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/length.js
new file mode 100644
index 0000000000..7d480f3993
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/length.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: Temporal.PlainTime.prototype.toPlainDateTime.length is 1
+info: |
+    Every built-in function object, including constructors, has a "length" property whose value is
+    an integer. Unless otherwise specified, this value is equal to the largest number of named
+    arguments shown in the subclause headings for the function description. Optional parameters
+    (which are indicated with brackets: [ ]) or rest parameters (which are shown using the form
+    «...name») are not included in the default argument count.
+
+    Unless otherwise specified, the "length" property of a built-in function object has the
+    attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.toPlainDateTime, "length", {
+  value: 1,
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/limits.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/limits.js
new file mode 100644
index 0000000000..423e019f9f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/limits.js
@@ -0,0 +1,42 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: Checking limits of representable PlainDateTime
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const midnight = new Temporal.PlainTime(0, 0);
+const firstNs = new Temporal.PlainTime(0, 0, 0, 0, 0, 1);
+const lastNs = new Temporal.PlainTime(23, 59, 59, 999, 999, 999);
+const min = new Temporal.PlainDate(-271821, 4, 19);
+const max = new Temporal.PlainDate(275760, 9, 13);
+
+assert.throws(
+  RangeError,
+  () => midnight.toPlainDateTime(min),
+  "Cannot go below representable limit"
+);
+
+TemporalHelpers.assertPlainDateTime(
+  midnight.toPlainDateTime(max),
+  275760, 9, "M09", 13, 0, 0, 0, 0, 0, 0,
+  "Midnight of maximum representable PlainDate"
+);
+
+TemporalHelpers.assertPlainDateTime(
+  firstNs.toPlainDateTime(min),
+  -271821, 4, "M04", 19, 0, 0, 0, 0, 0, 1,
+  "Computing the minimum (earliest) representable PlainDateTime"
+);
+
+TemporalHelpers.assertPlainDateTime(
+  lastNs.toPlainDateTime(max),
+  275760, 9, "M09", 13, 23, 59, 59, 999, 999, 999,
+  "Computing the maximum (latest) representable PlainDateTime"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/name.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/name.js
new file mode 100644
index 0000000000..0b2ee2262e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/name.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: Temporal.PlainTime.prototype.toPlainDateTime.name is "toPlainDateTime".
+info: |
+    Every built-in function object, including constructors, that is not identified as an anonymous
+    function has a "name" property whose value is a String. Unless otherwise specified, this value
+    is the name that is given to the function in this specification.
+
+    Unless otherwise specified, the "name" property of a built-in function object, if it exists,
+    has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.toPlainDateTime, "name", {
+  value: "toPlainDateTime",
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/not-a-constructor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/not-a-constructor.js
new file mode 100644
index 0000000000..feab75d01c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/not-a-constructor.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: >
+  Temporal.PlainTime.prototype.toPlainDateTime does not implement [[Construct]], is not new-able
+info: |
+    Built-in function objects that are not identified as constructors do not implement the
+    [[Construct]] internal method unless otherwise specified in the description of a particular
+    function.
+includes: [isConstructor.js]
+features: [Reflect.construct, Temporal]
+---*/
+
+assert.throws(TypeError, () => {
+  new Temporal.PlainTime.prototype.toPlainDateTime();
+}, "Calling as constructor");
+
+assert.sameValue(isConstructor(Temporal.PlainTime.prototype.toPlainDateTime), false,
+  "isConstructor(Temporal.PlainTime.prototype.toPlainDateTime)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/prop-desc.js
new file mode 100644
index 0000000000..f5259bcc89
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/prop-desc.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: The "toPlainDateTime" property of Temporal.PlainTime.prototype
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+assert.sameValue(
+  typeof Temporal.PlainTime.prototype.toPlainDateTime,
+  "function",
+  "`typeof PlainTime.prototype.toPlainDateTime` is `function`"
+);
+
+verifyProperty(Temporal.PlainTime.prototype, "toPlainDateTime", {
+  writable: true,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/year-zero.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/year-zero.js
new file mode 100644
index 0000000000..8c26d69a57
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toPlainDateTime/year-zero.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.toplaindatetime
+description: Negative zero, as an extended year, is rejected
+features: [Temporal, arrow-function]
+---*/
+
+const invalidStrings = [
+  "-000000-10-31",
+  "-000000-10-31T00:45",
+  "-000000-10-31T00:45+01:00",
+  "-000000-10-31T00:45+00:00[UTC]",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => instance.toPlainDateTime(arg),
+    "reject minus zero as extended year"
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/basic.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/basic.js
new file mode 100644
index 0000000000..9f7b7d56d3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/basic.js
@@ -0,0 +1,18 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: Basic tests for toString()
+features: [Temporal]
+---*/
+
+assert.sameValue(new Temporal.PlainTime(15, 23).toString(), "15:23:00");
+assert.sameValue(new Temporal.PlainTime(15, 23, 30).toString(), "15:23:30");
+assert.sameValue(new Temporal.PlainTime(15, 23, 30, 123).toString(), "15:23:30.123");
+assert.sameValue(new Temporal.PlainTime(15, 23, 30, 123, 400).toString(), "15:23:30.1234");
+assert.sameValue(new Temporal.PlainTime(15, 23, 30, 123, 456).toString(), "15:23:30.123456");
+assert.sameValue(new Temporal.PlainTime(15, 23, 30, 123, 456, 789).toString(), "15:23:30.123456789");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/branding.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/branding.js
new file mode 100644
index 0000000000..1167d4d392
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/branding.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: Throw a TypeError if the receiver is invalid
+features: [Symbol, Temporal]
+---*/
+
+const toString = Temporal.PlainTime.prototype.toString;
+
+assert.sameValue(typeof toString, "function");
+
+assert.throws(TypeError, () => toString.call(undefined), "undefined");
+assert.throws(TypeError, () => toString.call(null), "null");
+assert.throws(TypeError, () => toString.call(true), "true");
+assert.throws(TypeError, () => toString.call(""), "empty string");
+assert.throws(TypeError, () => toString.call(Symbol()), "symbol");
+assert.throws(TypeError, () => toString.call(1), "1");
+assert.throws(TypeError, () => toString.call({}), "plain object");
+assert.throws(TypeError, () => toString.call(Temporal.PlainTime), "Temporal.PlainTime");
+assert.throws(TypeError, () => toString.call(Temporal.PlainTime.prototype), "Temporal.PlainTime.prototype");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/builtin.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/builtin.js
new file mode 100644
index 0000000000..3181b5fbb3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/builtin.js
@@ -0,0 +1,36 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: >
+    Tests that Temporal.PlainTime.prototype.toString
+    meets the requirements for built-in objects defined by the
+    introduction of chapter 17 of the ECMAScript Language Specification.
+info: |
+    Built-in functions that are not constructors do not have a "prototype" property unless
+    otherwise specified in the description of a particular function.
+
+    Unless specified otherwise, a built-in object that is callable as a function is a built-in
+    function object with the characteristics described in 10.3. Unless specified otherwise, the
+    [[Extensible]] internal slot of a built-in object initially has the value true.
+
+    Unless otherwise specified every built-in function and every built-in constructor has the
+    Function prototype object [...] as the value of its [[Prototype]] internal slot.
+features: [Temporal]
+---*/
+
+assert.sameValue(Object.isExtensible(Temporal.PlainTime.prototype.toString),
+  true, "Built-in objects must be extensible.");
+
+assert.sameValue(Object.prototype.toString.call(Temporal.PlainTime.prototype.toString),
+  "[object Function]", "Object.prototype.toString");
+
+assert.sameValue(Object.getPrototypeOf(Temporal.PlainTime.prototype.toString),
+  Function.prototype, "prototype");
+
+assert.sameValue(Temporal.PlainTime.prototype.toString.hasOwnProperty("prototype"),
+  false, "prototype property");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-auto.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-auto.js
new file mode 100644
index 0000000000..68010206f6
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-auto.js
@@ -0,0 +1,23 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: auto value for fractionalSecondDigits option
+features: [Temporal]
+---*/
+
+const tests = [
+  [new Temporal.PlainTime(5, 3, 1), "05:03:01"],
+  [new Temporal.PlainTime(15, 23), "15:23:00"],
+  [new Temporal.PlainTime(15, 23, 30), "15:23:30"],
+  [new Temporal.PlainTime(15, 23, 30, 123, 400), "15:23:30.1234"],
+];
+
+for (const [time, expected] of tests) {
+  assert.sameValue(time.toString(), expected, "default is to emit seconds and drop trailing zeroes");
+  assert.sameValue(time.toString({ fractionalSecondDigits: "auto" }), expected, "auto is the default");
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-invalid-string.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-invalid-string.js
new file mode 100644
index 0000000000..af13900339
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-invalid-string.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: RangeError thrown when fractionalSecondDigits option not one of the allowed string values
+info: |
+    sec-getstringornumberoption step 4:
+      4. If _stringValues_ is not *undefined* and _stringValues_ does not contain an element equal to _value_, throw a *RangeError* exception.
+    sec-temporal-tosecondsstringprecision step 9:
+      9. Let _digits_ be ? GetStringOrNumberOption(_normalizedOptions_, *"fractionalSecondDigits"*, « *"auto"* », 0, 9, *"auto"*).
+    sec-temporal.plaintime.prototype.tostring step 4:
+      4. Let _precision_ be ? ToSecondsStringPrecision(_options_).
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 987, 650, 0);
+
+for (const fractionalSecondDigits of ["other string", "AUTO", "not-auto", "autos", "auto\0"]) {
+  assert.throws(RangeError, () => time.toString({ fractionalSecondDigits }),
+    `"${fractionalSecondDigits}" is not a valid value for fractionalSecondDigits`);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-nan.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-nan.js
new file mode 100644
index 0000000000..10322e548e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-nan.js
@@ -0,0 +1,23 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: RangeError thrown when fractionalSecondDigits option is NaN
+info: |
+    sec-getoption step 8.b:
+      b. If _value_ is *NaN*, throw a *RangeError* exception.
+    sec-getstringornumberoption step 2:
+      2. Let _value_ be ? GetOption(_options_, _property_, « Number, String », *undefined*, _fallback_).
+    sec-temporal-tosecondsstringprecision step 9:
+      9. Let _digits_ be ? GetStringOrNumberOption(_normalizedOptions_, *"fractionalSecondDigits"*, « *"auto"* », 0, 9, *"auto"*).
+    sec-temporal.plaintime.prototype.tostring step 4:
+      4. Let _precision_ be ? ToSecondsStringPrecision(_options_).
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 987, 650, 0);
+assert.throws(RangeError, () => time.toString({ fractionalSecondDigits: NaN }));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-non-integer.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-non-integer.js
new file mode 100644
index 0000000000..4f0da7d505
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-non-integer.js
@@ -0,0 +1,32 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: Rounding for fractionalSecondDigits option
+info: |
+    sec-getstringornumberoption step 3.b:
+      b. Return floor(ℝ(_value_)).
+    sec-temporal-tosecondsstringprecision step 9:
+      9. Let _digits_ be ? GetStringOrNumberOption(_normalizedOptions_, *"fractionalSecondDigits"*, « *"auto"* », 0, 9, *"auto"*).
+    sec-temporal.plaintime.prototype.tostring step 4:
+      4. Let _precision_ be ? ToSecondsStringPrecision(_options_).
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 987, 650, 0);
+
+let string = time.toString({ fractionalSecondDigits: 2.5 });
+assert.sameValue(string, "12:34:56.98", "fractionalSecondDigits 2.5 floors to 2");
+
+string = time.toString({ fractionalSecondDigits: 9.7 });
+assert.sameValue(string, "12:34:56.987650000", "fractionalSecondDigits 9.7 floors to 9 and is not out of range");
+
+assert.throws(
+  RangeError,
+  () => time.toString({ fractionalSecondDigits: -0.6 }),
+  "fractionalSecondDigits -0.6 floors to -1 and is out of range"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-number.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-number.js
new file mode 100644
index 0000000000..ab026470ed
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-number.js
@@ -0,0 +1,39 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: Number for fractionalSecondDigits option
+features: [Temporal]
+---*/
+
+const fewSeconds = new Temporal.PlainTime(5, 3, 1);
+const zeroSeconds = new Temporal.PlainTime(15, 23);
+const wholeSeconds = new Temporal.PlainTime(15, 23, 30);
+const subSeconds = new Temporal.PlainTime(15, 23, 30, 123, 400);
+
+assert.sameValue(fewSeconds.toString({ fractionalSecondDigits: 0 }), "05:03:01",
+  "pads parts with 0");
+assert.sameValue(subSeconds.toString({ fractionalSecondDigits: 0 }), "15:23:30",
+  "truncates 4 decimal places to 0");
+assert.sameValue(zeroSeconds.toString({ fractionalSecondDigits: 2 }), "15:23:00.00",
+  "pads zero seconds to 2 decimal places");
+assert.sameValue(wholeSeconds.toString({ fractionalSecondDigits: 2 }), "15:23:30.00",
+  "pads whole seconds to 2 decimal places");
+assert.sameValue(subSeconds.toString({ fractionalSecondDigits: 2 }), "15:23:30.12",
+  "truncates 4 decimal places to 2");
+assert.sameValue(subSeconds.toString({ fractionalSecondDigits: 3 }), "15:23:30.123",
+  "truncates 4 decimal places to 3");
+assert.sameValue(subSeconds.toString({ fractionalSecondDigits: 6 }), "15:23:30.123400",
+  "pads 4 decimal places to 6");
+assert.sameValue(zeroSeconds.toString({ fractionalSecondDigits: 7 }), "15:23:00.0000000",
+  "pads zero seconds to 7 decimal places");
+assert.sameValue(wholeSeconds.toString({ fractionalSecondDigits: 7 }), "15:23:30.0000000",
+  "pads whole seconds to 7 decimal places");
+assert.sameValue(subSeconds.toString({ fractionalSecondDigits: 7 }), "15:23:30.1234000",
+  "pads 4 decimal places to 7");
+assert.sameValue(subSeconds.toString({ fractionalSecondDigits: 9 }), "15:23:30.123400000",
+  "pads 4 decimal places to 9");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-out-of-range.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-out-of-range.js
new file mode 100644
index 0000000000..c58e35a3da
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-out-of-range.js
@@ -0,0 +1,29 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: RangeError thrown when fractionalSecondDigits option out of range
+info: |
+    sec-getstringornumberoption step 3.a:
+      a. If _value_ < _minimum_ or _value_ > _maximum_, throw a *RangeError* exception.
+    sec-temporal-tosecondsstringprecision step 9:
+      9. Let _digits_ be ? GetStringOrNumberOption(_normalizedOptions_, *"fractionalSecondDigits"*, « *"auto"* », 0, 9, *"auto"*).
+    sec-temporal.plaintime.prototype.tostring step 4:
+      4. Let _precision_ be ? ToSecondsStringPrecision(_options_).
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 987, 650, 0);
+
+assert.throws(RangeError, () => time.toString({ fractionalSecondDigits: -Infinity }),
+  "−∞ is out of range for fractionalSecondDigits");
+assert.throws(RangeError, () => time.toString({ fractionalSecondDigits: -1 }),
+  "−1 is out of range for fractionalSecondDigits");
+assert.throws(RangeError, () => time.toString({ fractionalSecondDigits: 10 }),
+  "10 is out of range for fractionalSecondDigits");
+assert.throws(RangeError, () => time.toString({ fractionalSecondDigits: Infinity }),
+  "∞ is out of range for fractionalSecondDigits");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-undefined.js
new file mode 100644
index 0000000000..778f98848e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-undefined.js
@@ -0,0 +1,38 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: Fallback value for fractionalSecondDigits option
+info: |
+    sec-getoption step 3:
+      3. If _value_ is *undefined*, return _fallback_.
+    sec-getstringornumberoption step 2:
+      2. Let _value_ be ? GetOption(_options_, _property_, « Number, String », *undefined*, _fallback_).
+    sec-temporal-tosecondsstringprecision step 9:
+      9. Let _digits_ be ? GetStringOrNumberOption(_normalizedOptions_, *"fractionalSecondDigits"*, « *"auto"* », 0, 9, *"auto"*).
+    sec-temporal.plaintime.prototype.tostring step 4:
+      4. Let _precision_ be ? ToSecondsStringPrecision(_options_).
+features: [Temporal]
+---*/
+
+const tests = [
+  [new Temporal.PlainTime(5, 3, 1), "05:03:01"],
+  [new Temporal.PlainTime(15, 23), "15:23:00"],
+  [new Temporal.PlainTime(15, 23, 30), "15:23:30"],
+  [new Temporal.PlainTime(15, 23, 30, 123, 400), "15:23:30.1234"],
+];
+
+for (const [time, expected] of tests) {
+  const explicit = time.toString({ fractionalSecondDigits: undefined });
+  assert.sameValue(explicit, expected, "default fractionalSecondDigits is auto (property present but undefined)");
+
+  const implicit = time.toString({});
+  assert.sameValue(implicit, expected, "default fractionalSecondDigits is auto (property not present)");
+
+  const lambda = time.toString(() => {});
+  assert.sameValue(lambda, expected, "default fractionalSecondDigits is auto (property not present, function object)");
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-wrong-type.js
new file mode 100644
index 0000000000..4c7bffaf2e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-wrong-type.js
@@ -0,0 +1,50 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: Type conversions for fractionalSecondDigits option
+info: |
+    sec-getoption steps 8–9:
+      8. Else if _type_ is Number, then
+        a. Set _value_ to ? ToNumber(value).
+        b. ...
+      9. Else,
+        a. Set _value_ to ? ToString(value).
+    sec-getstringornumberoption step 2:
+      2. Let _value_ be ? GetOption(_options_, _property_, « Number, String », *undefined*, _fallback_).
+    sec-temporal-tosecondsstringprecision step 9:
+      9. Let _digits_ be ? GetStringOrNumberOption(_normalizedOptions_, *"fractionalSecondDigits"*, « *"auto"* », 0, 9, *"auto"*).
+    sec-temporal.plaintime.prototype.tostring step 4:
+      4. Let _precision_ be ? ToSecondsStringPrecision(_options_).
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 987, 650, 0);
+
+assert.throws(RangeError, () => time.toString({ fractionalSecondDigits: null }),
+  "null is not a number and converts to the string 'null' which is not valid for fractionalSecondDigits");
+assert.throws(RangeError, () => time.toString({ fractionalSecondDigits: true }),
+  "true is not a number and converts to the string 'true' which is not valid for fractionalSecondDigits");
+assert.throws(RangeError, () => time.toString({ fractionalSecondDigits: false }),
+  "false is not a number and converts to the string 'false' which is not valid for fractionalSecondDigits");
+assert.throws(TypeError, () => time.toString({ fractionalSecondDigits: Symbol() }),
+  "symbols are not numbers and cannot convert to strings");
+assert.throws(RangeError, () => time.toString({ fractionalSecondDigits: 2n }),
+  "bigints are not numbers and convert to strings which are not valid for fractionalSecondDigits");
+assert.throws(RangeError, () => time.toString({ fractionalSecondDigits: {} }),
+  "plain objects are not numbers and convert to strings which are not valid for fractionalSecondDigits");
+
+const expected = [
+  "get fractionalSecondDigits.toString",
+  "call fractionalSecondDigits.toString",
+];
+const actual = [];
+const observer = TemporalHelpers.toPrimitiveObserver(actual, "auto", "fractionalSecondDigits");
+const result = time.toString({ fractionalSecondDigits: observer });
+assert.sameValue(result, "12:34:56.98765", "object with toString uses toString return value");
+assert.compareArray(actual, expected, "object with toString calls toString and not valueOf");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/length.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/length.js
new file mode 100644
index 0000000000..6cec084834
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/length.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: Temporal.PlainTime.prototype.toString.length is 0
+info: |
+    Every built-in function object, including constructors, has a "length" property whose value is
+    an integer. Unless otherwise specified, this value is equal to the largest number of named
+    arguments shown in the subclause headings for the function description. Optional parameters
+    (which are indicated with brackets: [ ]) or rest parameters (which are shown using the form
+    «...name») are not included in the default argument count.
+
+    Unless otherwise specified, the "length" property of a built-in function object has the
+    attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.toString, "length", {
+  value: 0,
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/name.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/name.js
new file mode 100644
index 0000000000..779870e99c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/name.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: Temporal.PlainTime.prototype.toString.name is "toString".
+info: |
+    Every built-in function object, including constructors, that is not identified as an anonymous
+    function has a "name" property whose value is a String. Unless otherwise specified, this value
+    is the name that is given to the function in this specification.
+
+    Unless otherwise specified, the "name" property of a built-in function object, if it exists,
+    has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.toString, "name", {
+  value: "toString",
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/not-a-constructor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/not-a-constructor.js
new file mode 100644
index 0000000000..63cbd85a17
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/not-a-constructor.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: >
+  Temporal.PlainTime.prototype.toString does not implement [[Construct]], is not new-able
+info: |
+    Built-in function objects that are not identified as constructors do not implement the
+    [[Construct]] internal method unless otherwise specified in the description of a particular
+    function.
+includes: [isConstructor.js]
+features: [Reflect.construct, Temporal]
+---*/
+
+assert.throws(TypeError, () => {
+  new Temporal.PlainTime.prototype.toString();
+}, "Calling as constructor");
+
+assert.sameValue(isConstructor(Temporal.PlainTime.prototype.toString), false,
+  "isConstructor(Temporal.PlainTime.prototype.toString)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/options-invalid.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/options-invalid.js
new file mode 100644
index 0000000000..369e679f35
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/options-invalid.js
@@ -0,0 +1,18 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: TypeError thrown when a primitive is passed as the options argument
+features: [Temporal]
+---*/
+
+const instance = Temporal.PlainTime.from("12:56:32");
+const values = [null, true, "hello", Symbol("foo"), 1, 1n];
+
+for (const badOptions of values) {
+  assert.throws(TypeError, () => instance.toString(badOptions));
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/options-object.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/options-object.js
new file mode 100644
index 0000000000..f5aa9b164f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/options-object.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: Empty or a function object may be used as options
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime();
+
+const result1 = instance.toString({});
+assert.sameValue(
+  result1, "00:00:00",
+  "options may be an empty plain object"
+);
+
+const result2 = instance.toString(() => {});
+assert.sameValue(
+  result2, "00:00:00",
+  "options may be a function object"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/options-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/options-undefined.js
new file mode 100644
index 0000000000..bf5e2f9e02
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/options-undefined.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: Verify that undefined options are handled correctly.
+features: [Temporal]
+---*/
+
+const tests = [
+  ["15:23", "15:23:00"],
+  ["15:23:30", "15:23:30"],
+  ["15:23:30.1234", "15:23:30.1234"],
+];
+
+for (const [input, expected] of tests) {
+  const time = Temporal.PlainTime.from(input);
+
+  const explicit = time.toString(undefined);
+  assert.sameValue(explicit, expected, "default precision is auto and no rounding");
+
+  const implicit = time.toString();
+  assert.sameValue(implicit, expected, "default precision is auto and no rounding");
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/options-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/options-wrong-type.js
new file mode 100644
index 0000000000..40343e1cc4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/options-wrong-type.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: TypeError thrown when options argument is a primitive
+features: [BigInt, Symbol, Temporal]
+---*/
+
+const badOptions = [
+  null,
+  true,
+  "some string",
+  Symbol(),
+  1,
+  2n,
+];
+
+const instance = new Temporal.PlainTime();
+for (const value of badOptions) {
+  assert.throws(TypeError, () => instance.toString(value),
+    `TypeError on wrong options type ${typeof value}`);
+};
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/order-of-operations.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/order-of-operations.js
new file mode 100644
index 0000000000..2a74c0cfd3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/order-of-operations.js
@@ -0,0 +1,49 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: Properties on objects passed to toString() are accessed in the correct order
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const expected = [
+  "get options.fractionalSecondDigits",
+  "get options.fractionalSecondDigits.toString",
+  "call options.fractionalSecondDigits.toString",
+  "get options.roundingMode",
+  "get options.roundingMode.toString",
+  "call options.roundingMode.toString",
+  "get options.smallestUnit",
+];
+const actual = [];
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const expectedForSmallestUnit = expected.concat([
+  "get options.smallestUnit.toString",
+  "call options.smallestUnit.toString",
+]);
+
+instance.toString(
+  TemporalHelpers.propertyBagObserver(actual, {
+    fractionalSecondDigits: "auto",
+    roundingMode: "halfExpand",
+    smallestUnit: "millisecond",
+  }, "options"),
+);
+assert.compareArray(actual, expectedForSmallestUnit, "order of operations");
+actual.splice(0); // clear
+
+instance.toString(
+  TemporalHelpers.propertyBagObserver(actual, {
+    fractionalSecondDigits: "auto",
+    roundingMode: "halfExpand",
+    smallestUnit: undefined,
+  }, "options"),
+);
+assert.compareArray(actual, expected, "order of operations with smallestUnit undefined");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/prop-desc.js
new file mode 100644
index 0000000000..483fac8d9e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/prop-desc.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: The "toString" property of Temporal.PlainTime.prototype
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+assert.sameValue(
+  typeof Temporal.PlainTime.prototype.toString,
+  "function",
+  "`typeof PlainTime.prototype.toString` is `function`"
+);
+
+verifyProperty(Temporal.PlainTime.prototype, "toString", {
+  writable: true,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/rounding-cross-midnight.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/rounding-cross-midnight.js
new file mode 100644
index 0000000000..c1b6961118
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/rounding-cross-midnight.js
@@ -0,0 +1,16 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: Rounding can cross midnight
+features: [Temporal]
+---*/
+
+const plainTime = new Temporal.PlainTime(23, 59, 59, 999, 999, 999);  // one nanosecond before 00:00:00
+for (const roundingMode of ["ceil", "halfExpand"]) {
+  assert.sameValue(plainTime.toString({ fractionalSecondDigits: 8, roundingMode }), "00:00:00.00000000");
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-ceil.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-ceil.js
new file mode 100644
index 0000000000..533d7a2375
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-ceil.js
@@ -0,0 +1,40 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: ceil value for roundingMode option
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 123, 987, 500);
+
+const result1 = time.toString({ smallestUnit: "microsecond", roundingMode: "ceil" });
+assert.sameValue(result1, "12:34:56.123988",
+  "roundingMode is ceil (with 6 digits from smallestUnit)");
+
+const result2 = time.toString({ fractionalSecondDigits: 6, roundingMode: "ceil" });
+assert.sameValue(result2, "12:34:56.123988",
+  "roundingMode is ceil (with 6 digits from fractionalSecondDigits)");
+
+const result3 = time.toString({ smallestUnit: "millisecond", roundingMode: "ceil" });
+assert.sameValue(result3, "12:34:56.124",
+  "roundingMode is ceil (with 3 digits from smallestUnit)");
+
+const result4 = time.toString({ fractionalSecondDigits: 3, roundingMode: "ceil" });
+assert.sameValue(result4, "12:34:56.124",
+  "roundingMode is ceil (with 3 digits from fractionalSecondDigits)");
+
+const result5 = time.toString({ smallestUnit: "second", roundingMode: "ceil" });
+assert.sameValue(result5, "12:34:57",
+  "roundingMode is ceil (with 0 digits from smallestUnit)");
+
+const result6 = time.toString({ fractionalSecondDigits: 0, roundingMode: "ceil" });
+assert.sameValue(result6, "12:34:57",
+  "roundingMode is ceil (with 0 digits from fractionalSecondDigits)");
+
+const result7 = time.toString({ smallestUnit: "minute", roundingMode: "ceil" });
+assert.sameValue(result7, "12:35", "roundingMode is ceil (round to minute)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-expand.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-expand.js
new file mode 100644
index 0000000000..3b9357e051
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-expand.js
@@ -0,0 +1,40 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: expand value for roundingMode option
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 123, 987, 500);
+
+const result1 = time.toString({ smallestUnit: "microsecond", roundingMode: "expand" });
+assert.sameValue(result1, "12:34:56.123988",
+  "roundingMode is expand (with 6 digits from smallestUnit)");
+
+const result2 = time.toString({ fractionalSecondDigits: 6, roundingMode: "expand" });
+assert.sameValue(result2, "12:34:56.123988",
+  "roundingMode is expand (with 6 digits from fractionalSecondDigits)");
+
+const result3 = time.toString({ smallestUnit: "millisecond", roundingMode: "expand" });
+assert.sameValue(result3, "12:34:56.124",
+  "roundingMode is expand (with 3 digits from smallestUnit)");
+
+const result4 = time.toString({ fractionalSecondDigits: 3, roundingMode: "expand" });
+assert.sameValue(result4, "12:34:56.124",
+  "roundingMode is expand (with 3 digits from fractionalSecondDigits)");
+
+const result5 = time.toString({ smallestUnit: "second", roundingMode: "expand" });
+assert.sameValue(result5, "12:34:57",
+  "roundingMode is expand (with 0 digits from smallestUnit)");
+
+const result6 = time.toString({ fractionalSecondDigits: 0, roundingMode: "expand" });
+assert.sameValue(result6, "12:34:57",
+  "roundingMode is expand (with 0 digits from fractionalSecondDigits)");
+
+const result7 = time.toString({ smallestUnit: "minute", roundingMode: "expand" });
+assert.sameValue(result7, "12:35", "roundingMode is expand (round to minute)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-floor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-floor.js
new file mode 100644
index 0000000000..d885cb9b1f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-floor.js
@@ -0,0 +1,40 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: floor value for roundingMode option
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 123, 987, 500);
+
+const result1 = time.toString({ smallestUnit: "microsecond", roundingMode: "floor" });
+assert.sameValue(result1, "12:34:56.123987",
+  "roundingMode is floor (with 6 digits from smallestUnit)");
+
+const result2 = time.toString({ fractionalSecondDigits: 6, roundingMode: "floor" });
+assert.sameValue(result2, "12:34:56.123987",
+  "roundingMode is floor (with 6 digits from fractionalSecondDigits)");
+
+const result3 = time.toString({ smallestUnit: "millisecond", roundingMode: "floor" });
+assert.sameValue(result3, "12:34:56.123",
+  "roundingMode is floor (with 3 digits from smallestUnit)");
+
+const result4 = time.toString({ fractionalSecondDigits: 3, roundingMode: "floor" });
+assert.sameValue(result4, "12:34:56.123",
+  "roundingMode is floor (with 3 digits from fractionalSecondDigits)");
+
+const result5 = time.toString({ smallestUnit: "second", roundingMode: "floor" });
+assert.sameValue(result5, "12:34:56",
+  "roundingMode is floor (with 0 digits from smallestUnit)");
+
+const result6 = time.toString({ fractionalSecondDigits: 0, roundingMode: "floor" });
+assert.sameValue(result6, "12:34:56",
+  "roundingMode is floor (with 0 digits from fractionalSecondDigits)");
+
+const result7 = time.toString({ smallestUnit: "minute", roundingMode: "floor" });
+assert.sameValue(result7, "12:34", "roundingMode is floor (round to minute)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-halfCeil.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-halfCeil.js
new file mode 100644
index 0000000000..2e8afe9023
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-halfCeil.js
@@ -0,0 +1,40 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: halfCeil value for roundingMode option
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 123, 987, 500);
+
+const result1 = time.toString({ smallestUnit: "microsecond", roundingMode: "halfCeil" });
+assert.sameValue(result1, "12:34:56.123988",
+  "roundingMode is halfCeil (with 6 digits from smallestUnit)");
+
+const result2 = time.toString({ fractionalSecondDigits: 6, roundingMode: "halfCeil" });
+assert.sameValue(result2, "12:34:56.123988",
+  "roundingMode is halfCeil (with 6 digits from fractionalSecondDigits)");
+
+const result3 = time.toString({ smallestUnit: "millisecond", roundingMode: "halfCeil" });
+assert.sameValue(result3, "12:34:56.124",
+  "roundingMode is halfCeil (with 3 digits from smallestUnit)");
+
+const result4 = time.toString({ fractionalSecondDigits: 3, roundingMode: "halfCeil" });
+assert.sameValue(result4, "12:34:56.124",
+  "roundingMode is halfCeil (with 3 digits from fractionalSecondDigits)");
+
+const result5 = time.toString({ smallestUnit: "second", roundingMode: "halfCeil" });
+assert.sameValue(result5, "12:34:56",
+  "roundingMode is halfCeil (with 0 digits from smallestUnit)");
+
+const result6 = time.toString({ fractionalSecondDigits: 0, roundingMode: "halfCeil" });
+assert.sameValue(result6, "12:34:56",
+  "roundingMode is halfCeil (with 0 digits from fractionalSecondDigits)");
+
+const result7 = time.toString({ smallestUnit: "minute", roundingMode: "halfCeil" });
+assert.sameValue(result7, "12:35", "roundingMode is halfCeil (round to minute)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-halfEven.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-halfEven.js
new file mode 100644
index 0000000000..d58bc166dc
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-halfEven.js
@@ -0,0 +1,40 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: halfEven value for roundingMode option
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 123, 987, 500);
+
+const result1 = time.toString({ smallestUnit: "microsecond", roundingMode: "halfEven" });
+assert.sameValue(result1, "12:34:56.123988",
+  "roundingMode is halfEven (with 6 digits from smallestUnit)");
+
+const result2 = time.toString({ fractionalSecondDigits: 6, roundingMode: "halfEven" });
+assert.sameValue(result2, "12:34:56.123988",
+  "roundingMode is halfEven (with 6 digits from fractionalSecondDigits)");
+
+const result3 = time.toString({ smallestUnit: "millisecond", roundingMode: "halfEven" });
+assert.sameValue(result3, "12:34:56.124",
+  "roundingMode is halfEven (with 3 digits from smallestUnit)");
+
+const result4 = time.toString({ fractionalSecondDigits: 3, roundingMode: "halfEven" });
+assert.sameValue(result4, "12:34:56.124",
+  "roundingMode is halfEven (with 3 digits from fractionalSecondDigits)");
+
+const result5 = time.toString({ smallestUnit: "second", roundingMode: "halfEven" });
+assert.sameValue(result5, "12:34:56",
+  "roundingMode is halfEven (with 0 digits from smallestUnit)");
+
+const result6 = time.toString({ fractionalSecondDigits: 0, roundingMode: "halfEven" });
+assert.sameValue(result6, "12:34:56",
+  "roundingMode is halfEven (with 0 digits from fractionalSecondDigits)");
+
+const result7 = time.toString({ smallestUnit: "minute", roundingMode: "halfEven" });
+assert.sameValue(result7, "12:35", "roundingMode is halfEven (round to minute)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-halfExpand.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-halfExpand.js
new file mode 100644
index 0000000000..72c287004f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-halfExpand.js
@@ -0,0 +1,40 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: halfExpand value for roundingMode option
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 123, 987, 500);
+
+const result1 = time.toString({ smallestUnit: "microsecond", roundingMode: "halfExpand" });
+assert.sameValue(result1, "12:34:56.123988",
+  "roundingMode is halfExpand (with 6 digits from smallestUnit)");
+
+const result2 = time.toString({ fractionalSecondDigits: 6, roundingMode: "halfExpand" });
+assert.sameValue(result2, "12:34:56.123988",
+  "roundingMode is halfExpand (with 6 digits from fractionalSecondDigits)");
+
+const result3 = time.toString({ smallestUnit: "millisecond", roundingMode: "halfExpand" });
+assert.sameValue(result3, "12:34:56.124",
+  "roundingMode is halfExpand (with 3 digits from smallestUnit)");
+
+const result4 = time.toString({ fractionalSecondDigits: 3, roundingMode: "halfExpand" });
+assert.sameValue(result4, "12:34:56.124",
+  "roundingMode is halfExpand (with 3 digits from fractionalSecondDigits)");
+
+const result5 = time.toString({ smallestUnit: "second", roundingMode: "halfExpand" });
+assert.sameValue(result5, "12:34:56",
+  "roundingMode is halfExpand (with 0 digits from smallestUnit)");
+
+const result6 = time.toString({ fractionalSecondDigits: 0, roundingMode: "halfExpand" });
+assert.sameValue(result6, "12:34:56",
+  "roundingMode is halfExpand (with 0 digits from fractionalSecondDigits)");
+
+const result7 = time.toString({ smallestUnit: "minute", roundingMode: "halfExpand" });
+assert.sameValue(result7, "12:35", "roundingMode is halfExpand (round to minute)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-halfFloor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-halfFloor.js
new file mode 100644
index 0000000000..ce18435ed6
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-halfFloor.js
@@ -0,0 +1,40 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: halfFloor value for roundingMode option
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 123, 987, 500);
+
+const result1 = time.toString({ smallestUnit: "microsecond", roundingMode: "halfFloor" });
+assert.sameValue(result1, "12:34:56.123987",
+  "roundingMode is halfFloor (with 6 digits from smallestUnit)");
+
+const result2 = time.toString({ fractionalSecondDigits: 6, roundingMode: "halfFloor" });
+assert.sameValue(result2, "12:34:56.123987",
+  "roundingMode is halfFloor (with 6 digits from fractionalSecondDigits)");
+
+const result3 = time.toString({ smallestUnit: "millisecond", roundingMode: "halfFloor" });
+assert.sameValue(result3, "12:34:56.124",
+  "roundingMode is halfFloor (with 3 digits from smallestUnit)");
+
+const result4 = time.toString({ fractionalSecondDigits: 3, roundingMode: "halfFloor" });
+assert.sameValue(result4, "12:34:56.124",
+  "roundingMode is halfFloor (with 3 digits from fractionalSecondDigits)");
+
+const result5 = time.toString({ smallestUnit: "second", roundingMode: "halfFloor" });
+assert.sameValue(result5, "12:34:56",
+  "roundingMode is halfFloor (with 0 digits from smallestUnit)");
+
+const result6 = time.toString({ fractionalSecondDigits: 0, roundingMode: "halfFloor" });
+assert.sameValue(result6, "12:34:56",
+  "roundingMode is halfFloor (with 0 digits from fractionalSecondDigits)");
+
+const result7 = time.toString({ smallestUnit: "minute", roundingMode: "halfFloor" });
+assert.sameValue(result7, "12:35", "roundingMode is halfFloor (round to minute)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-halfTrunc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-halfTrunc.js
new file mode 100644
index 0000000000..c41d7b8144
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-halfTrunc.js
@@ -0,0 +1,40 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: halfTrunc value for roundingMode option
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 123, 987, 500);
+
+const result1 = time.toString({ smallestUnit: "microsecond", roundingMode: "halfTrunc" });
+assert.sameValue(result1, "12:34:56.123987",
+  "roundingMode is halfTrunc (with 6 digits from smallestUnit)");
+
+const result2 = time.toString({ fractionalSecondDigits: 6, roundingMode: "halfTrunc" });
+assert.sameValue(result2, "12:34:56.123987",
+  "roundingMode is halfTrunc (with 6 digits from fractionalSecondDigits)");
+
+const result3 = time.toString({ smallestUnit: "millisecond", roundingMode: "halfTrunc" });
+assert.sameValue(result3, "12:34:56.124",
+  "roundingMode is halfTrunc (with 3 digits from smallestUnit)");
+
+const result4 = time.toString({ fractionalSecondDigits: 3, roundingMode: "halfTrunc" });
+assert.sameValue(result4, "12:34:56.124",
+  "roundingMode is halfTrunc (with 3 digits from fractionalSecondDigits)");
+
+const result5 = time.toString({ smallestUnit: "second", roundingMode: "halfTrunc" });
+assert.sameValue(result5, "12:34:56",
+  "roundingMode is halfTrunc (with 0 digits from smallestUnit)");
+
+const result6 = time.toString({ fractionalSecondDigits: 0, roundingMode: "halfTrunc" });
+assert.sameValue(result6, "12:34:56",
+  "roundingMode is halfTrunc (with 0 digits from fractionalSecondDigits)");
+
+const result7 = time.toString({ smallestUnit: "minute", roundingMode: "halfTrunc" });
+assert.sameValue(result7, "12:35", "roundingMode is halfTrunc (round to minute)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-invalid-string.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-invalid-string.js
new file mode 100644
index 0000000000..8a708fe139
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-invalid-string.js
@@ -0,0 +1,16 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: RangeError thrown when roundingMode option not one of the allowed string values
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 123, 987, 500);
+for (const roundingMode of ["other string", "cile", "CEIL", "ce\u0131l", "auto", "halfexpand", "floor\0"]) {
+  assert.throws(RangeError, () => time.toString({ smallestUnit: "microsecond", roundingMode }));
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-trunc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-trunc.js
new file mode 100644
index 0000000000..7951487e47
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-trunc.js
@@ -0,0 +1,40 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: trunc value for roundingMode option
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 123, 987, 500);
+
+const result1 = time.toString({ smallestUnit: "microsecond", roundingMode: "trunc" });
+assert.sameValue(result1, "12:34:56.123987",
+  "roundingMode is trunc (with 6 digits from smallestUnit)");
+
+const result2 = time.toString({ fractionalSecondDigits: 6, roundingMode: "trunc" });
+assert.sameValue(result2, "12:34:56.123987",
+  "roundingMode is trunc (with 6 digits from fractionalSecondDigits)");
+
+const result3 = time.toString({ smallestUnit: "millisecond", roundingMode: "trunc" });
+assert.sameValue(result3, "12:34:56.123",
+  "roundingMode is trunc (with 3 digits from smallestUnit)");
+
+const result4 = time.toString({ fractionalSecondDigits: 3, roundingMode: "trunc" });
+assert.sameValue(result4, "12:34:56.123",
+  "roundingMode is trunc (with 3 digits from fractionalSecondDigits)");
+
+const result5 = time.toString({ smallestUnit: "second", roundingMode: "trunc" });
+assert.sameValue(result5, "12:34:56",
+  "roundingMode is trunc (with 0 digits from smallestUnit)");
+
+const result6 = time.toString({ fractionalSecondDigits: 0, roundingMode: "trunc" });
+assert.sameValue(result6, "12:34:56",
+  "roundingMode is trunc (with 0 digits from fractionalSecondDigits)");
+
+const result7 = time.toString({ smallestUnit: "minute", roundingMode: "trunc" });
+assert.sameValue(result7, "12:34", "roundingMode is trunc (round to minute)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-undefined.js
new file mode 100644
index 0000000000..6ec201a3b8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-undefined.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: Fallback value for roundingMode option
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 123, 987, 500);
+
+const explicit1 = time.toString({ smallestUnit: "microsecond", roundingMode: undefined });
+assert.sameValue(explicit1, "12:34:56.123987", "default roundingMode is trunc");
+const implicit1 = time.toString({ smallestUnit: "microsecond" });
+assert.sameValue(implicit1, "12:34:56.123987", "default roundingMode is trunc");
+
+const explicit2 = time.toString({ smallestUnit: "millisecond", roundingMode: undefined });
+assert.sameValue(explicit2, "12:34:56.123", "default roundingMode is trunc");
+const implicit2 = time.toString({ smallestUnit: "millisecond" });
+assert.sameValue(implicit2, "12:34:56.123", "default roundingMode is trunc");
+
+const explicit3 = time.toString({ smallestUnit: "second", roundingMode: undefined });
+assert.sameValue(explicit3, "12:34:56", "default roundingMode is trunc");
+const implicit3 = time.toString({ smallestUnit: "second" });
+assert.sameValue(implicit3, "12:34:56", "default roundingMode is trunc");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-wrong-type.js
new file mode 100644
index 0000000000..47bef2495c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/roundingmode-wrong-type.js
@@ -0,0 +1,18 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: Type conversions for roundingMode option
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 123, 987, 500);
+TemporalHelpers.checkStringOptionWrongType("roundingMode", "trunc",
+  (roundingMode) => time.toString({ smallestUnit: "microsecond", roundingMode }),
+  (result, descr) => assert.sameValue(result, "12:34:56.123987", descr),
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/smallestunit-fractionalseconddigits.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/smallestunit-fractionalseconddigits.js
new file mode 100644
index 0000000000..c436e099ab
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/smallestunit-fractionalseconddigits.js
@@ -0,0 +1,33 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: fractionalSecondDigits option is not used with smallestUnit present
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 789, 999, 999);
+const tests = [
+  ["minute", "12:34"],
+  ["second", "12:34:56"],
+  ["millisecond", "12:34:56.789"],
+  ["microsecond", "12:34:56.789999"],
+  ["nanosecond", "12:34:56.789999999"],
+];
+
+for (const [smallestUnit, expected] of tests) {
+  const string = time.toString({
+    smallestUnit,
+    fractionalSecondDigits: 5,
+  });
+  assert.sameValue(string, expected, `smallestUnit: "${smallestUnit}" overrides fractionalSecondDigits`);
+}
+
+assert.throws(RangeError, () => time.toString({
+  smallestUnit: "hour",
+  fractionalSecondDigits: 5,
+}), "hour is an invalid smallestUnit but still overrides fractionalSecondDigits");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/smallestunit-invalid-string.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/smallestunit-invalid-string.js
new file mode 100644
index 0000000000..70b60a9091
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/smallestunit-invalid-string.js
@@ -0,0 +1,40 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: RangeError thrown when smallestUnit option not one of the allowed string values
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 123, 987, 500);
+const badValues = [
+  "era",
+  "eraYear",
+  "year",
+  "month",
+  "week",
+  "day",
+  "hour",
+  "millisecond\0",
+  "mill\u0131second",
+  "SECOND",
+  "eras",
+  "eraYears",
+  "years",
+  "months",
+  "weeks",
+  "days",
+  "hours",
+  "milliseconds\0",
+  "mill\u0131seconds",
+  "SECONDS",
+  "other string",
+];
+for (const smallestUnit of badValues) {
+  assert.throws(RangeError, () => time.toString({ smallestUnit }),
+    `"${smallestUnit}" is not a valid value for smallest unit`);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/smallestunit-plurals-accepted.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/smallestunit-plurals-accepted.js
new file mode 100644
index 0000000000..4be152fae9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/smallestunit-plurals-accepted.js
@@ -0,0 +1,22 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: Plural units are accepted as well for the smallestUnit option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 789, 999, 999);
+const validUnits = [
+  "minute",
+  "second",
+  "millisecond",
+  "microsecond",
+  "nanosecond",
+];
+TemporalHelpers.checkPluralUnitsAccepted((smallestUnit) => time.toString({ smallestUnit }), validUnits);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/smallestunit-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/smallestunit-undefined.js
new file mode 100644
index 0000000000..3822faf567
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/smallestunit-undefined.js
@@ -0,0 +1,23 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: Fallback value for smallestUnit option
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 123, 987, 500);
+
+const explicit1 = time.toString({ smallestUnit: undefined, fractionalSecondDigits: 6 });
+assert.sameValue(explicit1, "12:34:56.123987", "default smallestUnit defers to fractionalSecondDigits");
+const implicit1 = time.toString({ fractionalSecondDigits: 6 });
+assert.sameValue(implicit1, "12:34:56.123987", "default smallestUnit defers to fractionalSecondDigits");
+
+const explicit2 = time.toString({ smallestUnit: undefined, fractionalSecondDigits: 3 });
+assert.sameValue(explicit2, "12:34:56.123", "default smallestUnit defers to fractionalSecondDigits");
+const implicit2 = time.toString({ fractionalSecondDigits: 3 });
+assert.sameValue(implicit2, "12:34:56.123", "default smallestUnit defers to fractionalSecondDigits");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/smallestunit-valid-units.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/smallestunit-valid-units.js
new file mode 100644
index 0000000000..825680c0ff
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/smallestunit-valid-units.js
@@ -0,0 +1,58 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: Valid units for the smallestUnit option
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 123, 456, 789);
+
+function test(instance, expectations, description) {
+  for (const [smallestUnit, expectedResult] of expectations) {
+    assert.sameValue(instance.toString({ smallestUnit }), expectedResult,
+      `${description} with smallestUnit "${smallestUnit}"`);
+  }
+}
+
+test(
+  time,
+  [
+    ["minute", "12:34"],
+    ["second", "12:34:56"],
+    ["millisecond", "12:34:56.123"],
+    ["microsecond", "12:34:56.123456"],
+    ["nanosecond", "12:34:56.123456789"],
+  ],
+  "subseconds toString"
+);
+
+test(
+  new Temporal.PlainTime(12, 34),
+  [
+    ["minute", "12:34"],
+    ["second", "12:34:00"],
+    ["millisecond", "12:34:00.000"],
+    ["microsecond", "12:34:00.000000"],
+    ["nanosecond", "12:34:00.000000000"],
+  ],
+  "whole minutes toString"
+);
+
+const notValid = [
+  "era",
+  "year",
+  "month",
+  "week",
+  "day",
+  "hour",
+];
+
+notValid.forEach((smallestUnit) => {
+  assert.throws(RangeError, () => time.toString({ smallestUnit }),
+    `"${smallestUnit}" is not a valid unit for the smallestUnit option`);
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/smallestunit-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/smallestunit-wrong-type.js
new file mode 100644
index 0000000000..777877c8bb
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toString/smallestunit-wrong-type.js
@@ -0,0 +1,18 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tostring
+description: Type conversions for smallestUnit option
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 123, 987, 500);
+TemporalHelpers.checkStringOptionWrongType("smallestUnit", "microsecond",
+  (smallestUnit) => time.toString({ smallestUnit }),
+  (result, descr) => assert.sameValue(result, "12:34:56.123987", descr),
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toStringTag/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toStringTag/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toStringTag/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toStringTag/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toStringTag/prop-desc.js
new file mode 100644
index 0000000000..791343f67f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toStringTag/prop-desc.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype-@@tostringtag
+description: The @@toStringTag property of Temporal.PlainTime
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype, Symbol.toStringTag, {
+  value: "Temporal.PlainTime",
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toStringTag/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toStringTag/shell.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toStringTag/shell.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-calendar-datefromfields-called-with-null-prototype-fields.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-calendar-datefromfields-called-with-null-prototype-fields.js
new file mode 100644
index 0000000000..7f77120445
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-calendar-datefromfields-called-with-null-prototype-fields.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: >
+    Calendar.dateFromFields method is called with a null-prototype fields object
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const calendar = TemporalHelpers.calendarCheckFieldsPrototypePollution();
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+const arg = { year: 2000, month: 5, day: 2, calendar };
+instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" });
+assert.sameValue(calendar.dateFromFieldsCallCount, 1, "dateFromFields should be called on the property bag's calendar");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-leap-second.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-leap-second.js
new file mode 100644
index 0000000000..31250ad462
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-leap-second.js
@@ -0,0 +1,29 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: Leap second is a valid ISO string for PlainDate
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+let arg = "2016-12-31T23:59:60";
+const result1 = instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" });
+assert.sameValue(
+  result1.epochNanoseconds,
+  1_483_187_696_987_654_321n,
+  "leap second is a valid ISO string for PlainDate"
+);
+
+arg = { year: 2016, month: 12, day: 31, hour: 23, minute: 59, second: 60 };
+const result2 = instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" });
+assert.sameValue(
+  result2.epochNanoseconds,
+  1_483_187_696_987_654_321n,
+  "second: 60 is ignored in property bag for PlainDate"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-number.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-number.js
new file mode 100644
index 0000000000..2c146f5937
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-number.js
@@ -0,0 +1,32 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: A number is converted to a string, then to Temporal.PlainDate
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const arg = 19761118;
+
+const result = instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" });
+assert.sameValue(result.epochNanoseconds, 217_168_496_987_654_321n, "19761118 is a valid ISO string for PlainDate");
+
+const numbers = [
+  1,
+  -19761118,
+  1234567890,
+];
+
+for (const arg of numbers) {
+  assert.throws(
+    RangeError,
+    () => instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" }),
+    `Number ${arg} does not convert to a valid ISO string for PlainDate`
+  );
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-plaindatetime.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-plaindatetime.js
new file mode 100644
index 0000000000..fd674c4701
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-plaindatetime.js
@@ -0,0 +1,32 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.tozoneddatetime
+description: Fast path for converting Temporal.PlainDateTime to Temporal.PlainDate by reading internal slots
+info: |
+    sec-temporal.plaintime.prototype.tozoneddatetime step 5:
+      5. Let _temporalDate_ be ? ToTemporalDate(_temporalDateLike_).
+    sec-temporal-totemporaldate step 2.b:
+      b. If _item_ has an [[InitializedTemporalDateTime]] internal slot, then
+        i. Return ! CreateTemporalDate(_item_.[[ISOYear]], _item_.[[ISOMonth]], _item_.[[ISODay]], _item_.[[Calendar]]).
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+TemporalHelpers.checkPlainDateTimeConversionFastPath((datetime) => {
+  const time = new Temporal.PlainTime(6, 54, 32, 123, 456, 789);
+  const result = time.toZonedDateTime({ plainDate: datetime, timeZone: "UTC" });
+  assert.sameValue(result.year, 2000, "year result");
+  assert.sameValue(result.month, 5, "month result");
+  assert.sameValue(result.day, 2, "day result");
+  assert.sameValue(result.hour, 6, "hour result");
+  assert.sameValue(result.minute, 54, "minute result");
+  assert.sameValue(result.second, 32, "second result");
+  assert.sameValue(result.millisecond, 123, "millisecond result");
+  assert.sameValue(result.microsecond, 456, "microsecond result");
+  assert.sameValue(result.nanosecond, 789, "nanosecond result");
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-primitive.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-primitive.js
new file mode 100644
index 0000000000..7b7b3cddc6
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-primitive.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.tozoneddatetime
+description: TypeError thrown if a primitive is passed as the argument
+info: |
+    Temporal.PlainTime.prototype.toZonedDateTime ( item )
+
+    3. If Type(item) is not Object, then
+        a. Throw a TypeError exception.
+features: [Symbol, Temporal]
+---*/
+
+const instance = Temporal.PlainTime.from("00:00");
+
+assert.throws(TypeError, () => instance.toZonedDateTime(undefined), "undefined");
+assert.throws(TypeError, () => instance.toZonedDateTime(null), "null");
+assert.throws(TypeError, () => instance.toZonedDateTime(true), "true");
+assert.throws(TypeError, () => instance.toZonedDateTime(""), "empty string");
+assert.throws(TypeError, () => instance.toZonedDateTime(Symbol()), "symbol");
+assert.throws(TypeError, () => instance.toZonedDateTime(1), "1");
+assert.throws(TypeError, () => instance.toZonedDateTime(1n), "1n");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-calendar-case-insensitive.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-calendar-case-insensitive.js
new file mode 100644
index 0000000000..6e8fac7cc7
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-calendar-case-insensitive.js
@@ -0,0 +1,23 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: The calendar name is case-insensitive
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const calendar = "IsO8601";
+
+let arg = { year: 1976, monthCode: "M11", day: 18, calendar };
+const result1 = instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" });
+assert.sameValue(result1.epochNanoseconds, 217_168_496_987_654_321n, "Calendar is case-insensitive");
+
+arg = { year: 1976, monthCode: "M11", day: 18, calendar: { calendar } };
+const result2 = instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" });
+assert.sameValue(result2.epochNanoseconds, 217_168_496_987_654_321n, "Calendar is case-insensitive (nested property)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-calendar-instance-does-not-get-calendar-property.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-calendar-instance-does-not-get-calendar-property.js
new file mode 100644
index 0000000000..d50d7698f1
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-calendar-instance-does-not-get-calendar-property.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: >
+  A Temporal.Calendar instance passed to toZonedDateTime() in a property bag does
+  not have its 'calendar' property observably checked
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const calendar = new Temporal.Calendar("iso8601");
+Object.defineProperty(calendar, "calendar", {
+  get() {
+    throw new Test262Error("calendar.calendar should not be accessed");
+  },
+});
+
+let arg = { year: 1976, monthCode: "M11", day: 18, calendar };
+instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" });
+
+arg = { year: 1976, monthCode: "M11", day: 18, calendar: { calendar } };
+instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" });
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-calendar-leap-second.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-calendar-leap-second.js
new file mode 100644
index 0000000000..3f667ad4bf
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-calendar-leap-second.js
@@ -0,0 +1,31 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: Leap second is a valid ISO string for a calendar in a property bag
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const calendar = "2016-12-31T23:59:60";
+
+let arg = { year: 1976, monthCode: "M11", day: 18, calendar };
+const result1 = instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" });
+assert.sameValue(
+  result1.epochNanoseconds,
+  217_168_496_987_654_321n,
+  "leap second is a valid ISO string for calendar"
+);
+
+arg = { year: 1976, monthCode: "M11", day: 18, calendar: { calendar } };
+const result2 = instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" });
+assert.sameValue(
+  result2.epochNanoseconds,
+  217_168_496_987_654_321n,
+  "leap second is a valid ISO string for calendar (nested property)"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-calendar-number.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-calendar-number.js
new file mode 100644
index 0000000000..d37d67a2a8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-calendar-number.js
@@ -0,0 +1,44 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: A number as calendar in a property bag is converted to a string, then to a calendar
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const calendar = 19970327;
+
+let arg = { year: 1976, monthCode: "M11", day: 18, calendar };
+const result1 = instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" });
+assert.sameValue(result1.epochNanoseconds, 217_168_496_987_654_321n, "19970327 is a valid ISO string for calendar");
+
+arg = { year: 1976, monthCode: "M11", day: 18, calendar: { calendar } };
+const result2 = instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" });
+assert.sameValue(result2.epochNanoseconds, 217_168_496_987_654_321n, "19970327 is a valid ISO string for calendar (nested property)");
+
+const numbers = [
+  1,
+  -19970327,
+  1234567890,
+];
+
+for (const calendar of numbers) {
+  let arg = { year: 1976, monthCode: "M11", day: 18, calendar };
+  assert.throws(
+    RangeError,
+    () => instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" }),
+    `Number ${calendar} does not convert to a valid ISO string for calendar`
+  );
+  arg = { year: 1976, monthCode: "M11", day: 18, calendar: { calendar } };
+  assert.throws(
+    RangeError,
+    () => instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" }),
+    `Number ${calendar} does not convert to a valid ISO string for calendar (nested property)`
+  );
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-calendar-string.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-calendar-string.js
new file mode 100644
index 0000000000..591bcc8a64
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-calendar-string.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: A calendar ID is valid input for Calendar
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const calendar = "iso8601";
+
+const arg = { year: 1976, monthCode: "M11", day: 18, calendar };
+const result = instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" });
+assert.sameValue(result.epochNanoseconds, 217_168_496_987_654_321n, `Calendar created from string "${calendar}"`);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-calendar-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-calendar-wrong-type.js
new file mode 100644
index 0000000000..d917b6029f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-calendar-wrong-type.js
@@ -0,0 +1,50 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: >
+  Appropriate error thrown when a calendar property from a property bag cannot
+  be converted to a calendar object or string
+features: [BigInt, Symbol, Temporal]
+---*/
+
+const timeZone = new Temporal.TimeZone("UTC");
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const rangeErrorTests = [
+  [null, "null"],
+  [true, "boolean"],
+  ["", "empty string"],
+  [1, "number that doesn't convert to a valid ISO string"],
+  [1n, "bigint"],
+];
+
+for (const [calendar, description] of rangeErrorTests) {
+  let arg = { year: 2019, monthCode: "M11", day: 1, calendar };
+  assert.throws(RangeError, () => instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" }), `${description} does not convert to a valid ISO string`);
+
+  arg = { year: 2019, monthCode: "M11", day: 1, calendar: { calendar } };
+  assert.throws(RangeError, () => instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" }), `${description} does not convert to a valid ISO string (nested property)`);
+}
+
+const typeErrorTests = [
+  [Symbol(), "symbol"],
+  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
+];
+
+for (const [calendar, description] of typeErrorTests) {
+  let arg = { year: 2019, monthCode: "M11", day: 1, calendar };
+  assert.throws(TypeError, () => instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" }), `${description} is not a valid property bag and does not convert to a string`);
+
+  arg = { year: 2019, monthCode: "M11", day: 1, calendar: { calendar } };
+  assert.throws(TypeError, () => instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" }), `${description} is not a valid property bag and does not convert to a string (nested property)`);
+}
+
+const arg = { year: 2019, monthCode: "M11", day: 1, calendar: { calendar: undefined } };
+assert.throws(RangeError, () => instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" }), `nested undefined calendar property is always a RangeError`);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-calendar-year-zero.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-calendar-year-zero.js
new file mode 100644
index 0000000000..30fa0c8745
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-calendar-year-zero.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: Negative zero, as an extended year, is rejected
+features: [Temporal, arrow-function]
+---*/
+
+const invalidStrings = [
+  "-000000-10-31",
+  "-000000-10-31T17:45",
+  "-000000-10-31T17:45Z",
+  "-000000-10-31T17:45+01:00",
+  "-000000-10-31T17:45+00:00[UTC]",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" }),
+    "reject minus zero as extended year"
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-missing-properties.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-missing-properties.js
new file mode 100644
index 0000000000..168b6103f1
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-missing-properties.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.tozoneddatetime
+description: Both plainDate and timeZone properties need to not be undefined.
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime();
+const plainDate = new Temporal.PlainDate(2022, 5, 19);
+const timeZone = new Temporal.TimeZone("UTC");
+assert.throws(TypeError, () => instance.toZonedDateTime({}),
+  "no properties");
+assert.throws(TypeError, () => instance.toZonedDateTime({ plainDate }),
+  "only plainDate");
+assert.throws(TypeError, () => instance.toZonedDateTime({ plainDate, timeZone: undefined }),
+  "timeZone explicitly undefined");
+assert.throws(TypeError, () => instance.toZonedDateTime({ timeZone }),
+  "only timeZone");
+assert.throws(TypeError, () => instance.toZonedDateTime({ plainDate: undefined, timeZone }),
+  "plainDate explicitly undefined");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-calendar-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-calendar-annotation.js
new file mode 100644
index 0000000000..db650aa5f5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-calendar-annotation.js
@@ -0,0 +1,34 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: Various forms of calendar annotation; critical flag has no effect
+features: [Temporal]
+---*/
+
+const tests = [
+  ["2000-05-02[u-ca=iso8601]", "without time or time zone"],
+  ["2000-05-02[UTC][u-ca=iso8601]", "with time zone and no time"],
+  ["2000-05-02T15:23[u-ca=iso8601]", "without time zone"],
+  ["2000-05-02T15:23[UTC][u-ca=iso8601]", "with time zone"],
+  ["2000-05-02T15:23[!u-ca=iso8601]", "with ! and no time zone"],
+  ["2000-05-02T15:23[UTC][!u-ca=iso8601]", "with ! and time zone"],
+  ["2000-05-02T15:23[u-ca=iso8601][u-ca=discord]", "second annotation ignored"],
+  ["2000-05-02T15:23[u-ca=iso8601][!u-ca=discord]", "second annotation ignored even with !"],
+];
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+tests.forEach(([arg, description]) => {
+  const result = instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" });
+
+  assert.sameValue(
+    result.epochNanoseconds,
+    957_270_896_987_654_321n,
+    `calendar annotation (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-critical-unknown-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-critical-unknown-annotation.js
new file mode 100644
index 0000000000..3750255f01
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-critical-unknown-annotation.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: Unknown annotations with critical flag are rejected
+features: [Temporal]
+---*/
+
+const invalidStrings = [
+  "1970-01-01[!foo=bar]",
+  "1970-01-01T00:00[!foo=bar]",
+  "1970-01-01T00:00[UTC][!foo=bar]",
+  "1970-01-01T00:00[u-ca=iso8601][!foo=bar]",
+  "1970-01-01T00:00[UTC][!foo=bar][u-ca=iso8601]",
+  "1970-01-01T00:00[foo=bar][!_foo-bar0=Dont-Ignore-This-99999999999]",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" }),
+    `reject unknown annotation with critical flag: ${arg}`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-date-with-utc-offset.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-date-with-utc-offset.js
new file mode 100644
index 0000000000..fc1fcff605
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-date-with-utc-offset.js
@@ -0,0 +1,48 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: UTC offset not valid with format that does not include a time
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const validStrings = [
+  "2000-05-02T00+00:00",
+  "2000-05-02T00+00:00[UTC]",
+  "2000-05-02T00+00:00[!UTC]",
+  "2000-05-02T00-02:30[America/St_Johns]",
+];
+
+for (const arg of validStrings) {
+  const result = instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" });
+
+  assert.sameValue(
+    result.epochNanoseconds,
+    957_270_896_987_654_321n,
+    `"${arg}" is a valid UTC offset with time for PlainDate`
+  );
+}
+
+const invalidStrings = [
+  "2022-09-15Z",
+  "2022-09-15Z[UTC]",
+  "2022-09-15Z[Europe/Vienna]",
+  "2022-09-15+00:00",
+  "2022-09-15+00:00[UTC]",
+  "2022-09-15-02:30",
+  "2022-09-15-02:30[America/St_Johns]",
+];
+
+for (const arg of invalidStrings) {
+  assert.throws(
+    RangeError,
+    () => instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" }),
+    `"${arg}" UTC offset without time is not valid for PlainDate`
+  );
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-invalid.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-invalid.js
new file mode 100644
index 0000000000..487fe68188
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-invalid.js
@@ -0,0 +1,64 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: >
+  RangeError thrown if an invalid ISO string (or syntactically valid ISO string
+  that is not supported) is used as a PlainDate
+features: [Temporal, arrow-function]
+---*/
+
+const invalidStrings = [
+  // invalid ISO strings:
+  "",
+  "invalid iso8601",
+  "2020-01-00",
+  "2020-01-32",
+  "2020-02-30",
+  "2021-02-29",
+  "2020-00-01",
+  "2020-13-01",
+  "2020-01-01T",
+  "2020-01-01T25:00:00",
+  "2020-01-01T01:60:00",
+  "2020-01-01T01:60:61",
+  "2020-01-01junk",
+  "2020-01-01T00:00:00junk",
+  "2020-01-01T00:00:00+00:00junk",
+  "2020-01-01T00:00:00+00:00[UTC]junk",
+  "2020-01-01T00:00:00+00:00[UTC][u-ca=iso8601]junk",
+  "02020-01-01",
+  "2020-001-01",
+  "2020-01-001",
+  "2020-01-01T001",
+  "2020-01-01T01:001",
+  "2020-01-01T01:01:001",
+  // valid, but forms not supported in Temporal:
+  "2020-W01-1",
+  "2020-001",
+  "+0002020-01-01",
+  // valid, but this calendar must not exist:
+  "2020-01-01[u-ca=notexist]",
+  // may be valid in other contexts, but insufficient information for PlainDate:
+  "2020-01",
+  "+002020-01",
+  "01-01",
+  "2020-W01",
+  "P1Y",
+  "-P12Y",
+  // valid, but outside the supported range:
+  "-999999-01-01",
+  "+999999-01-01",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+for (const arg of invalidStrings) {
+  assert.throws(
+    RangeError,
+    () => instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" }),
+    `"${arg}" should not be a valid ISO string for a PlainDate`
+  );
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-multiple-time-zone.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-multiple-time-zone.js
new file mode 100644
index 0000000000..529d0199ce
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-multiple-time-zone.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: More than one time zone annotation is not syntactical
+features: [Temporal]
+---*/
+
+const invalidStrings = [
+  "1970-01-01[UTC][UTC]",
+  "1970-01-01T00:00[UTC][UTC]",
+  "1970-01-01T00:00[!UTC][UTC]",
+  "1970-01-01T00:00[UTC][!UTC]",
+  "1970-01-01T00:00[UTC][u-ca=iso8601][UTC]",
+  "1970-01-01T00:00[UTC][foo=bar][UTC]",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" }),
+    `reject more than one time zone annotation: ${arg}`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-time-separators.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-time-separators.js
new file mode 100644
index 0000000000..3a35d9821e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-time-separators.js
@@ -0,0 +1,29 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: Time separator in string argument can vary
+features: [Temporal]
+---*/
+
+const tests = [
+  ["2000-05-02T15:23", "uppercase T"],
+  ["2000-05-02t15:23", "lowercase T"],
+  ["2000-05-02 15:23", "space between date and time"],
+];
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+tests.forEach(([arg, description]) => {
+  const result = instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" });
+
+  assert.sameValue(
+    result.epochNanoseconds,
+    957_270_896_987_654_321n,
+    `variant time separators (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-time-zone-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-time-zone-annotation.js
new file mode 100644
index 0000000000..594c7e64ab
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-time-zone-annotation.js
@@ -0,0 +1,38 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: Various forms of time zone annotation; critical flag has no effect
+features: [Temporal]
+---*/
+
+const tests = [
+  ["2000-05-02[Asia/Kolkata]", "named, with no time"],
+  ["2000-05-02[!Europe/Vienna]", "named, with ! and no time"],
+  ["2000-05-02[+00:00]", "numeric, with no time"],
+  ["2000-05-02[!-02:30]", "numeric, with ! and no time"],
+  ["2000-05-02T15:23[America/Sao_Paulo]", "named, with no offset"],
+  ["2000-05-02T15:23[!Asia/Tokyo]", "named, with ! and no offset"],
+  ["2000-05-02T15:23[-02:30]", "numeric, with no offset"],
+  ["2000-05-02T15:23[!+00:00]", "numeric, with ! and no offset"],
+  ["2000-05-02T15:23+00:00[America/New_York]", "named, with offset"],
+  ["2000-05-02T15:23+00:00[!UTC]", "named, with offset and !"],
+  ["2000-05-02T15:23+00:00[+01:00]", "numeric, with offset"],
+  ["2000-05-02T15:23+00:00[!-08:00]", "numeric, with offset and !"],
+];
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+tests.forEach(([arg, description]) => {
+  const result = instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" });
+
+  assert.sameValue(
+    result.epochNanoseconds,
+    957_270_896_987_654_321n,
+    `time zone annotation (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-unknown-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-unknown-annotation.js
new file mode 100644
index 0000000000..0a6f0b1648
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-unknown-annotation.js
@@ -0,0 +1,32 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: Various forms of unknown annotation
+features: [Temporal]
+---*/
+
+const tests = [
+  ["2000-05-02[foo=bar]", "without time"],
+  ["2000-05-02T15:23[foo=bar]", "alone"],
+  ["2000-05-02T15:23[UTC][foo=bar]", "with time zone"],
+  ["2000-05-02T15:23[u-ca=iso8601][foo=bar]", "with calendar"],
+  ["2000-05-02T15:23[UTC][foo=bar][u-ca=iso8601]", "with time zone and calendar"],
+  ["2000-05-02T15:23[foo=bar][_foo-bar0=Ignore-This-999999999999]", "with another unknown annotation"],
+];
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+tests.forEach(([arg, description]) => {
+  const result = instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" });
+
+  assert.sameValue(
+    result.epochNanoseconds,
+    957_270_896_987_654_321n,
+    `unknown annotation (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-with-utc-designator.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-with-utc-designator.js
new file mode 100644
index 0000000000..d49a144a5b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-string-with-utc-designator.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: RangeError thrown if a string with UTC designator is used as a PlainDate
+features: [Temporal, arrow-function]
+---*/
+
+const invalidStrings = [
+  "2019-10-01T09:00:00Z",
+  "2019-10-01T09:00:00Z[UTC]",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" }),
+    "String with UTC designator should not be valid as a PlainDate"
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-wrong-type.js
new file mode 100644
index 0000000000..6daa1a4e5f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-wrong-type.js
@@ -0,0 +1,39 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: >
+  Appropriate error thrown when argument cannot be converted to a valid string
+  or property bag for PlainDate
+features: [BigInt, Symbol, Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const rangeErrorTests = [
+  [null, "null"],
+  [true, "boolean"],
+  ["", "empty string"],
+  [1, "number that doesn't convert to a valid ISO string"],
+  [1n, "bigint"],
+];
+
+for (const [arg, description] of rangeErrorTests) {
+  assert.throws(RangeError, () => instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" }), `${description} does not convert to a valid ISO string`);
+}
+
+const typeErrorTests = [
+  [undefined, "undefined"],  // plainDate property is required
+  [Symbol(), "symbol"],
+  [{}, "plain object"],
+  [Temporal.PlainDate, "Temporal.PlainDate, object"],
+  [Temporal.PlainDate.prototype, "Temporal.PlainDate.prototype, object"],
+];
+
+for (const [arg, description] of typeErrorTests) {
+  assert.throws(TypeError, () => instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" }), `${description} is not a valid property bag and does not convert to a string`);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-zoneddatetime-convert.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-zoneddatetime-convert.js
new file mode 100644
index 0000000000..7b4c000b41
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-zoneddatetime-convert.js
@@ -0,0 +1,22 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: An exception from TimeZone#getOffsetNanosecondsFor() is propagated.
+features: [Temporal]
+---*/
+
+class TZ extends Temporal.TimeZone {
+  constructor() { super("UTC") }
+  getOffsetNanosecondsFor() { throw new Test262Error() }
+}
+
+const tz = new TZ();
+const arg = new Temporal.ZonedDateTime(0n, tz);
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+assert.throws(Test262Error, () => instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" }));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-zoneddatetime-slots.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-zoneddatetime-slots.js
new file mode 100644
index 0000000000..7ff4e9f079
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-zoneddatetime-slots.js
@@ -0,0 +1,40 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: Getters are not called when converting a ZonedDateTime to a PlainDate.
+includes: [compareArray.js]
+features: [Temporal]
+---*/
+
+const actual = [];
+const prototypeDescrs = Object.getOwnPropertyDescriptors(Temporal.ZonedDateTime.prototype);
+const getters = ["year", "month", "monthCode", "day", "hour", "minute", "second", "millisecond", "microsecond", "nanosecond", "calendar"];
+
+for (const property of getters) {
+  Object.defineProperty(Temporal.ZonedDateTime.prototype, property, {
+    get() {
+      actual.push(`get ${property}`);
+      const value = prototypeDescrs[property].get.call(this);
+      return {
+        toString() {
+          actual.push(`toString ${property}`);
+          return value.toString();
+        },
+        valueOf() {
+          actual.push(`valueOf ${property}`);
+          return value;
+        },
+      };
+    },
+  });
+}
+
+const arg = new Temporal.ZonedDateTime(0n, "UTC");
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" });
+assert.compareArray(actual, []);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-non-integer.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-non-integer.js
new file mode 100644
index 0000000000..79c1bf10be
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-non-integer.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: RangeError thrown if time zone reports an offset that is not an integer number of nanoseconds
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[3600_000_000_000.5, NaN, -Infinity, Infinity].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  assert.throws(RangeError, () => time.toZonedDateTime({ plainDate: datetime, timeZone: "UTC" }));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js
new file mode 100644
index 0000000000..e2bece3a1e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js
@@ -0,0 +1,23 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: TypeError thrown if timeZone.getOffsetNanosecondsFor is not callable
+features: [BigInt, Symbol, Temporal, arrow-function]
+---*/
+
+[undefined, null, true, Math.PI, 'string', Symbol('sym'), 42n, {}].forEach((notCallable) => {
+  const timeZone = new Temporal.TimeZone("UTC");
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  timeZone.getOffsetNanosecondsFor = notCallable;
+  assert.throws(
+    TypeError,
+    () => time.toZonedDateTime({ plainDate: datetime, timeZone: "UTC" }),
+    `Uncallable ${notCallable === null ? 'null' : typeof notCallable} getOffsetNanosecondsFor should throw TypeError`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-out-of-range.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-out-of-range.js
new file mode 100644
index 0000000000..cf5c4cbf07
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-out-of-range.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: RangeError thrown if time zone reports an offset that is out of range
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[-86400_000_000_000, 86400_000_000_000].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  assert.throws(RangeError, () => time.toZonedDateTime({ plainDate: datetime, timeZone: "UTC" }));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-wrong-type.js
new file mode 100644
index 0000000000..f1756d94b4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-wrong-type.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: TypeError thrown if time zone reports an offset that is not a Number
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[
+  undefined,
+  null,
+  true,
+  "+01:00",
+  Symbol(),
+  3600_000_000_000n,
+  {},
+  { valueOf() { return 3600_000_000_000; } },
+].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  assert.throws(TypeError, () => time.toZonedDateTime({ plainDate: datetime, timeZone: "UTC" }));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/basic.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/basic.js
new file mode 100644
index 0000000000..63c7b643b7
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/basic.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.tozoneddatetime
+description: Basic tests for toZonedDateTime().
+features: [Temporal]
+---*/
+
+const plainTime = Temporal.PlainTime.from('12:00');
+const plainDate = Temporal.PlainDate.from('2020-07-08');
+const timeZone = Temporal.TimeZone.from('-07:00');
+
+const objects = plainTime.toZonedDateTime({ timeZone, plainDate });
+assert.sameValue(objects.epochNanoseconds, 1594234800000000000n, "objects: epochNanoseconds");
+assert.sameValue(objects.timeZone, timeZone, "objects: timeZone");
+
+const timeZoneString = plainTime.toZonedDateTime({ timeZone: "-07:00", plainDate });
+assert.sameValue(timeZoneString.epochNanoseconds, 1594234800000000000n, "timeZone string: epochNanoseconds");
+assert.sameValue(timeZoneString.timeZone.id, "-07:00", "timeZone string: timeZone");
+
+const plainDateString = plainTime.toZonedDateTime({ timeZone, plainDate: "2020-07-08" });
+assert.sameValue(plainDateString.epochNanoseconds, 1594234800000000000n, "plainDate string: epochNanoseconds");
+assert.sameValue(plainDateString.timeZone.id, "-07:00", "plainDate string: timeZone");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/branding.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/branding.js
new file mode 100644
index 0000000000..c4b648b688
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/branding.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: Throw a TypeError if the receiver is invalid
+features: [Symbol, Temporal]
+---*/
+
+const toZonedDateTime = Temporal.PlainTime.prototype.toZonedDateTime;
+
+assert.sameValue(typeof toZonedDateTime, "function");
+
+const args = [{ plainDate: "2022-05-19", timeZone: "UTC" }];
+
+assert.throws(TypeError, () => toZonedDateTime.apply(undefined, args), "undefined");
+assert.throws(TypeError, () => toZonedDateTime.apply(null, args), "null");
+assert.throws(TypeError, () => toZonedDateTime.apply(true, args), "true");
+assert.throws(TypeError, () => toZonedDateTime.apply("", args), "empty string");
+assert.throws(TypeError, () => toZonedDateTime.apply(Symbol(), args), "symbol");
+assert.throws(TypeError, () => toZonedDateTime.apply(1, args), "1");
+assert.throws(TypeError, () => toZonedDateTime.apply({}, args), "plain object");
+assert.throws(TypeError, () => toZonedDateTime.apply(Temporal.PlainTime, args), "Temporal.PlainTime");
+assert.throws(TypeError, () => toZonedDateTime.apply(Temporal.PlainTime.prototype, args), "Temporal.PlainTime.prototype");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/builtin.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/builtin.js
new file mode 100644
index 0000000000..ea480e2433
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/builtin.js
@@ -0,0 +1,36 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: >
+    Tests that Temporal.PlainTime.prototype.toZonedDateTime
+    meets the requirements for built-in objects defined by the
+    introduction of chapter 17 of the ECMAScript Language Specification.
+info: |
+    Built-in functions that are not constructors do not have a "prototype" property unless
+    otherwise specified in the description of a particular function.
+
+    Unless specified otherwise, a built-in object that is callable as a function is a built-in
+    function object with the characteristics described in 10.3. Unless specified otherwise, the
+    [[Extensible]] internal slot of a built-in object initially has the value true.
+
+    Unless otherwise specified every built-in function and every built-in constructor has the
+    Function prototype object [...] as the value of its [[Prototype]] internal slot.
+features: [Temporal]
+---*/
+
+assert.sameValue(Object.isExtensible(Temporal.PlainTime.prototype.toZonedDateTime),
+  true, "Built-in objects must be extensible.");
+
+assert.sameValue(Object.prototype.toString.call(Temporal.PlainTime.prototype.toZonedDateTime),
+  "[object Function]", "Object.prototype.toString");
+
+assert.sameValue(Object.getPrototypeOf(Temporal.PlainTime.prototype.toZonedDateTime),
+  Function.prototype, "prototype");
+
+assert.sameValue(Temporal.PlainTime.prototype.toZonedDateTime.hasOwnProperty("prototype"),
+  false, "prototype property");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/calendar-dateadd-called-with-options-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/calendar-dateadd-called-with-options-undefined.js
new file mode 100644
index 0000000000..edcc4dc315
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/calendar-dateadd-called-with-options-undefined.js
@@ -0,0 +1,20 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: >
+    BuiltinTimeZoneGetInstantFor calls Calendar.dateAdd with undefined as the
+    options value
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const calendar = TemporalHelpers.calendarDateAddUndefinedOptions();
+const timeZone = TemporalHelpers.oneShiftTimeZone(new Temporal.Instant(0n), 3600e9);
+const instance = new Temporal.PlainTime();
+instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(1970, 1, 1, calendar), timeZone });
+assert.sameValue(calendar.dateAddCallCount, 1);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/calendar-datefromfields-called-with-options-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/calendar-datefromfields-called-with-options-undefined.js
new file mode 100644
index 0000000000..187323860d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/calendar-datefromfields-called-with-options-undefined.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: >
+    Calendar.dateFromFields method is called with undefined as the options value
+    when call originates internally
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const calendar = TemporalHelpers.calendarFromFieldsUndefinedOptions();
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321, calendar);
+instance.toZonedDateTime({ plainDate: { year: 2000, month: 5, day: 3, calendar }, timeZone: new Temporal.TimeZone("UTC") });
+assert.sameValue(calendar.dateFromFieldsCallCount, 1);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/calendar-fields-iterable.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/calendar-fields-iterable.js
new file mode 100644
index 0000000000..b96686f5db
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/calendar-fields-iterable.js
@@ -0,0 +1,34 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: Verify the result of calendar.fields() is treated correctly.
+info: |
+    sec-temporal.plaintime.prototype.tozoneddatetime step 5:
+      3. Let _temporalDate_ be ? ToTemporalDate(_temporalDateLike_).
+    sec-temporal-totemporaldate step 2.c:
+      c. Let _fieldNames_ be ? CalendarFields(_calendar_, « *"day"*, *"month"*, *"monthCode"*, *"year"* »).
+    sec-temporal-calendarfields step 4:
+      4. Let _result_ be ? IterableToList(_fieldsArray_).
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const expected = [
+  "day",
+  "month",
+  "monthCode",
+  "year",
+];
+
+const time = new Temporal.PlainTime(13, 3);
+const calendar = TemporalHelpers.calendarFieldsIterable();
+time.toZonedDateTime({ plainDate: { year: 2000, month: 5, day: 3, calendar }, timeZone: "UTC" });
+
+assert.sameValue(calendar.fieldsCallCount, 1, "fields() method called once");
+assert.compareArray(calendar.fieldsCalledWith[0], expected, "fields() method called with correct args");
+assert(calendar.iteratorExhausted[0], "iterated through the whole iterable");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/calendar-temporal-object.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/calendar-temporal-object.js
new file mode 100644
index 0000000000..1097b3f143
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/calendar-temporal-object.js
@@ -0,0 +1,30 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: Fast path for converting other Temporal objects to Temporal.Calendar by reading internal slots
+info: |
+    sec-temporal.plaintime.prototype.tozoneddatetime step 5:
+      5. Let _temporalDate_ be ? ToTemporalDate(_temporalDateLike_).
+    sec-temporal-totemporaldate step 2.c:
+      c. Let _calendar_ be ? GetTemporalCalendarWithISODefault(_item_).
+    sec-temporal-gettemporalcalendarwithisodefault step 2:
+      2. Return ? ToTemporalCalendarWithISODefault(_calendar_).
+    sec-temporal-totemporalcalendarwithisodefault step 2:
+      3. Return ? ToTemporalCalendar(_temporalCalendarLike_).
+    sec-temporal-totemporalcalendar step 1.a:
+      a. If _temporalCalendarLike_ has an [[InitializedTemporalDate]], [[InitializedTemporalDateTime]], [[InitializedTemporalMonthDay]], [[InitializedTemporalYearMonth]], or [[InitializedTemporalZonedDateTime]] internal slot, then
+        i. Return _temporalCalendarLike_.[[Calendar]].
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+TemporalHelpers.checkToTemporalCalendarFastPath((temporalObject, calendar) => {
+  const time = new Temporal.PlainTime(13, 3);
+  const result = time.toZonedDateTime({ timeZone: "UTC", plainDate: { year: 2000, month: 5, day: 3, calendar: temporalObject } });
+  assert.sameValue(result.calendar, calendar, "Temporal object coerced to calendar");
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/infinity-throws-rangeerror.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/infinity-throws-rangeerror.js
new file mode 100644
index 0000000000..e47eaaa99a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/infinity-throws-rangeerror.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Throws if any value in the property bag is Infinity or -Infinity
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(15);
+const base = { year: 2000, month: 5, day: 2 };
+
+[Infinity, -Infinity].forEach((inf) => {
+  ["year", "month", "day"].forEach((prop) => {
+    assert.throws(RangeError, () => instance.toZonedDateTime({ timeZone: "UTC", plainDate: { ...base, [prop]: inf } }), `${prop} property cannot be ${inf}`);
+
+    const calls = [];
+    const obj = TemporalHelpers.toPrimitiveObserver(calls, inf, prop);
+    assert.throws(RangeError, () => instance.toZonedDateTime({ timeZone: "UTC", plainDate: { ...base, [prop]: obj } }));
+    assert.compareArray(calls, [`get ${prop}.valueOf`, `call ${prop}.valueOf`], "it fails after fetching the primitive value");
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/length.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/length.js
new file mode 100644
index 0000000000..231e5cd877
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/length.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: Temporal.PlainTime.prototype.toZonedDateTime.length is 1
+info: |
+    Every built-in function object, including constructors, has a "length" property whose value is
+    an integer. Unless otherwise specified, this value is equal to the largest number of named
+    arguments shown in the subclause headings for the function description. Optional parameters
+    (which are indicated with brackets: [ ]) or rest parameters (which are shown using the form
+    «...name») are not included in the default argument count.
+
+    Unless otherwise specified, the "length" property of a built-in function object has the
+    attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.toZonedDateTime, "length", {
+  value: 1,
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/name.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/name.js
new file mode 100644
index 0000000000..ff102582d9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/name.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: Temporal.PlainTime.prototype.toZonedDateTime.name is "toZonedDateTime".
+info: |
+    Every built-in function object, including constructors, that is not identified as an anonymous
+    function has a "name" property whose value is a String. Unless otherwise specified, this value
+    is the name that is given to the function in this specification.
+
+    Unless otherwise specified, the "name" property of a built-in function object, if it exists,
+    has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.toZonedDateTime, "name", {
+  value: "toZonedDateTime",
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/not-a-constructor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/not-a-constructor.js
new file mode 100644
index 0000000000..2009c22baf
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/not-a-constructor.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: >
+  Temporal.PlainTime.prototype.toZonedDateTime does not implement [[Construct]], is not new-able
+info: |
+    Built-in function objects that are not identified as constructors do not implement the
+    [[Construct]] internal method unless otherwise specified in the description of a particular
+    function.
+includes: [isConstructor.js]
+features: [Reflect.construct, Temporal]
+---*/
+
+assert.throws(TypeError, () => {
+  new Temporal.PlainTime.prototype.toZonedDateTime();
+}, "Calling as constructor");
+
+assert.sameValue(isConstructor(Temporal.PlainTime.prototype.toZonedDateTime), false,
+  "isConstructor(Temporal.PlainTime.prototype.toZonedDateTime)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/plaindate-infinity-throws-rangeerror.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/plaindate-infinity-throws-rangeerror.js
new file mode 100644
index 0000000000..702bbfe6b5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/plaindate-infinity-throws-rangeerror.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Throws if any value in the property bag is Infinity or -Infinity
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(15);
+const base = { year: 2000, month: 5, day: 2 };
+
+[Infinity, -Infinity].forEach((inf) => {
+  ["year", "month", "day"].forEach((prop) => {
+    assert.throws(RangeError, () => instance.toZonedDateTime({ timeZone: "UTC", plainDate: { ...base, [prop]: inf } }), `${prop} property cannot be ${inf} in plainDate`);
+
+    const calls = [];
+    const obj = TemporalHelpers.toPrimitiveObserver(calls, inf, prop);
+    assert.throws(RangeError, () => instance.toZonedDateTime({ timeZone: "UTC", plainDate: { ...base, [prop]: obj } }));
+    assert.compareArray(calls, [`get ${prop}.valueOf`, `call ${prop}.valueOf`], "it fails after fetching the primitive value");
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/prop-desc.js
new file mode 100644
index 0000000000..d40ceb75dc
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/prop-desc.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: The "toZonedDateTime" property of Temporal.PlainTime.prototype
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+assert.sameValue(
+  typeof Temporal.PlainTime.prototype.toZonedDateTime,
+  "function",
+  "`typeof PlainTime.prototype.toZonedDateTime` is `function`"
+);
+
+verifyProperty(Temporal.PlainTime.prototype, "toZonedDateTime", {
+  writable: true,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-case-insensitive.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-case-insensitive.js
new file mode 100644
index 0000000000..e2fc4c4e72
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-case-insensitive.js
@@ -0,0 +1,17 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: Time zone names are case insensitive
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(); 
+
+const timeZone = 'uTc';
+const result = instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone });
+assert.sameValue(result.timeZone.id, 'UTC', `Time zone created from string "${timeZone}"`);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-getoffsetnanosecondsfor-non-integer.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-getoffsetnanosecondsfor-non-integer.js
new file mode 100644
index 0000000000..31070fcb67
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-getoffsetnanosecondsfor-non-integer.js
@@ -0,0 +1,22 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: RangeError thrown if time zone reports an offset that is not an integer number of nanoseconds
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[3600_000_000_000.5, NaN, -Infinity, Infinity].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const plainDate = new Temporal.PlainDate(2000, 5, 2);
+  timeZone.getPossibleInstantsFor = function () {
+    return [];
+  };
+  assert.throws(RangeError, () => time.toZonedDateTime({ plainDate, timeZone }));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-getoffsetnanosecondsfor-not-callable.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-getoffsetnanosecondsfor-not-callable.js
new file mode 100644
index 0000000000..c28178934f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-getoffsetnanosecondsfor-not-callable.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: TypeError thrown if timeZone.getOffsetNanosecondsFor is not callable
+features: [BigInt, Symbol, Temporal, arrow-function]
+---*/
+
+[undefined, null, true, Math.PI, 'string', Symbol('sym'), 42n, {}].forEach((notCallable) => {
+  const timeZone = new Temporal.TimeZone("UTC");
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const plainDate = new Temporal.PlainDate(2000, 5, 2);
+  timeZone.getPossibleInstantsFor = function () {
+    return [];
+  };
+  timeZone.getOffsetNanosecondsFor = notCallable;
+  assert.throws(
+    TypeError,
+    () => time.toZonedDateTime({ plainDate, timeZone }),
+    `Uncallable ${notCallable === null ? 'null' : typeof notCallable} getOffsetNanosecondsFor should throw TypeError`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-getoffsetnanosecondsfor-out-of-range.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-getoffsetnanosecondsfor-out-of-range.js
new file mode 100644
index 0000000000..cc99697449
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-getoffsetnanosecondsfor-out-of-range.js
@@ -0,0 +1,22 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: RangeError thrown if time zone reports an offset that is out of range
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[-86400_000_000_000, 86400_000_000_000].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const plainDate = new Temporal.PlainDate(2000, 5, 2);
+  timeZone.getPossibleInstantsFor = function () {
+    return [];
+  };
+  assert.throws(RangeError, () => time.toZonedDateTime({ plainDate, timeZone }));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-getoffsetnanosecondsfor-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-getoffsetnanosecondsfor-wrong-type.js
new file mode 100644
index 0000000000..3aa09919e9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-getoffsetnanosecondsfor-wrong-type.js
@@ -0,0 +1,31 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: TypeError thrown if time zone reports an offset that is not a Number
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[
+  undefined,
+  null,
+  true,
+  "+01:00",
+  Symbol(),
+  3600_000_000_000n,
+  {},
+  { valueOf() { return 3600_000_000_000; } },
+].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const plainDate = new Temporal.PlainDate(2000, 5, 2);
+  timeZone.getPossibleInstantsFor = function () {
+    return [];
+  };
+  assert.throws(TypeError, () => time.toZonedDateTime({ plainDate, timeZone }));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-getpossibleinstantsfor-iterable.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-getpossibleinstantsfor-iterable.js
new file mode 100644
index 0000000000..80ca4a77ad
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-getpossibleinstantsfor-iterable.js
@@ -0,0 +1,45 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: An iterable returned from timeZone.getPossibleInstantsFor is consumed after each call
+info: |
+    sec-temporal.plaintime.prototype.tozoneddatetime step 10:
+      10. Let _instant_ be ? BuiltinTimeZoneGetInstantFor(_timeZone_, _temporalDateTime_, *"compatible"*).
+    sec-temporal-builtintimezonegetinstantfor step 1:
+      1. Let _possibleInstants_ be ? GetPossibleInstantsFor(_timeZone_, _dateTime_).
+    sec-temporal-builtintimezonegetinstantfor step 14:
+      14. Assert: _disambiguation_ is *"compatible"* or *"later"*.
+    sec-temporal-builtintimezonegetinstantfor step 16:
+      16. Set _possibleInstants_ to ? GetPossibleInstantsFor(_timeZone_, _later_).
+    sec-temporal-getpossibleinstantsfor step 2:
+      2. Let _list_ be ? IterableToList(_possibleInstants_).
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const expected1 = [
+  "2000-05-02T12:34:56.987654321",
+];
+
+TemporalHelpers.checkTimeZonePossibleInstantsIterable((timeZone) => {
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  time.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone });
+}, expected1);
+
+// Same, but test the other path where the time doesn't exist and
+// GetPossibleInstantsFor is called again on a later time
+
+const expected2 = [
+  "2030-01-01T00:30:00",
+  "2030-01-01T01:30:00",
+];
+
+TemporalHelpers.checkTimeZonePossibleInstantsIterable((timeZone) => {
+  const time = new Temporal.PlainTime(0, 30);
+  time.toZonedDateTime({ plainDate: new Temporal.PlainDate(2030, 1, 1), timeZone });
+}, expected2);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-instance-does-not-get-timeZone-property.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-instance-does-not-get-timeZone-property.js
new file mode 100644
index 0000000000..f100fd461f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-instance-does-not-get-timeZone-property.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: >
+  A Temporal.TimeZone instance passed to toZonedDateTime() does not have its
+  'timeZone' property observably checked
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime();
+
+const timeZone = new Temporal.TimeZone("UTC");
+Object.defineProperty(timeZone, "timeZone", {
+  get() {
+    throw new Test262Error("timeZone.timeZone should not be accessed");
+  },
+});
+
+instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone });
+instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone: { timeZone } });
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-string-datetime.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-string-datetime.js
new file mode 100644
index 0000000000..640a77d5c3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-string-datetime.js
@@ -0,0 +1,47 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: Conversion of ISO date-time strings to Temporal.TimeZone instances
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime();
+
+let timeZone = "2021-08-19T17:30";
+assert.throws(RangeError, () => instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone }), "bare date-time string is not a time zone");
+assert.throws(RangeError, () => instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone: { timeZone } }), "bare date-time string is not a time zone");
+
+timeZone = "2021-08-19T17:30Z";
+const result1 = instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone });
+assert.sameValue(result1.timeZone.id, "UTC", "date-time + Z is UTC time zone");
+const result2 = instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone: { timeZone } });
+assert.sameValue(result2.timeZone.id, "UTC", "date-time + Z is UTC time zone (string in property bag)");
+
+timeZone = "2021-08-19T17:30-07:00";
+const result3 = instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone });
+assert.sameValue(result3.timeZone.id, "-07:00", "date-time + offset is the offset time zone");
+const result4 = instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone: { timeZone } });
+assert.sameValue(result4.timeZone.id, "-07:00", "date-time + offset is the offset time zone (string in property bag)");
+
+timeZone = "2021-08-19T17:30[UTC]";
+const result5 = instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone });
+assert.sameValue(result5.timeZone.id, "UTC", "date-time + IANA annotation is the IANA time zone");
+const result6 = instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone: { timeZone } });
+assert.sameValue(result6.timeZone.id, "UTC", "date-time + IANA annotation is the IANA time zone (string in property bag)");
+
+timeZone = "2021-08-19T17:30Z[UTC]";
+const result7 = instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone });
+assert.sameValue(result7.timeZone.id, "UTC", "date-time + Z + IANA annotation is the IANA time zone");
+const result8 = instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone: { timeZone } });
+assert.sameValue(result8.timeZone.id, "UTC", "date-time + Z + IANA annotation is the IANA time zone (string in property bag)");
+
+timeZone = "2021-08-19T17:30-07:00[UTC]";
+const result9 = instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone });
+assert.sameValue(result9.timeZone.id, "UTC", "date-time + offset + IANA annotation is the IANA time zone");
+const result10 = instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone: { timeZone } });
+assert.sameValue(result10.timeZone.id, "UTC", "date-time + offset + IANA annotation is the IANA time zone (string in property bag)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-string-leap-second.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-string-leap-second.js
new file mode 100644
index 0000000000..809a1bc07d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-string-leap-second.js
@@ -0,0 +1,23 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: Leap second is a valid ISO string for TimeZone
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime();
+let timeZone = "2016-12-31T23:59:60+00:00[UTC]";
+
+const result1 = instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone });
+assert.sameValue(result1.timeZone.id, "UTC", "leap second is a valid ISO string for TimeZone");
+const result2 = instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone: { timeZone } });
+assert.sameValue(result2.timeZone.id, "UTC", "leap second is a valid ISO string for TimeZone (nested property)");
+
+timeZone = "2021-08-19T17:30:45.123456789+23:59[+23:59:60]";
+assert.throws(RangeError, () => instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone }), "leap second in time zone name not valid");
+assert.throws(RangeError, () => instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone: { timeZone } }), "leap second in time zone name not valid (nested property)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-string-multiple-offsets.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-string-multiple-offsets.js
new file mode 100644
index 0000000000..d3fe3666e3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-string-multiple-offsets.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: Time zone strings with UTC offset fractional part are not confused with time fractional part
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime();
+const timeZone = "2021-08-19T17:30:45.123456789+01:46[+01:45:30.987654321]";
+
+const result1 = instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone });
+assert.sameValue(result1.timeZone.id, "+01:45:30.987654321", "Time zone string determined from bracket name");
+const result2 = instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone: { timeZone } });
+assert.sameValue(result2.timeZone.id, "+01:45:30.987654321", "Time zone string determined from bracket name");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-string-year-zero.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-string-year-zero.js
new file mode 100644
index 0000000000..065d21083f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-string-year-zero.js
@@ -0,0 +1,29 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: Negative zero, as an extended year, is rejected
+features: [Temporal, arrow-function]
+---*/
+
+const invalidStrings = [
+  "-000000-10-31T17:45Z",
+  "-000000-10-31T17:45+00:00[UTC]",
+];
+const instance = new Temporal.PlainTime();
+invalidStrings.forEach((timeZone) => {
+  assert.throws(
+    RangeError,
+    () => instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone }),
+    "reject minus zero as extended year"
+  );
+  assert.throws(
+    RangeError,
+    () => instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone: { timeZone } }),
+    "reject minus zero as extended year (nested property)"
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-string.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-string.js
new file mode 100644
index 0000000000..3a783ad254
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-string.js
@@ -0,0 +1,18 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: Time zone IDs are valid input for a time zone
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime();
+
+["UTC", "+01:30"].forEach((timeZone) => {
+  const result = instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone });
+  assert.sameValue(result.timeZone.id, timeZone, `Time zone created from string "${timeZone}"`);
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-wrong-type.js
new file mode 100644
index 0000000000..0f6f5250df
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/timezone-wrong-type.js
@@ -0,0 +1,42 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: >
+  Appropriate error thrown when argument cannot be converted to a valid string
+  or object for TimeZone
+features: [BigInt, Symbol, Temporal]
+---*/
+
+const instance = new Temporal.PlainTime();
+
+const rangeErrorTests = [
+  [null, "null"],
+  [true, "boolean"],
+  ["", "empty string"],
+  [1, "number that doesn't convert to a valid ISO string"],
+  [19761118, "number that would convert to a valid ISO string in other contexts"],
+  [1n, "bigint"],
+  [new Temporal.Calendar("iso8601"), "calendar instance"],
+];
+
+for (const [timeZone, description] of rangeErrorTests) {
+  assert.throws(RangeError, () => instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone }), `${description} does not convert to a valid ISO string`);
+  assert.throws(RangeError, () => instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone: { timeZone } }), `${description} does not convert to a valid ISO string (nested property)`);
+}
+
+const typeErrorTests = [
+  [Symbol(), "symbol"],
+];
+
+for (const [timeZone, description] of typeErrorTests) {
+  assert.throws(TypeError, () => instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone }), `${description} is not a valid object and does not convert to a string`);
+  assert.throws(TypeError, () => instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone: { timeZone } }), `${description} is not a valid object and does not convert to a string (nested property)`);
+}
+
+const timeZone = undefined;
+assert.throws(RangeError, () => instance.toZonedDateTime({ plainDate: new Temporal.PlainDate(2000, 5, 2), timeZone: { timeZone } }), `undefined is always a RangeError as nested property`);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/year-zero.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/year-zero.js
new file mode 100644
index 0000000000..397cbf1d87
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/toZonedDateTime/year-zero.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.tozoneddatetime
+description: Negative zero, as an extended year, is rejected
+features: [Temporal, arrow-function]
+---*/
+
+const invalidStrings = [
+  "-000000-10-31",
+  "-000000-10-31T00:45",
+  "-000000-10-31T00:45+01:00",
+  "-000000-10-31T00:45+00:00[UTC]",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => instance.toZonedDateTime({ plainDate: arg, timeZone: "UTC" }),
+    "reject minus zero as extended year"
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-cast.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-cast.js
new file mode 100644
index 0000000000..4e386255e0
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-cast.js
@@ -0,0 +1,21 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Casts the argument
+includes: [temporalHelpers.js]
+features: [Temporal, arrow-function]
+---*/
+
+const plainTime = new Temporal.PlainTime(15, 23, 30, 123, 456, 789);
+TemporalHelpers.assertDuration(plainTime.until("16:34"),
+  0, 0, 0, 0, /* hours = */ 1, /* minutes = */ 10, /* seconds = */ 29, 876, 543, 211, "string");
+TemporalHelpers.assertDuration(plainTime.until({ hour: 16, minute: 34 }),
+  0, 0, 0, 0, /* hours = */ 1, /* minutes = */ 10, /* seconds = */ 29, 876, 543, 211, "object");
+
+assert.throws(TypeError, () => plainTime.until({}), "empty");
+assert.throws(TypeError, () => plainTime.until({ minutes: 30 }), "only plural 'minutes'");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-number.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-number.js
new file mode 100644
index 0000000000..5d0a25c19d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-number.js
@@ -0,0 +1,34 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: A number is converted to a string, then to Temporal.PlainTime
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const arg = 123456.987654321;
+
+const result = instance.until(arg);
+TemporalHelpers.assertDuration(result, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, "123456.987654321 is a valid ISO string for PlainTime");
+
+const numbers = [
+  1,
+  -123456.987654321,
+  1234567,
+  123456.9876543219,
+];
+
+for (const arg of numbers) {
+  assert.throws(
+    RangeError,
+    () => instance.until(arg),
+    `Number ${arg} does not convert to a valid ISO string for PlainTime`
+  );
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-calendar-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-calendar-annotation.js
new file mode 100644
index 0000000000..da82144a1f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-calendar-annotation.js
@@ -0,0 +1,41 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Various forms of calendar annotation; critical flag has no effect
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const tests = [
+  ["12:34:56.987654321[u-ca=iso8601]", "without time zone"],
+  ["12:34:56.987654321[UTC][u-ca=iso8601]", "with time zone"],
+  ["12:34:56.987654321[!u-ca=iso8601]", "with ! and no time zone"],
+  ["12:34:56.987654321[UTC][!u-ca=iso8601]", "with ! and time zone"],
+  ["T12:34:56.987654321[u-ca=iso8601]", "with T and no time zone"],
+  ["T12:34:56.987654321[UTC][u-ca=iso8601]", "with T and time zone"],
+  ["T12:34:56.987654321[!u-ca=iso8601]", "with T, !, and no time zone"],
+  ["T12:34:56.987654321[UTC][!u-ca=iso8601]", "with T, !, and time zone"],
+  ["1970-01-01T12:34:56.987654321[u-ca=iso8601]", "with date and no time zone"],
+  ["1970-01-01T12:34:56.987654321[UTC][u-ca=iso8601]", "with date and time zone"],
+  ["1970-01-01T12:34:56.987654321[!u-ca=iso8601]", "with !, date, and no time zone"],
+  ["1970-01-01T12:34:56.987654321[UTC][!u-ca=iso8601]", "with !, date, and time zone"],
+  ["1970-01-01T12:34:56.987654321[u-ca=iso8601][u-ca=discord]", "second annotation ignored"],
+  ["1970-01-01T12:34:56.987654321[u-ca=iso8601][!u-ca=discord]", "second annotation ignored even with !"],
+];
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+tests.forEach(([arg, description]) => {
+  const result = instance.until(arg);
+
+  TemporalHelpers.assertDuration(
+    result,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    `calendar annotation (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-critical-unknown-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-critical-unknown-annotation.js
new file mode 100644
index 0000000000..ea8ffb3e19
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-critical-unknown-annotation.js
@@ -0,0 +1,29 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Unknown annotations with critical flag are rejected
+features: [Temporal]
+---*/
+
+const invalidStrings = [
+  "00:00[!foo=bar]",
+  "T00:00[!foo=bar]",
+  "1970-01-01T00:00[!foo=bar]",
+  "1970-01-01T00:00[UTC][!foo=bar]",
+  "1970-01-01T00:00[u-ca=iso8601][!foo=bar]",
+  "1970-01-01T00:00[UTC][!foo=bar][u-ca=iso8601]",
+  "1970-01-01T00:00[foo=bar][!_foo-bar0=Dont-Ignore-This-99999999999]",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => instance.until(arg),
+    `reject unknown annotation with critical flag: ${arg}`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-date-with-utc-offset.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-date-with-utc-offset.js
new file mode 100644
index 0000000000..1664a5409e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-date-with-utc-offset.js
@@ -0,0 +1,53 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: UTC offset not valid with format that does not include a time
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const validStrings = [
+  "12:34:56.987654321+00:00",
+  "12:34:56.987654321+00:00[UTC]",
+  "12:34:56.987654321+00:00[!UTC]",
+  "12:34:56.987654321-02:30[America/St_Johns]",
+  "1976-11-18T12:34:56.987654321+00:00",
+  "1976-11-18T12:34:56.987654321+00:00[UTC]",
+  "1976-11-18T12:34:56.987654321+00:00[!UTC]",
+  "1976-11-18T12:34:56.987654321-02:30[America/St_Johns]",
+];
+
+for (const arg of validStrings) {
+  const result = instance.until(arg);
+
+  TemporalHelpers.assertDuration(
+    result,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    `"${arg}" is a valid UTC offset with time for PlainTime`
+  );
+}
+
+const invalidStrings = [
+  "2022-09-15Z",
+  "2022-09-15Z[UTC]",
+  "2022-09-15Z[Europe/Vienna]",
+  "2022-09-15+00:00",
+  "2022-09-15+00:00[UTC]",
+  "2022-09-15-02:30",
+  "2022-09-15-02:30[America/St_Johns]",
+];
+
+for (const arg of invalidStrings) {
+  assert.throws(
+    RangeError,
+    () => instance.until(arg),
+    `"${arg}" UTC offset without time is not valid for PlainTime`
+  );
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-multiple-time-zone.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-multiple-time-zone.js
new file mode 100644
index 0000000000..12d298ee1f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-multiple-time-zone.js
@@ -0,0 +1,29 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: More than one time zone annotation is not syntactical
+features: [Temporal]
+---*/
+
+const invalidStrings = [
+  "00:00[UTC][UTC]",
+  "T00:00[UTC][UTC]",
+  "1970-01-01T00:00[UTC][UTC]",
+  "1970-01-01T00:00[!UTC][UTC]",
+  "1970-01-01T00:00[UTC][!UTC]",
+  "1970-01-01T00:00[UTC][u-ca=iso8601][UTC]",
+  "1970-01-01T00:00[UTC][foo=bar][UTC]",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => instance.until(arg),
+    `reject more than one time zone annotation: ${arg}`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-no-implicit-midnight.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-no-implicit-midnight.js
new file mode 100644
index 0000000000..62217c639c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-no-implicit-midnight.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: RangeError thrown if a date-only string is passed in a PlainTime context
+features: [Temporal, arrow-function]
+---*/
+
+const arg = "2019-10-01";
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+assert.throws(
+  RangeError,
+  () => instance.until(arg),
+  "Date-only string throws, does not implicitly convert to midnight"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-time-designator-required-for-disambiguation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-time-designator-required-for-disambiguation.js
new file mode 100644
index 0000000000..13ab1e3517
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-time-designator-required-for-disambiguation.js
@@ -0,0 +1,37 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: ISO 8601 time designator "T" required in cases of ambiguity
+includes: [temporalHelpers.js]
+features: [Temporal, arrow-function]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+TemporalHelpers.ISO.plainTimeStringsAmbiguous().forEach((string) => {
+  let arg = string;
+  assert.throws(
+    RangeError,
+    () => instance.until(arg),
+    `'${arg}' is ambiguous and requires T prefix`
+  );
+  // The same string with a T prefix should not throw:
+  arg = `T${string}`;
+  instance.until(arg);
+
+  arg = ` ${string}`;
+  assert.throws(
+    RangeError,
+    () => instance.until(arg),
+    `space is not accepted as a substitute for T prefix: '${arg}'`
+  );
+});
+
+// None of these should throw without a T prefix, because they are unambiguously time strings:
+TemporalHelpers.ISO.plainTimeStringsUnambiguous().forEach(
+  (arg) => instance.until(arg));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-time-separators.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-time-separators.js
new file mode 100644
index 0000000000..53b614b013
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-time-separators.js
@@ -0,0 +1,32 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Time separator in string argument can vary
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const tests = [
+  ["1976-11-18T12:34:56.987654321", "uppercase T"],
+  ["1976-11-18t12:34:56.987654321", "lowercase T"],
+  ["1976-11-18 12:34:56.987654321", "space between date and time"],
+  ["T12:34:56.987654321", "time-only uppercase T"],
+  ["t12:34:56.987654321", "time-only lowercase T"],
+];
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+tests.forEach(([arg, description]) => {
+  const result = instance.until(arg);
+
+  TemporalHelpers.assertDuration(
+    result,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    `variant time separators (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-time-zone-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-time-zone-annotation.js
new file mode 100644
index 0000000000..e2e0152172
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-time-zone-annotation.js
@@ -0,0 +1,51 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Various forms of time zone annotation; critical flag has no effect
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const tests = [
+  ["12:34:56.987654321[Asia/Kolkata]", "named, with no offset"],
+  ["12:34:56.987654321[!Europe/Vienna]", "named, with ! and no offset"],
+  ["12:34:56.987654321[+00:00]", "numeric, with no offset"],
+  ["12:34:56.987654321[!-02:30]", "numeric, with ! and no offset"],
+  ["T12:34:56.987654321[UTC]", "named, with T and no offset"],
+  ["T12:34:56.987654321[!Africa/Abidjan]", "named, with T, !, and no offset"],
+  ["T12:34:56.987654321[+01:00]", "numeric, with T and no offset"],
+  ["T12:34:56.987654321[!-08:00]", "numeric, with T, !, and no offset"],
+  ["12:34:56.987654321+00:00[America/Sao_Paulo]", "named, with offset"],
+  ["12:34:56.987654321+00:00[!Asia/Tokyo]", "named, with ! and offset"],
+  ["12:34:56.987654321+00:00[-02:30]", "numeric, with offset"],
+  ["12:34:56.987654321+00:00[!+00:00]", "numeric, with ! and offset"],
+  ["T12:34:56.987654321+00:00[America/New_York]", "named, with T and offset"],
+  ["T12:34:56.987654321+00:00[!UTC]", "named, with T, !, and offset"],
+  ["T12:34:56.987654321+00:00[-08:00]", "numeric, with T and offset"],
+  ["T12:34:56.987654321+00:00[!+01:00]", "numeric, with T, !, and offset"],
+  ["1970-01-01T12:34:56.987654321[Africa/Lagos]", "named, with date and no offset"],
+  ["1970-01-01T12:34:56.987654321[!America/Vancouver]", "named, with date, !, and no offset"],
+  ["1970-01-01T12:34:56.987654321[+00:00]", "numeric, with date and no offset"],
+  ["1970-01-01T12:34:56.987654321[!-02:30]", "numeric, with date, !, and no offset"],
+  ["1970-01-01T12:34:56.987654321+00:00[Europe/London]", "named, with date and offset"],
+  ["1970-01-01T12:34:56.987654321+00:00[!Asia/Seoul]", "named, with date, offset, and !"],
+  ["1970-01-01T12:34:56.987654321+00:00[+01:00]", "numeric, with date and offset"],
+  ["1970-01-01T12:34:56.987654321+00:00[!-08:00]", "numeric, with date, offset, and !"],
+];
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+tests.forEach(([arg, description]) => {
+  const result = instance.until(arg);
+
+  TemporalHelpers.assertDuration(
+    result,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    `time zone annotation (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-unknown-annotation.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-unknown-annotation.js
new file mode 100644
index 0000000000..000b6eb455
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-unknown-annotation.js
@@ -0,0 +1,40 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Various forms of unknown annotation
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const tests = [
+  ["12:34:56.987654321[foo=bar]", "alone"],
+  ["12:34:56.987654321[UTC][foo=bar]", "with time zone"],
+  ["12:34:56.987654321[u-ca=iso8601][foo=bar]", "with calendar"],
+  ["12:34:56.987654321[UTC][foo=bar][u-ca=iso8601]", "with time zone and calendar"],
+  ["T12:34:56.987654321[foo=bar]", "with T"],
+  ["T12:34:56.987654321[UTC][foo=bar]", "with T and time zone"],
+  ["T12:34:56.987654321[u-ca=iso8601][foo=bar]", "with T and calendar"],
+  ["T12:34:56.987654321[UTC][foo=bar][u-ca=iso8601]", "with T, time zone, and calendar"],
+  ["1970-01-01T12:34:56.987654321[foo=bar]", "with date"],
+  ["1970-01-01T12:34:56.987654321[UTC][foo=bar]", "with date and time zone"],
+  ["1970-01-01T12:34:56.987654321[u-ca=iso8601][foo=bar]", "with date and calendar"],
+  ["1970-01-01T12:34:56.987654321[UTC][foo=bar][u-ca=iso8601]", "with date, time zone, and calendar"],
+  ["1970-01-01T12:34:56.987654321[foo=bar][_foo-bar0=Ignore-This-999999999999]", "with another unknown annotation"],
+];
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+tests.forEach(([arg, description]) => {
+  const result = instance.until(arg);
+
+  TemporalHelpers.assertDuration(
+    result,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    `unknown annotation (${description})`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-with-time-designator.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-with-time-designator.js
new file mode 100644
index 0000000000..9e45d7400c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-with-time-designator.js
@@ -0,0 +1,32 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: ISO 8601 time designator "T" allowed at the start of PlainTime strings
+includes: [temporalHelpers.js]
+features: [Temporal, arrow-function]
+---*/
+
+const instance = new Temporal.PlainTime(1, 0, 0, 0, 0, 1);
+const validStrings = [
+  "T00:30",
+  "t00:30",
+  "T0030",
+  "t0030",
+  "T00:30:00",
+  "t00:30:00",
+  "T003000",
+  "t003000",
+  "T00:30:00.000000000",
+  "t00:30:00.000000000",
+  "T003000.000000000",
+  "t003000.000000000",
+];
+validStrings.forEach((arg) => {
+  const result = instance.until(arg);
+  TemporalHelpers.assertDuration(result, 0, 0, 0, 0, 0, -30, 0, 0, 0, -1, `T prefix is accepted: ${arg}`);
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-with-utc-designator.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-with-utc-designator.js
new file mode 100644
index 0000000000..7fde7180ab
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-string-with-utc-designator.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: RangeError thrown if a string with UTC designator is used as a PlainTime
+features: [Temporal, arrow-function]
+---*/
+
+const invalidStrings = [
+  "2019-10-01T09:00:00Z",
+  "2019-10-01T09:00:00Z[UTC]",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => instance.until(arg),
+    "String with UTC designator should not be valid as a PlainTime"
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-wrong-type.js
new file mode 100644
index 0000000000..c86fa664c7
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-wrong-type.js
@@ -0,0 +1,39 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: >
+  Appropriate error thrown when argument cannot be converted to a valid string
+  or property bag for PlainTime
+features: [BigInt, Symbol, Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const rangeErrorTests = [
+  [undefined, "undefined"],
+  [null, "null"],
+  [true, "boolean"],
+  ["", "empty string"],
+  [1, "number that doesn't convert to a valid ISO string"],
+  [1n, "bigint"],
+];
+
+for (const [arg, description] of rangeErrorTests) {
+  assert.throws(RangeError, () => instance.until(arg), `${description} does not convert to a valid ISO string`);
+}
+
+const typeErrorTests = [
+  [Symbol(), "symbol"],
+  [{}, "plain object"],
+  [Temporal.PlainTime, "Temporal.PlainTime, object"],
+  [Temporal.PlainTime.prototype, "Temporal.PlainTime.prototype, object"],
+];
+
+for (const [arg, description] of typeErrorTests) {
+  assert.throws(TypeError, () => instance.until(arg), `${description} is not a valid property bag and does not convert to a string`);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-zoneddatetime-balance-negative-time-units.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-zoneddatetime-balance-negative-time-units.js
new file mode 100644
index 0000000000..0970d70a7e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-zoneddatetime-balance-negative-time-units.js
@@ -0,0 +1,46 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Negative time fields are balanced upwards if the argument is given as ZonedDateTime
+info: |
+    sec-temporal-balancetime steps 3–14:
+      3. Set _microsecond_ to _microsecond_ + floor(_nanosecond_ / 1000).
+      4. Set _nanosecond_ to _nanosecond_ modulo 1000.
+      5. Set _millisecond_ to _millisecond_ + floor(_microsecond_ / 1000).
+      6. Set _microsecond_ to _microsecond_ modulo 1000.
+      7. Set _second_ to _second_ + floor(_millisecond_ / 1000).
+      8. Set _millisecond_ to _millisecond_ modulo 1000.
+      9. Set _minute_ to _minute_ + floor(_second_ / 60).
+      10. Set _second_ to _second_ modulo 60.
+      11. Set _hour_ to _hour_ + floor(_minute_ / 60).
+      12. Set _minute_ to _minute_ modulo 60.
+      13. Let _days_ be floor(_hour_ / 24).
+      14. Set _hour_ to _hour_ modulo 24.
+    sec-temporal-balanceisodatetime step 1:
+      1. Let _balancedTime_ be ? BalanceTime(_hour_, _minute_, _second_, _millisecond_, _microsecond_, _nanosecond_).
+    sec-temporal-builtintimezonegetplaindatetimefor step 3:
+      3. Set _result_ to ? BalanceISODateTime(_result_.[[Year]], _result_.[[Month]], _result_.[[Day]], _result_.[[Hour]], _result_.[[Minute]], _result_.[[Second]], _result_.[[Millisecond]], _result_.[[Microsecond]], _result_.[[Nanosecond]] + _offsetNanoseconds_).
+    sec-temporal-totemporaltime step 3.b:
+      b. If _item_ has an [[InitializedTemporalZonedDateTime]] internal slot, then
+        ...
+        ii. 1. Set _plainDateTime_ to ? BuiltinTimeZoneGetPlainDateTimeFor(_item_.[[TimeZone]], _instant_, _item_.[[Calendar]]).
+    sec-temporal.plaintime.prototype.until step 3:
+      3. Set _other_ to ? ToTemporalTime(_other_).
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+// This code path is encountered if the time zone offset is negative and its
+// absolute value in nanoseconds is greater than the nanosecond field of the
+// exact time's epoch parts
+const tz = new Temporal.TimeZone("-00:00:00.000000002");
+const datetime = new Temporal.ZonedDateTime(3661_001_001_001n, tz);
+
+const diff = new Temporal.PlainTime().until(datetime);
+
+TemporalHelpers.assertDuration(diff, 0, 0, 0, 0, 1, 1, 1, 1, 0, 999);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-zoneddatetime-negative-epochnanoseconds.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-zoneddatetime-negative-epochnanoseconds.js
new file mode 100644
index 0000000000..870c32353e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-zoneddatetime-negative-epochnanoseconds.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: A pre-epoch value is handled correctly by the modulo operation in GetISOPartsFromEpoch
+info: |
+    sec-temporal-getisopartsfromepoch step 1:
+      1. Let _remainderNs_ be the mathematical value whose sign is the sign of _epochNanoseconds_ and whose magnitude is abs(_epochNanoseconds_) modulo 10<sup>6</sup>.
+    sec-temporal-builtintimezonegetplaindatetimefor step 2:
+      2. Let _result_ be ! GetISOPartsFromEpoch(_instant_.[[Nanoseconds]]).
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+const datetime = new Temporal.ZonedDateTime(-13849764_999_999_999n, "UTC");
+
+// This code path shows up anywhere we convert an exact time, before the Unix
+// epoch, with nonzero microseconds or nanoseconds, into a wall time.
+
+const instance = new Temporal.PlainTime(15);
+const result = instance.until(datetime);
+TemporalHelpers.assertDuration(result, 0, 0, 0, 0, 1, 50, 35, 0, 0, 1);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-non-integer.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-non-integer.js
new file mode 100644
index 0000000000..6ddbff9658
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-non-integer.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: RangeError thrown if time zone reports an offset that is not an integer number of nanoseconds
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[3600_000_000_000.5, NaN, -Infinity, Infinity].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  assert.throws(RangeError, () => time.until(datetime));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js
new file mode 100644
index 0000000000..9ff9542c40
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js
@@ -0,0 +1,23 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: TypeError thrown if timeZone.getOffsetNanosecondsFor is not callable
+features: [BigInt, Symbol, Temporal, arrow-function]
+---*/
+
+[undefined, null, true, Math.PI, 'string', Symbol('sym'), 42n, {}].forEach((notCallable) => {
+  const timeZone = new Temporal.TimeZone("UTC");
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  timeZone.getOffsetNanosecondsFor = notCallable;
+  assert.throws(
+    TypeError,
+    () => time.until(datetime),
+    `Uncallable ${notCallable === null ? 'null' : typeof notCallable} getOffsetNanosecondsFor should throw TypeError`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-out-of-range.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-out-of-range.js
new file mode 100644
index 0000000000..2159dd1cf9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-out-of-range.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: RangeError thrown if time zone reports an offset that is out of range
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[-86400_000_000_000, 86400_000_000_000].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  assert.throws(RangeError, () => time.until(datetime));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-wrong-type.js
new file mode 100644
index 0000000000..b86fba5de5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-wrong-type.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: TypeError thrown if time zone reports an offset that is not a Number
+features: [Temporal]
+includes: [temporalHelpers.js]
+---*/
+
+[
+  undefined,
+  null,
+  true,
+  "+01:00",
+  Symbol(),
+  3600_000_000_000n,
+  {},
+  { valueOf() { return 3600_000_000_000; } },
+].forEach((wrongOffset) => {
+  const timeZone = TemporalHelpers.specificOffsetTimeZone(wrongOffset);
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone);
+  assert.throws(TypeError, () => time.until(datetime));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/balance-negative-time-units.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/balance-negative-time-units.js
new file mode 100644
index 0000000000..f843b547cf
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/balance-negative-time-units.js
@@ -0,0 +1,51 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Negative time fields are balanced upwards
+info: |
+    sec-temporal-balancetime steps 3–14:
+      3. Set _microsecond_ to _microsecond_ + floor(_nanosecond_ / 1000).
+      4. Set _nanosecond_ to _nanosecond_ modulo 1000.
+      5. Set _millisecond_ to _millisecond_ + floor(_microsecond_ / 1000).
+      6. Set _microsecond_ to _microsecond_ modulo 1000.
+      7. Set _second_ to _second_ + floor(_millisecond_ / 1000).
+      8. Set _millisecond_ to _millisecond_ modulo 1000.
+      9. Set _minute_ to _minute_ + floor(_second_ / 60).
+      10. Set _second_ to _second_ modulo 60.
+      11. Set _hour_ to _hour_ + floor(_minute_ / 60).
+      12. Set _minute_ to _minute_ modulo 60.
+      13. Let _days_ be floor(_hour_ / 24).
+      14. Set _hour_ to _hour_ modulo 24.
+    sec-temporal-differencetime step 8:
+      8. Let _bt_ be ? BalanceTime(_hours_, _minutes_, _seconds_, _milliseconds_, _microseconds_, _nanoseconds_).
+    sec-temporal.plaintime.prototype.until step 11:
+      11. Let _result_ be ! DifferenceTime(_temporalTime_.[[ISOHour]], _temporalTime_.[[ISOMinute]], _temporalTime_.[[ISOSecond]], _temporalTime_.[[ISOMillisecond]], _temporalTime_.[[ISOMicrosecond]], _temporalTime_.[[ISONanosecond]], _other_.[[ISOHour]], _other_.[[ISOMinute]], _other_.[[ISOSecond]], _other_.[[ISOMillisecond]], _other_.[[ISOMicrosecond]], _other_.[[ISONanosecond]]).
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(1, 1, 1, 1, 1, 1);
+
+const result1 = new Temporal.PlainTime(0, 0, 0, 0, 0, 2).until(time);
+TemporalHelpers.assertDuration(result1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 999, "nanoseconds balance");
+
+const result2 = new Temporal.PlainTime(0, 0, 0, 0, 2).until(time);
+TemporalHelpers.assertDuration(result2, 0, 0, 0, 0, 1, 1, 1, 0, 999, 1, "microseconds balance");
+
+const result3 = new Temporal.PlainTime(0, 0, 0, 2).until(time);
+TemporalHelpers.assertDuration(result3, 0, 0, 0, 0, 1, 1, 0, 999, 1, 1, "milliseconds balance");
+
+const result4 = new Temporal.PlainTime(0, 0, 2).until(time);
+TemporalHelpers.assertDuration(result4, 0, 0, 0, 0, 1, 0, 59, 1, 1, 1, "seconds balance");
+
+const result5 = new Temporal.PlainTime(0, 2).until(time);
+TemporalHelpers.assertDuration(result5, 0, 0, 0, 0, 0, 59, 1, 1, 1, 1, "minutes balance");
+
+// This one is different because hours are later balanced again in BalanceDuration
+const result6 = new Temporal.PlainTime(2).until(time);
+TemporalHelpers.assertDuration(result6, 0, 0, 0, 0, 0, -58, -58, -998, -998, -999, "hours balance");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/basic.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/basic.js
new file mode 100644
index 0000000000..25fcdaf427
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/basic.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Basic usage
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const one = new Temporal.PlainTime(15, 23, 30, 123, 456, 789);
+const two = new Temporal.PlainTime(16, 23, 30, 123, 456, 789);
+const three = new Temporal.PlainTime(17, 0, 30, 123, 456, 789);
+
+TemporalHelpers.assertDuration(one.until(two),
+  0, 0, 0, 0, /* hours = */ 1, 0, 0, 0, 0, 0);
+TemporalHelpers.assertDuration(two.until(one),
+  0, 0, 0, 0, /* hours = */ -1, 0, 0, 0, 0, 0);
+TemporalHelpers.assertDuration(one.until(three),
+  0, 0, 0, 0, /* hours = */ 1, 37, 0, 0, 0, 0);
+TemporalHelpers.assertDuration(three.until(one),
+  0, 0, 0, 0, /* hours = */ -1, -37, 0, 0, 0, 0);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/branding.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/branding.js
new file mode 100644
index 0000000000..3bb9a732f1
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/branding.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Throw a TypeError if the receiver is invalid
+features: [Symbol, Temporal]
+---*/
+
+const until = Temporal.PlainTime.prototype.until;
+
+assert.sameValue(typeof until, "function");
+
+const args = [new Temporal.PlainTime(12)];
+
+assert.throws(TypeError, () => until.apply(undefined, args), "undefined");
+assert.throws(TypeError, () => until.apply(null, args), "null");
+assert.throws(TypeError, () => until.apply(true, args), "true");
+assert.throws(TypeError, () => until.apply("", args), "empty string");
+assert.throws(TypeError, () => until.apply(Symbol(), args), "symbol");
+assert.throws(TypeError, () => until.apply(1, args), "1");
+assert.throws(TypeError, () => until.apply({}, args), "plain object");
+assert.throws(TypeError, () => until.apply(Temporal.PlainTime, args), "Temporal.PlainTime");
+assert.throws(TypeError, () => until.apply(Temporal.PlainTime.prototype, args), "Temporal.PlainTime.prototype");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/builtin.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/builtin.js
new file mode 100644
index 0000000000..791d6abf1d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/builtin.js
@@ -0,0 +1,36 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: >
+    Tests that Temporal.PlainTime.prototype.until
+    meets the requirements for built-in objects defined by the
+    introduction of chapter 17 of the ECMAScript Language Specification.
+info: |
+    Built-in functions that are not constructors do not have a "prototype" property unless
+    otherwise specified in the description of a particular function.
+
+    Unless specified otherwise, a built-in object that is callable as a function is a built-in
+    function object with the characteristics described in 10.3. Unless specified otherwise, the
+    [[Extensible]] internal slot of a built-in object initially has the value true.
+
+    Unless otherwise specified every built-in function and every built-in constructor has the
+    Function prototype object [...] as the value of its [[Prototype]] internal slot.
+features: [Temporal]
+---*/
+
+assert.sameValue(Object.isExtensible(Temporal.PlainTime.prototype.until),
+  true, "Built-in objects must be extensible.");
+
+assert.sameValue(Object.prototype.toString.call(Temporal.PlainTime.prototype.until),
+  "[object Function]", "Object.prototype.toString");
+
+assert.sameValue(Object.getPrototypeOf(Temporal.PlainTime.prototype.until),
+  Function.prototype, "prototype");
+
+assert.sameValue(Temporal.PlainTime.prototype.until.hasOwnProperty("prototype"),
+  false, "prototype property");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/calendar-temporal-object.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/calendar-temporal-object.js
new file mode 100644
index 0000000000..73bd0c05e9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/calendar-temporal-object.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Fast path for converting other Temporal objects to Temporal.Calendar by reading internal slots
+info: |
+    sec-temporal.plaintime.prototype.until step 3:
+      3. Set _other_ to ? ToTemporalTime(_other_).
+    sec-temporal-totemporaltime step 3.d:
+      d. If _calendar_ is not *undefined*, then
+        i. Set _calendar_ to ? ToTemporalCalendar(_calendar_).
+        ii. If ? ToString(_calendar_) is not *"iso8601"*, then
+          1. Throw a *RangeError* exception.
+    sec-temporal-totemporalcalendar step 1.a:
+      a. If _temporalCalendarLike_ has an [[InitializedTemporalDate]], [[InitializedTemporalDateTime]], [[InitializedTemporalMonthDay]], [[InitializedTemporalYearMonth]], or [[InitializedTemporalZonedDateTime]] internal slot, then
+        i. Return _temporalCalendarLike_.[[Calendar]].
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+TemporalHelpers.checkToTemporalCalendarFastPath((temporalObject) => {
+  const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+  assert.throws(RangeError, () => time.until({ hour: 12, minute: 30, calendar: temporalObject }));
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/largestunit-invalid-string.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/largestunit-invalid-string.js
new file mode 100644
index 0000000000..cb344782d4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/largestunit-invalid-string.js
@@ -0,0 +1,39 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: RangeError thrown when largestUnit option not one of the allowed string values
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 0, 0, 0);
+const later = new Temporal.PlainTime(13, 35, 57, 987, 654, 321);
+const badValues = [
+  "era",
+  "eraYear",
+  "year",
+  "month",
+  "week",
+  "day",
+  "millisecond\0",
+  "mill\u0131second",
+  "SECOND",
+  "eras",
+  "eraYears",
+  "years",
+  "months",
+  "weeks",
+  "days",
+  "milliseconds\0",
+  "mill\u0131seconds",
+  "SECONDS",
+  "other string"
+];
+for (const largestUnit of badValues) {
+  assert.throws(RangeError, () => earlier.until(later, { largestUnit }),
+    `"${largestUnit}" is not a valid value for largestUnit`);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/largestunit-plurals-accepted.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/largestunit-plurals-accepted.js
new file mode 100644
index 0000000000..9438b68d03
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/largestunit-plurals-accepted.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Plural units are accepted as well for the largestUnit option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+const later = new Temporal.PlainTime(13, 35, 57, 988, 655, 322);
+const validUnits = [
+  "hour",
+  "minute",
+  "second",
+  "millisecond",
+  "microsecond",
+  "nanosecond",
+];
+TemporalHelpers.checkPluralUnitsAccepted((largestUnit) => earlier.until(later, { largestUnit }), validUnits);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/largestunit-smallestunit-mismatch.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/largestunit-smallestunit-mismatch.js
new file mode 100644
index 0000000000..a30e4684b5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/largestunit-smallestunit-mismatch.js
@@ -0,0 +1,22 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: RangeError thrown when smallestUnit is larger than largestUnit
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 0, 0, 0);
+const later = new Temporal.PlainTime(13, 35, 57, 987, 654, 321);
+const units = ["hours", "minutes", "seconds", "milliseconds", "microseconds", "nanoseconds"];
+for (let largestIdx = 1; largestIdx < units.length; largestIdx++) {
+  for (let smallestIdx = 0; smallestIdx < largestIdx; smallestIdx++) {
+    const largestUnit = units[largestIdx];
+    const smallestUnit = units[smallestIdx];
+    assert.throws(RangeError, () => earlier.until(later, { largestUnit, smallestUnit }));
+  }
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/largestunit-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/largestunit-undefined.js
new file mode 100644
index 0000000000..6b895c9c82
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/largestunit-undefined.js
@@ -0,0 +1,20 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Fallback value for largestUnit option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 0, 0, 0);
+const later = new Temporal.PlainTime(13, 35, 57, 987, 654, 321);
+
+const explicit = earlier.until(later, { largestUnit: undefined });
+TemporalHelpers.assertDuration(explicit, 0, 0, 0, 0, 1, 1, 1, 987, 654, 321, "default largestUnit is hour");
+const implicit = earlier.until(later, {});
+TemporalHelpers.assertDuration(implicit, 0, 0, 0, 0, 1, 1, 1, 987, 654, 321, "default largestUnit is hour");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/largestunit-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/largestunit-wrong-type.js
new file mode 100644
index 0000000000..a3afa56d7f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/largestunit-wrong-type.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Type conversions for largestUnit option
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 0, 0, 0);
+const later = new Temporal.PlainTime(13, 35, 57, 987, 654, 321);
+TemporalHelpers.checkStringOptionWrongType("largestUnit", "second",
+  (largestUnit) => earlier.until(later, { largestUnit }),
+  (result, descr) => TemporalHelpers.assertDuration(result, 0, 0, 0, 0, 0, 0, 3661, 987, 654, 321, descr),
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/largestunit.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/largestunit.js
new file mode 100644
index 0000000000..28d07834d8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/largestunit.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: PlainTime.until with various largestUnit values.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+const fourFortyEight = new Temporal.PlainTime(4, 48, 55);
+const elevenFiftyNine = new Temporal.PlainTime(11, 59, 58);
+TemporalHelpers.assertDuration(fourFortyEight.until(elevenFiftyNine), 0, 0, 0, 0, 7, 11, 3, 0, 0, 0, "does not include higher units than necessary (largest unit unspecified)");
+TemporalHelpers.assertDuration(fourFortyEight.until(elevenFiftyNine, { largestUnit: "auto" }), 0, 0, 0, 0, 7, 11, 3, 0, 0, 0,  "does not include higher units than necessary (largest unit is auto)");
+TemporalHelpers.assertDuration(fourFortyEight.until(elevenFiftyNine, { largestUnit: "hours" }), 0, 0, 0, 0, 7, 11, 3, 0, 0, 0,  "does not include higher units than necessary (largest unit is hours)");
+TemporalHelpers.assertDuration(fourFortyEight.until(elevenFiftyNine, { largestUnit: "minutes" }), 0, 0, 0, 0, 0, 431, 3, 0, 0, 0, "does not include higher units than necessary (largest unit is minutes)");
+TemporalHelpers.assertDuration(fourFortyEight.until(elevenFiftyNine, { largestUnit: "seconds" }), 0, 0, 0, 0, 0, 0, 25863, 0, 0, 0, "does not include higher units than necessary (largest unit is seconds)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/leap-second.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/leap-second.js
new file mode 100644
index 0000000000..a6d6a8ff59
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/leap-second.js
@@ -0,0 +1,30 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Leap second is a valid ISO string for PlainTime
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(23, 59, 59);
+
+let arg = "2016-12-31T23:59:60";
+const result1 = instance.until(arg);
+TemporalHelpers.assertDuration(
+  result1,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  "leap second is a valid ISO string for PlainTime"
+);
+
+arg = { year: 2016, month: 12, day: 31, hour: 23, minute: 59, second: 60 };
+const result2 = instance.until(arg);
+TemporalHelpers.assertDuration(
+  result2,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  "second: 60 is ignored in property bag for PlainTime"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/length.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/length.js
new file mode 100644
index 0000000000..52df3730c9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/length.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Temporal.PlainTime.prototype.until.length is 1
+info: |
+    Every built-in function object, including constructors, has a "length" property whose value is
+    an integer. Unless otherwise specified, this value is equal to the largest number of named
+    arguments shown in the subclause headings for the function description. Optional parameters
+    (which are indicated with brackets: [ ]) or rest parameters (which are shown using the form
+    «...name») are not included in the default argument count.
+
+    Unless otherwise specified, the "length" property of a built-in function object has the
+    attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.until, "length", {
+  value: 1,
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/name.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/name.js
new file mode 100644
index 0000000000..ffa71815de
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/name.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Temporal.PlainTime.prototype.until.name is "until".
+info: |
+    Every built-in function object, including constructors, that is not identified as an anonymous
+    function has a "name" property whose value is a String. Unless otherwise specified, this value
+    is the name that is given to the function in this specification.
+
+    Unless otherwise specified, the "name" property of a built-in function object, if it exists,
+    has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.until, "name", {
+  value: "until",
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/not-a-constructor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/not-a-constructor.js
new file mode 100644
index 0000000000..5b19fde1f2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/not-a-constructor.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: >
+  Temporal.PlainTime.prototype.until does not implement [[Construct]], is not new-able
+info: |
+    Built-in function objects that are not identified as constructors do not implement the
+    [[Construct]] internal method unless otherwise specified in the description of a particular
+    function.
+includes: [isConstructor.js]
+features: [Reflect.construct, Temporal]
+---*/
+
+assert.throws(TypeError, () => {
+  new Temporal.PlainTime.prototype.until();
+}, "Calling as constructor");
+
+assert.sameValue(isConstructor(Temporal.PlainTime.prototype.until), false,
+  "isConstructor(Temporal.PlainTime.prototype.until)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/options-invalid.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/options-invalid.js
new file mode 100644
index 0000000000..7f1b6d124a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/options-invalid.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: TypeError thrown when a primitive is passed as the options argument
+features: [Temporal]
+---*/
+
+const values = [null, true, "hello", Symbol("foo"), 1, 1n];
+const time = new Temporal.PlainTime(15, 23, 30, 123, 456, 789);
+const one = new Temporal.PlainTime(16, 23, 30, 123, 456, 789);
+
+for (const badOptions of values) {
+  assert.throws(TypeError, () => time.until(one, badOptions));
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/options-object.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/options-object.js
new file mode 100644
index 0000000000..8c40ef9512
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/options-object.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Empty or a function object may be used as options
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime();
+
+const result1 = instance.until(new Temporal.PlainTime(12, 34, 56), {});
+TemporalHelpers.assertDuration(
+  result1, 0, 0, 0, 0, 12, 34, 56, 0, 0, 0,
+  "options may be an empty plain object"
+);
+
+const result2 = instance.until(new Temporal.PlainTime(12, 34, 56), () => {});
+TemporalHelpers.assertDuration(
+  result2, 0, 0, 0, 0, 12, 34, 56, 0, 0, 0,
+  "options may be a function object"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/options-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/options-undefined.js
new file mode 100644
index 0000000000..d0160e162c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/options-undefined.js
@@ -0,0 +1,22 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Verify that undefined options are handled correctly.
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+const later = new Temporal.PlainTime(18, 34, 56, 987, 654, 322);
+
+const explicit = earlier.until(later, undefined);
+assert.sameValue(explicit.hours, 6, "default largest unit is hours");
+assert.sameValue(explicit.nanoseconds, 1, "default smallest unit is nanoseconds and no rounding");
+
+const implicit = earlier.until(later);
+assert.sameValue(implicit.hours, 6, "default largest unit is hours");
+assert.sameValue(implicit.nanoseconds, 1, "default smallest unit is nanoseconds and no rounding");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/options-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/options-wrong-type.js
new file mode 100644
index 0000000000..5de1440564
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/options-wrong-type.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: TypeError thrown when options argument is a primitive
+features: [BigInt, Symbol, Temporal]
+---*/
+
+const badOptions = [
+  null,
+  true,
+  "some string",
+  Symbol(),
+  1,
+  2n,
+];
+
+const instance = new Temporal.PlainTime();
+for (const value of badOptions) {
+  assert.throws(TypeError, () => instance.until(new Temporal.PlainTime(12, 34, 56), value),
+    `TypeError on wrong options type ${typeof value}`);
+};
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/order-of-operations.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/order-of-operations.js
new file mode 100644
index 0000000000..c142313ba4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/order-of-operations.js
@@ -0,0 +1,82 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Properties on an object passed to until() are accessed in the correct order
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const expected = [
+  // ToTemporalTime
+  "get other.calendar",
+  "get other.calendar.toString",
+  "call other.calendar.toString",
+  "get other.hour",
+  "get other.hour.valueOf",
+  "call other.hour.valueOf",
+  "get other.microsecond",
+  "get other.microsecond.valueOf",
+  "call other.microsecond.valueOf",
+  "get other.millisecond",
+  "get other.millisecond.valueOf",
+  "call other.millisecond.valueOf",
+  "get other.minute",
+  "get other.minute.valueOf",
+  "call other.minute.valueOf",
+  "get other.nanosecond",
+  "get other.nanosecond.valueOf",
+  "call other.nanosecond.valueOf",
+  "get other.second",
+  "get other.second.valueOf",
+  "call other.second.valueOf",
+  // CopyDataProperties
+  "ownKeys options",
+  "getOwnPropertyDescriptor options.roundingIncrement",
+  "get options.roundingIncrement",
+  "getOwnPropertyDescriptor options.roundingMode",
+  "get options.roundingMode",
+  "getOwnPropertyDescriptor options.largestUnit",
+  "get options.largestUnit",
+  "getOwnPropertyDescriptor options.smallestUnit",
+  "get options.smallestUnit",
+  "getOwnPropertyDescriptor options.additional",
+  "get options.additional",
+  // GetDifferenceSettings
+  "get options.largestUnit.toString",
+  "call options.largestUnit.toString",
+  "get options.roundingIncrement.valueOf",
+  "call options.roundingIncrement.valueOf",
+  "get options.roundingMode.toString",
+  "call options.roundingMode.toString",
+  "get options.smallestUnit.toString",
+  "call options.smallestUnit.toString",
+];
+const actual = [];
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const other = TemporalHelpers.propertyBagObserver(actual, {
+  hour: 1.7,
+  minute: 1.7,
+  second: 1.7,
+  millisecond: 1.7,
+  microsecond: 1.7,
+  nanosecond: 1.7,
+  calendar: "iso8601",
+}, "other");
+
+const options = TemporalHelpers.propertyBagObserver(actual, {
+  roundingIncrement: 1,
+  roundingMode: "trunc",
+  largestUnit: "hours",
+  smallestUnit: "nanoseconds",
+  additional: true,
+}, "options");
+
+const result = instance.until(other, options);
+assert.compareArray(actual, expected, "order of operations");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/plaintime-propertybag-no-time-units.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/plaintime-propertybag-no-time-units.js
new file mode 100644
index 0000000000..c23221629a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/plaintime-propertybag-no-time-units.js
@@ -0,0 +1,21 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Missing time units in property bag default to 0
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(1, 0, 0, 0, 0, 1);
+
+const props = {};
+assert.throws(TypeError, () => instance.until(props), "TypeError if no properties are present");
+
+props.minute = 30;
+const result = instance.until(props);
+TemporalHelpers.assertDuration(result, 0, 0, 0, 0, 0, -30, 0, 0, 0, -1, "missing time units default to 0");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/prop-desc.js
new file mode 100644
index 0000000000..e22bbfa49c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/prop-desc.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: The "until" property of Temporal.PlainTime.prototype
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+assert.sameValue(
+  typeof Temporal.PlainTime.prototype.until,
+  "function",
+  "`typeof PlainTime.prototype.until` is `function`"
+);
+
+verifyProperty(Temporal.PlainTime.prototype, "until", {
+  writable: true,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/result-sub-second.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/result-sub-second.js
new file mode 100644
index 0000000000..4488fb67eb
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/result-sub-second.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Supports sub-second precision
+includes: [temporalHelpers.js]
+features: [Temporal, arrow-function]
+---*/
+
+const time1 = Temporal.PlainTime.from("10:23:15");
+const time2 = Temporal.PlainTime.from("17:15:57.250250250");
+
+TemporalHelpers.assertDuration(time1.until(time2, { largestUnit: "milliseconds" }),
+  0, 0, 0, 0, 0, 0, 0, /* milliseconds = */ 24762250, 250, 250, "milliseconds");
+
+TemporalHelpers.assertDuration(time1.until(time2, { largestUnit: "microseconds" }),
+  0, 0, 0, 0, 0, 0, 0, /* milliseconds = */ 0, 24762250250, 250, "microseconds");
+
+TemporalHelpers.assertDuration(time1.until(time2, { largestUnit: "nanoseconds" }),
+  0, 0, 0, 0, 0, 0, 0, /* milliseconds = */ 0, 0, 24762250250250, "nanoseconds");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-hours.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-hours.js
new file mode 100644
index 0000000000..23ce813182
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-hours.js
@@ -0,0 +1,37 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Valid values for roundingIncrement option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(3, 12, 34, 123, 456, 789);
+const later = new Temporal.PlainTime(13, 47, 57, 988, 655, 322);
+
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "hours", roundingIncrement: 1 }),
+  0, 0, 0, 0, 10, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "hours", roundingIncrement: 2 }),
+  0, 0, 0, 0, 10, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "hours", roundingIncrement: 3 }),
+  0, 0, 0, 0, 9, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "hours", roundingIncrement: 4 }),
+  0, 0, 0, 0, 8, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "hours", roundingIncrement: 6 }),
+  0, 0, 0, 0, 6, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "hours", roundingIncrement: 8 }),
+  0, 0, 0, 0, 8, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "hours", roundingIncrement: 12 }),
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, "hours");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-invalid.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-invalid.js
new file mode 100644
index 0000000000..d24005b1ff
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-invalid.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Tests roundingIncrement restrictions.
+features: [Temporal]
+---*/
+
+const earlier = Temporal.PlainTime.from("08:22:36.123456789");
+const later = Temporal.PlainTime.from("12:39:40.987654321");
+
+assert.throws(RangeError, () => earlier.until(later, { smallestUnit: "hours", roundingIncrement: 11 }));
+assert.throws(RangeError, () => earlier.until(later, { smallestUnit: "minutes", roundingIncrement: 29 }));
+assert.throws(RangeError, () => earlier.until(later, { smallestUnit: "seconds", roundingIncrement: 29 }));
+assert.throws(RangeError, () => earlier.until(later, { smallestUnit: "milliseconds", roundingIncrement: 29 }));
+assert.throws(RangeError, () => earlier.until(later, { smallestUnit: "microseconds", roundingIncrement: 29 }));
+assert.throws(RangeError, () => earlier.until(later, { smallestUnit: "nanoseconds", roundingIncrement: 29 }));
+assert.throws(RangeError, () => earlier.until(later, { smallestUnit: "hours", roundingIncrement: 24 }));
+assert.throws(RangeError, () => earlier.until(later, { smallestUnit: "minutes", roundingIncrement: 60 }));
+assert.throws(RangeError, () => earlier.until(later, { smallestUnit: "seconds", roundingIncrement: 60 }));
+assert.throws(RangeError, () => earlier.until(later, { smallestUnit: "milliseconds", roundingIncrement: 1000 }));
+assert.throws(RangeError, () => earlier.until(later, { smallestUnit: "microseconds", roundingIncrement: 1000 }));
+assert.throws(RangeError, () => earlier.until(later, { smallestUnit: "nanoseconds", roundingIncrement: 1000 }));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-microseconds.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-microseconds.js
new file mode 100644
index 0000000000..4814ada190
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-microseconds.js
@@ -0,0 +1,61 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Valid values for roundingIncrement option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(3, 12, 34, 123, 456, 789);
+const later = new Temporal.PlainTime(13, 47, 57, 988, 655, 322);
+
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "microseconds", roundingIncrement: 1 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "microseconds", roundingIncrement: 2 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "microseconds", roundingIncrement: 4 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 196, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "microseconds", roundingIncrement: 5 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 195, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "microseconds", roundingIncrement: 8 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 192, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "microseconds", roundingIncrement: 10 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 190, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "microseconds", roundingIncrement: 20 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 180, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "microseconds", roundingIncrement: 25 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 175, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "microseconds", roundingIncrement: 40 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 160, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "microseconds", roundingIncrement: 50 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 150, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "microseconds", roundingIncrement: 100 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 100, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "microseconds", roundingIncrement: 125 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 125, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "microseconds", roundingIncrement: 200 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 0, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "microseconds", roundingIncrement: 250 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 0, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "microseconds", roundingIncrement: 500 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 0, 0, "microseconds");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-milliseconds.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-milliseconds.js
new file mode 100644
index 0000000000..c9d49c4a0f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-milliseconds.js
@@ -0,0 +1,61 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Valid values for roundingIncrement option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(3, 12, 34, 123, 456, 789);
+const later = new Temporal.PlainTime(13, 47, 57, 988, 655, 322);
+
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "milliseconds", roundingIncrement: 1 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "milliseconds", roundingIncrement: 2 }),
+  0, 0, 0, 0, 10, 35, 23, 864, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "milliseconds", roundingIncrement: 4 }),
+  0, 0, 0, 0, 10, 35, 23, 864, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "milliseconds", roundingIncrement: 5 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "milliseconds", roundingIncrement: 8 }),
+  0, 0, 0, 0, 10, 35, 23, 864, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "milliseconds", roundingIncrement: 10 }),
+  0, 0, 0, 0, 10, 35, 23, 860, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "milliseconds", roundingIncrement: 20 }),
+  0, 0, 0, 0, 10, 35, 23, 860, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "milliseconds", roundingIncrement: 25 }),
+  0, 0, 0, 0, 10, 35, 23, 850, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "milliseconds", roundingIncrement: 40 }),
+  0, 0, 0, 0, 10, 35, 23, 840, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "milliseconds", roundingIncrement: 50 }),
+  0, 0, 0, 0, 10, 35, 23, 850, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "milliseconds", roundingIncrement: 100 }),
+  0, 0, 0, 0, 10, 35, 23, 800, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "milliseconds", roundingIncrement: 125 }),
+  0, 0, 0, 0, 10, 35, 23, 750, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "milliseconds", roundingIncrement: 200 }),
+  0, 0, 0, 0, 10, 35, 23, 800, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "milliseconds", roundingIncrement: 250 }),
+  0, 0, 0, 0, 10, 35, 23, 750, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "milliseconds", roundingIncrement: 500 }),
+  0, 0, 0, 0, 10, 35, 23, 500, 0, 0, "milliseconds");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-minutes.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-minutes.js
new file mode 100644
index 0000000000..928488a8e9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-minutes.js
@@ -0,0 +1,49 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Valid values for roundingIncrement option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(3, 12, 34, 123, 456, 789);
+const later = new Temporal.PlainTime(13, 47, 57, 988, 655, 322);
+
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "minutes", roundingIncrement: 1 }),
+  0, 0, 0, 0, 10, 35, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "minutes", roundingIncrement: 2 }),
+  0, 0, 0, 0, 10, 34, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "minutes", roundingIncrement: 3 }),
+  0, 0, 0, 0, 10, 33, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "minutes", roundingIncrement: 4 }),
+  0, 0, 0, 0, 10, 32, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "minutes", roundingIncrement: 5 }),
+  0, 0, 0, 0, 10, 35, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "minutes", roundingIncrement: 6 }),
+  0, 0, 0, 0, 10, 30, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "minutes", roundingIncrement: 10 }),
+  0, 0, 0, 0, 10, 30, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "minutes", roundingIncrement: 12 }),
+  0, 0, 0, 0, 10, 24, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "minutes", roundingIncrement: 15 }),
+  0, 0, 0, 0, 10, 30, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "minutes", roundingIncrement: 20 }),
+  0, 0, 0, 0, 10, 20, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "minutes", roundingIncrement: 30 }),
+  0, 0, 0, 0, 10, 30, 0, 0, 0, 0, "minutes");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-nan.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-nan.js
new file mode 100644
index 0000000000..b36cd7605f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-nan.js
@@ -0,0 +1,22 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: RangeError thrown when roundingIncrement option is NaN
+info: |
+    sec-getoption step 8.b:
+      b. If _value_ is *NaN*, throw a *RangeError* exception.
+    sec-temporal-totemporalroundingincrement step 5:
+      5. Let _increment_ be ? GetOption(_normalizedOptions_, *"roundingIncrement"*, « Number », *undefined*, 1).
+    sec-temporal.plaintime.prototype.until step 10:
+      10. Let _roundingIncrement_ be ? ToTemporalRoundingIncrement(_options_, _maximum_, *false*).
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+const later = new Temporal.PlainTime(13, 35, 57, 988, 655, 322);
+assert.throws(RangeError, () => earlier.until(later, { roundingIncrement: NaN }));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-nanoseconds.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-nanoseconds.js
new file mode 100644
index 0000000000..e67633b28a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-nanoseconds.js
@@ -0,0 +1,61 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Valid values for roundingIncrement option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(3, 12, 34, 123, 456, 789);
+const later = new Temporal.PlainTime(13, 47, 57, 988, 655, 322);
+
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "nanoseconds", roundingIncrement: 1 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 533, "nanoseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "nanoseconds", roundingIncrement: 2 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 532, "nanoseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "nanoseconds", roundingIncrement: 4 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 532, "nanoseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "nanoseconds", roundingIncrement: 5 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 530, "nanoseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "nanoseconds", roundingIncrement: 8 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 528, "nanoseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "nanoseconds", roundingIncrement: 10 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 530, "nanoseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "nanoseconds", roundingIncrement: 20 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 520, "nanoseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "nanoseconds", roundingIncrement: 25 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 525, "nanoseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "nanoseconds", roundingIncrement: 40 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 520, "nanoseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "nanoseconds", roundingIncrement: 50 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 500, "nanoseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "nanoseconds", roundingIncrement: 100 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 500, "nanoseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "nanoseconds", roundingIncrement: 125 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 500, "nanoseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "nanoseconds", roundingIncrement: 200 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 400, "nanoseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "nanoseconds", roundingIncrement: 250 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 500, "nanoseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "nanoseconds", roundingIncrement: 500 }),
+  0, 0, 0, 0, 10, 35, 23, 865, 198, 500, "nanoseconds");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-non-integer.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-non-integer.js
new file mode 100644
index 0000000000..98b1d80b57
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-non-integer.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Rounding for roundingIncrement option
+info: |
+    ToTemporalRoundingIncrement ( _normalizedOptions_ )
+
+    1. Let _increment_ be ? GetOption(_normalizedOptions_, *"roundingIncrement"*, *"number"*, *undefined*, *1*<sub>𝔽</sub>).
+    2. If _increment_ is not finite, throw a *RangeError* exception.
+    3. Let _integerIncrement_ be truncate(ℝ(_increment_)).
+    4. If _integerIncrement_ < 1 or _integerIncrement_ > 10<sup>9</sup>, throw a *RangeError* exception.
+    5. Return _integerIncrement_.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 0, 0, 0);
+const later = new Temporal.PlainTime(12, 34, 56, 0, 0, 5);
+const result = earlier.until(later, { roundingIncrement: 2.5, roundingMode: "trunc" });
+TemporalHelpers.assertDuration(result, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, "roundingIncrement 2.5 truncates to 2");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-out-of-range.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-out-of-range.js
new file mode 100644
index 0000000000..8be1599792
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-out-of-range.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: RangeError thrown when roundingIncrement option out of range
+info: |
+    ToTemporalRoundingIncrement ( _normalizedOptions_ )
+
+    1. Let _increment_ be ? GetOption(_normalizedOptions_, *"roundingIncrement"*, *"number"*, *undefined*, *1*<sub>𝔽</sub>).
+    2. If _increment_ is not finite, throw a *RangeError* exception.
+    3. Let _integerIncrement_ be truncate(ℝ(_increment_)).
+    4. If _integerIncrement_ < 1 or _integerIncrement_ > 10<sup>9</sup>, throw a *RangeError* exception.
+    5. Return _integerIncrement_.
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 0, 0, 0);
+const later = new Temporal.PlainTime(12, 34, 56, 0, 0, 5);
+assert.throws(RangeError, () => earlier.until(later, { roundingIncrement: -Infinity }));
+assert.throws(RangeError, () => earlier.until(later, { roundingIncrement: -1 }));
+assert.throws(RangeError, () => earlier.until(later, { roundingIncrement: 0 }));
+assert.throws(RangeError, () => earlier.until(later, { roundingIncrement: 0.9 }));
+assert.throws(RangeError, () => earlier.until(later, { roundingIncrement: 1e9 + 1 }));
+assert.throws(RangeError, () => earlier.until(later, { roundingIncrement: Infinity }));
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-seconds.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-seconds.js
new file mode 100644
index 0000000000..1dc8b53a66
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-seconds.js
@@ -0,0 +1,49 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Valid values for roundingIncrement option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(3, 12, 34, 123, 456, 789);
+const later = new Temporal.PlainTime(13, 47, 57, 988, 655, 322);
+
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "seconds", roundingIncrement: 1 }),
+  0, 0, 0, 0, 10, 35, 23, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "seconds", roundingIncrement: 2 }),
+  0, 0, 0, 0, 10, 35, 22, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "seconds", roundingIncrement: 3 }),
+  0, 0, 0, 0, 10, 35, 21, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "seconds", roundingIncrement: 4 }),
+  0, 0, 0, 0, 10, 35, 20, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "seconds", roundingIncrement: 5 }),
+  0, 0, 0, 0, 10, 35, 20, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "seconds", roundingIncrement: 6 }),
+  0, 0, 0, 0, 10, 35, 18, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "seconds", roundingIncrement: 10 }),
+  0, 0, 0, 0, 10, 35, 20, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "seconds", roundingIncrement: 12 }),
+  0, 0, 0, 0, 10, 35, 12, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "seconds", roundingIncrement: 15 }),
+  0, 0, 0, 0, 10, 35, 15, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "seconds", roundingIncrement: 20 }),
+  0, 0, 0, 0, 10, 35, 20, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "seconds", roundingIncrement: 30 }),
+  0, 0, 0, 0, 10, 35, 0, 0, 0, 0, "seconds");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-undefined.js
new file mode 100644
index 0000000000..ceb69689da
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-undefined.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Fallback value for roundingIncrement option
+info: |
+    sec-getoption step 3:
+      3. If _value_ is *undefined*, return _fallback_.
+    sec-temporal-totemporalroundingincrement step 5:
+      5. Let _increment_ be ? GetOption(_normalizedOptions_, *"roundingIncrement"*, « Number », *undefined*, 1).
+    sec-temporal.plaintime.prototype.until step 10:
+      10. Let _roundingIncrement_ be ? ToTemporalRoundingIncrement(_options_, _maximum_, *false*).
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+const later = new Temporal.PlainTime(13, 35, 57, 988, 655, 322);
+
+const explicit = earlier.until(later, { roundingIncrement: undefined });
+TemporalHelpers.assertDuration(explicit, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, "default roundingIncrement is 1");
+
+const implicit = earlier.until(later, {});
+TemporalHelpers.assertDuration(implicit, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, "default roundingIncrement is 1");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-wrong-type.js
new file mode 100644
index 0000000000..2492807ea8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingincrement-wrong-type.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Type conversions for roundingIncrement option
+info: |
+    sec-getoption step 8.a:
+      a. Set _value_ to ? ToNumber(value).
+    sec-temporal-totemporalroundingincrement step 5:
+      5. Let _increment_ be ? GetOption(_normalizedOptions_, *"roundingIncrement"*, « Number », *undefined*, 1).
+    sec-temporal.plaintime.prototype.until step 10:
+      10. Let _roundingIncrement_ be ? ToTemporalRoundingIncrement(_options_, _maximum_, *false*).
+includes: [temporalHelpers.js, compareArray.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+const later = new Temporal.PlainTime(13, 35, 57, 988, 655, 322);
+
+TemporalHelpers.checkRoundingIncrementOptionWrongType(
+  (roundingIncrement) => earlier.until(later, { roundingIncrement }),
+  (result, descr) => TemporalHelpers.assertDuration(result, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, descr),
+  (result, descr) => TemporalHelpers.assertDuration(result, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, descr),
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-ceil.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-ceil.js
new file mode 100644
index 0000000000..891a9aebd5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-ceil.js
@@ -0,0 +1,41 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Tests calculations with roundingMode "ceil".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(8, 22, 36, 123, 456, 789);
+const later = new Temporal.PlainTime(12, 39, 40, 987, 654, 289);
+
+const expected = [
+  ["hours", [0, 0, 0, 0, 5], [0, 0, 0, 0, -4]],
+  ["minutes", [0, 0, 0, 0, 4, 18], [0, 0, 0, 0, -4, -17]],
+  ["seconds", [0, 0, 0, 0, 4, 17, 5], [0, 0, 0, 0, -4, -17, -4]],
+  ["milliseconds", [0, 0, 0, 0, 4, 17, 4, 865], [0, 0, 0, 0, -4, -17, -4, -864]],
+  ["microseconds", [0, 0, 0, 0, 4, 17, 4, 864, 198], [0, 0, 0, 0, -4, -17, -4, -864, -197]],
+  ["nanoseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197, 500], [0, 0, 0, 0, -4, -17, -4, -864, -197, -500]],
+];
+
+const roundingMode = "ceil";
+
+expected.forEach(([smallestUnit, expectedPositive, expectedNegative]) => {
+  const [py, pm = 0, pw = 0, pd = 0, ph = 0, pmin = 0, ps = 0, pms = 0, pµs = 0, pns = 0] = expectedPositive;
+  const [ny, nm = 0, nw = 0, nd = 0, nh = 0, nmin = 0, ns = 0, nms = 0, nµs = 0, nns = 0] = expectedNegative;
+  TemporalHelpers.assertDuration(
+    earlier.until(later, { smallestUnit, roundingMode }),
+    py, pm, pw, pd, ph, pmin, ps, pms, pµs, pns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode}, positive case)`
+  );
+  TemporalHelpers.assertDuration(
+    later.until(earlier, { smallestUnit, roundingMode }),
+    ny, nm, nw, nd, nh, nmin, ns, nms, nµs, nns,
+    `rounds to ${smallestUnit} (rounding mode = ${roundingMode}, negative case)`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-expand.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-expand.js
new file mode 100644
index 0000000000..3f91016d90
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-expand.js
@@ -0,0 +1,41 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Tests calculations with roundingMode "expand".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(8, 22, 36, 123, 456, 789);
+const later = new Temporal.PlainTime(12, 39, 40, 987, 654, 289);
+
+const expected = [
+  ["hours", [0, 0, 0, 0, 5], [0, 0, 0, 0, -5]],
+  ["minutes", [0, 0, 0, 0, 4, 18], [0, 0, 0, 0, -4, -18]],
+  ["seconds", [0, 0, 0, 0, 4, 17, 5], [0, 0, 0, 0, -4, -17, -5]],
+  ["milliseconds", [0, 0, 0, 0, 4, 17, 4, 865], [0, 0, 0, 0, -4, -17, -4, -865]],
+  ["microseconds", [0, 0, 0, 0, 4, 17, 4, 864, 198], [0, 0, 0, 0, -4, -17, -4, -864, -198]],
+  ["nanoseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197, 500], [0, 0, 0, 0, -4, -17, -4, -864, -197, -500]],
+];
+
+const roundingMode = "expand";
+
+expected.forEach(([smallestUnit, expectedPositive, expectedNegative]) => {
+  const [py, pm = 0, pw = 0, pd = 0, ph = 0, pmin = 0, ps = 0, pms = 0, pµs = 0, pns = 0] = expectedPositive;
+  const [ny, nm = 0, nw = 0, nd = 0, nh = 0, nmin = 0, ns = 0, nms = 0, nµs = 0, nns = 0] = expectedNegative;
+  TemporalHelpers.assertDuration(
+    earlier.until(later, { smallestUnit, roundingMode }),
+    py, pm, pw, pd, ph, pmin, ps, pms, pµs, pns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode}, positive case)`
+  );
+  TemporalHelpers.assertDuration(
+    later.until(earlier, { smallestUnit, roundingMode }),
+    ny, nm, nw, nd, nh, nmin, ns, nms, nµs, nns,
+    `rounds to ${smallestUnit} (rounding mode = ${roundingMode}, negative case)`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-floor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-floor.js
new file mode 100644
index 0000000000..b6a8e11d4c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-floor.js
@@ -0,0 +1,41 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Tests calculations with roundingMode "floor".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(8, 22, 36, 123, 456, 789);
+const later = new Temporal.PlainTime(12, 39, 40, 987, 654, 289);
+
+const expected = [
+  ["hours", [0, 0, 0, 0, 4], [0, 0, 0, 0, -5]],
+  ["minutes", [0, 0, 0, 0, 4, 17], [0, 0, 0, 0, -4, -18]],
+  ["seconds", [0, 0, 0, 0, 4, 17, 4], [0, 0, 0, 0, -4, -17, -5]],
+  ["milliseconds", [0, 0, 0, 0, 4, 17, 4, 864], [0, 0, 0, 0, -4, -17, -4, -865]],
+  ["microseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197], [0, 0, 0, 0, -4, -17, -4, -864, -198]],
+  ["nanoseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197, 500], [0, 0, 0, 0, -4, -17, -4, -864, -197, -500]],
+];
+
+const roundingMode = "floor";
+
+expected.forEach(([smallestUnit, expectedPositive, expectedNegative]) => {
+  const [py, pm = 0, pw = 0, pd = 0, ph = 0, pmin = 0, ps = 0, pms = 0, pµs = 0, pns = 0] = expectedPositive;
+  const [ny, nm = 0, nw = 0, nd = 0, nh = 0, nmin = 0, ns = 0, nms = 0, nµs = 0, nns = 0] = expectedNegative;
+  TemporalHelpers.assertDuration(
+    earlier.until(later, { smallestUnit, roundingMode }),
+    py, pm, pw, pd, ph, pmin, ps, pms, pµs, pns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode}, positive case)`
+  );
+  TemporalHelpers.assertDuration(
+    later.until(earlier, { smallestUnit, roundingMode }),
+    ny, nm, nw, nd, nh, nmin, ns, nms, nµs, nns,
+    `rounds to ${smallestUnit} (rounding mode = ${roundingMode}, negative case)`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-halfCeil.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-halfCeil.js
new file mode 100644
index 0000000000..aa131b1924
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-halfCeil.js
@@ -0,0 +1,41 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Tests calculations with roundingMode "halfCeil".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(8, 22, 36, 123, 456, 789);
+const later = new Temporal.PlainTime(12, 39, 40, 987, 654, 289);
+
+const expected = [
+  ["hours", [0, 0, 0, 0, 4], [0, 0, 0, 0, -4]],
+  ["minutes", [0, 0, 0, 0, 4, 17], [0, 0, 0, 0, -4, -17]],
+  ["seconds", [0, 0, 0, 0, 4, 17, 5], [0, 0, 0, 0, -4, -17, -5]],
+  ["milliseconds", [0, 0, 0, 0, 4, 17, 4, 864], [0, 0, 0, 0, -4, -17, -4, -864]],
+  ["microseconds", [0, 0, 0, 0, 4, 17, 4, 864, 198], [0, 0, 0, 0, -4, -17, -4, -864, -197]],
+  ["nanoseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197, 500], [0, 0, 0, 0, -4, -17, -4, -864, -197, -500]],
+];
+
+const roundingMode = "halfCeil";
+
+expected.forEach(([smallestUnit, expectedPositive, expectedNegative]) => {
+  const [py, pm = 0, pw = 0, pd = 0, ph = 0, pmin = 0, ps = 0, pms = 0, pµs = 0, pns = 0] = expectedPositive;
+  const [ny, nm = 0, nw = 0, nd = 0, nh = 0, nmin = 0, ns = 0, nms = 0, nµs = 0, nns = 0] = expectedNegative;
+  TemporalHelpers.assertDuration(
+    earlier.until(later, { smallestUnit, roundingMode }),
+    py, pm, pw, pd, ph, pmin, ps, pms, pµs, pns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode}, positive case)`
+  );
+  TemporalHelpers.assertDuration(
+    later.until(earlier, { smallestUnit, roundingMode }),
+    ny, nm, nw, nd, nh, nmin, ns, nms, nµs, nns,
+    `rounds to ${smallestUnit} (rounding mode = ${roundingMode}, negative case)`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-halfEven.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-halfEven.js
new file mode 100644
index 0000000000..e0f57c3572
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-halfEven.js
@@ -0,0 +1,41 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Tests calculations with roundingMode "halfEven".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(8, 22, 36, 123, 456, 789);
+const later = new Temporal.PlainTime(12, 39, 40, 987, 654, 289);
+
+const expected = [
+  ["hours", [0, 0, 0, 0, 4], [0, 0, 0, 0, -4]],
+  ["minutes", [0, 0, 0, 0, 4, 17], [0, 0, 0, 0, -4, -17]],
+  ["seconds", [0, 0, 0, 0, 4, 17, 5], [0, 0, 0, 0, -4, -17, -5]],
+  ["milliseconds", [0, 0, 0, 0, 4, 17, 4, 864], [0, 0, 0, 0, -4, -17, -4, -864]],
+  ["microseconds", [0, 0, 0, 0, 4, 17, 4, 864, 198], [0, 0, 0, 0, -4, -17, -4, -864, -198]],
+  ["nanoseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197, 500], [0, 0, 0, 0, -4, -17, -4, -864, -197, -500]],
+];
+
+const roundingMode = "halfEven";
+
+expected.forEach(([smallestUnit, expectedPositive, expectedNegative]) => {
+  const [py, pm = 0, pw = 0, pd = 0, ph = 0, pmin = 0, ps = 0, pms = 0, pµs = 0, pns = 0] = expectedPositive;
+  const [ny, nm = 0, nw = 0, nd = 0, nh = 0, nmin = 0, ns = 0, nms = 0, nµs = 0, nns = 0] = expectedNegative;
+  TemporalHelpers.assertDuration(
+    earlier.until(later, { smallestUnit, roundingMode }),
+    py, pm, pw, pd, ph, pmin, ps, pms, pµs, pns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode}, positive case)`
+  );
+  TemporalHelpers.assertDuration(
+    later.until(earlier, { smallestUnit, roundingMode }),
+    ny, nm, nw, nd, nh, nmin, ns, nms, nµs, nns,
+    `rounds to ${smallestUnit} (rounding mode = ${roundingMode}, negative case)`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-halfExpand.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-halfExpand.js
new file mode 100644
index 0000000000..1f49dc2525
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-halfExpand.js
@@ -0,0 +1,41 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Tests calculations with roundingMode "halfExpand".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(8, 22, 36, 123, 456, 789);
+const later = new Temporal.PlainTime(12, 39, 40, 987, 654, 289);
+
+const expected = [
+  ["hours", [0, 0, 0, 0, 4], [0, 0, 0, 0, -4]],
+  ["minutes", [0, 0, 0, 0, 4, 17], [0, 0, 0, 0, -4, -17]],
+  ["seconds", [0, 0, 0, 0, 4, 17, 5], [0, 0, 0, 0, -4, -17, -5]],
+  ["milliseconds", [0, 0, 0, 0, 4, 17, 4, 864], [0, 0, 0, 0, -4, -17, -4, -864]],
+  ["microseconds", [0, 0, 0, 0, 4, 17, 4, 864, 198], [0, 0, 0, 0, -4, -17, -4, -864, -198]],
+  ["nanoseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197, 500], [0, 0, 0, 0, -4, -17, -4, -864, -197, -500]],
+];
+
+const roundingMode = "halfExpand";
+
+expected.forEach(([smallestUnit, expectedPositive, expectedNegative]) => {
+  const [py, pm = 0, pw = 0, pd = 0, ph = 0, pmin = 0, ps = 0, pms = 0, pµs = 0, pns = 0] = expectedPositive;
+  const [ny, nm = 0, nw = 0, nd = 0, nh = 0, nmin = 0, ns = 0, nms = 0, nµs = 0, nns = 0] = expectedNegative;
+  TemporalHelpers.assertDuration(
+    earlier.until(later, { smallestUnit, roundingMode }),
+    py, pm, pw, pd, ph, pmin, ps, pms, pµs, pns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode}, positive case)`
+  );
+  TemporalHelpers.assertDuration(
+    later.until(earlier, { smallestUnit, roundingMode }),
+    ny, nm, nw, nd, nh, nmin, ns, nms, nµs, nns,
+    `rounds to ${smallestUnit} (rounding mode = ${roundingMode}, negative case)`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-halfFloor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-halfFloor.js
new file mode 100644
index 0000000000..79c326a3ff
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-halfFloor.js
@@ -0,0 +1,41 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Tests calculations with roundingMode "halfFloor".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(8, 22, 36, 123, 456, 789);
+const later = new Temporal.PlainTime(12, 39, 40, 987, 654, 289);
+
+const expected = [
+  ["hours", [0, 0, 0, 0, 4], [0, 0, 0, 0, -4]],
+  ["minutes", [0, 0, 0, 0, 4, 17], [0, 0, 0, 0, -4, -17]],
+  ["seconds", [0, 0, 0, 0, 4, 17, 5], [0, 0, 0, 0, -4, -17, -5]],
+  ["milliseconds", [0, 0, 0, 0, 4, 17, 4, 864], [0, 0, 0, 0, -4, -17, -4, -864]],
+  ["microseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197], [0, 0, 0, 0, -4, -17, -4, -864, -198]],
+  ["nanoseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197, 500], [0, 0, 0, 0, -4, -17, -4, -864, -197, -500]],
+];
+
+const roundingMode = "halfFloor";
+
+expected.forEach(([smallestUnit, expectedPositive, expectedNegative]) => {
+  const [py, pm = 0, pw = 0, pd = 0, ph = 0, pmin = 0, ps = 0, pms = 0, pµs = 0, pns = 0] = expectedPositive;
+  const [ny, nm = 0, nw = 0, nd = 0, nh = 0, nmin = 0, ns = 0, nms = 0, nµs = 0, nns = 0] = expectedNegative;
+  TemporalHelpers.assertDuration(
+    earlier.until(later, { smallestUnit, roundingMode }),
+    py, pm, pw, pd, ph, pmin, ps, pms, pµs, pns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode}, positive case)`
+  );
+  TemporalHelpers.assertDuration(
+    later.until(earlier, { smallestUnit, roundingMode }),
+    ny, nm, nw, nd, nh, nmin, ns, nms, nµs, nns,
+    `rounds to ${smallestUnit} (rounding mode = ${roundingMode}, negative case)`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-halfTrunc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-halfTrunc.js
new file mode 100644
index 0000000000..0711eb60ac
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-halfTrunc.js
@@ -0,0 +1,41 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Tests calculations with roundingMode "halfTrunc".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(8, 22, 36, 123, 456, 789);
+const later = new Temporal.PlainTime(12, 39, 40, 987, 654, 289);
+
+const expected = [
+  ["hours", [0, 0, 0, 0, 4], [0, 0, 0, 0, -4]],
+  ["minutes", [0, 0, 0, 0, 4, 17], [0, 0, 0, 0, -4, -17]],
+  ["seconds", [0, 0, 0, 0, 4, 17, 5], [0, 0, 0, 0, -4, -17, -5]],
+  ["milliseconds", [0, 0, 0, 0, 4, 17, 4, 864], [0, 0, 0, 0, -4, -17, -4, -864]],
+  ["microseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197], [0, 0, 0, 0, -4, -17, -4, -864, -197]],
+  ["nanoseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197, 500], [0, 0, 0, 0, -4, -17, -4, -864, -197, -500]],
+];
+
+const roundingMode = "halfTrunc";
+
+expected.forEach(([smallestUnit, expectedPositive, expectedNegative]) => {
+  const [py, pm = 0, pw = 0, pd = 0, ph = 0, pmin = 0, ps = 0, pms = 0, pµs = 0, pns = 0] = expectedPositive;
+  const [ny, nm = 0, nw = 0, nd = 0, nh = 0, nmin = 0, ns = 0, nms = 0, nµs = 0, nns = 0] = expectedNegative;
+  TemporalHelpers.assertDuration(
+    earlier.until(later, { smallestUnit, roundingMode }),
+    py, pm, pw, pd, ph, pmin, ps, pms, pµs, pns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode}, positive case)`
+  );
+  TemporalHelpers.assertDuration(
+    later.until(earlier, { smallestUnit, roundingMode }),
+    ny, nm, nw, nd, nh, nmin, ns, nms, nµs, nns,
+    `rounds to ${smallestUnit} (rounding mode = ${roundingMode}, negative case)`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-invalid-string.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-invalid-string.js
new file mode 100644
index 0000000000..e1285d52c8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-invalid-string.js
@@ -0,0 +1,17 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: RangeError thrown when roundingMode option not one of the allowed string values
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 0, 0, 0);
+const later = new Temporal.PlainTime(13, 35, 57, 123, 987, 500);
+for (const roundingMode of ["other string", "cile", "CEIL", "ce\u0131l", "auto", "halfexpand", "floor\0"]) {
+  assert.throws(RangeError, () => earlier.until(later, { smallestUnit: "microsecond", roundingMode }));
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-trunc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-trunc.js
new file mode 100644
index 0000000000..b847abc205
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-trunc.js
@@ -0,0 +1,41 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Tests calculations with roundingMode "trunc".
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(8, 22, 36, 123, 456, 789);
+const later = new Temporal.PlainTime(12, 39, 40, 987, 654, 289);
+
+const expected = [
+  ["hours", [0, 0, 0, 0, 4], [0, 0, 0, 0, -4]],
+  ["minutes", [0, 0, 0, 0, 4, 17], [0, 0, 0, 0, -4, -17]],
+  ["seconds", [0, 0, 0, 0, 4, 17, 4], [0, 0, 0, 0, -4, -17, -4]],
+  ["milliseconds", [0, 0, 0, 0, 4, 17, 4, 864], [0, 0, 0, 0, -4, -17, -4, -864]],
+  ["microseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197], [0, 0, 0, 0, -4, -17, -4, -864, -197]],
+  ["nanoseconds", [0, 0, 0, 0, 4, 17, 4, 864, 197, 500], [0, 0, 0, 0, -4, -17, -4, -864, -197, -500]],
+];
+
+const roundingMode = "trunc";
+
+expected.forEach(([smallestUnit, expectedPositive, expectedNegative]) => {
+  const [py, pm = 0, pw = 0, pd = 0, ph = 0, pmin = 0, ps = 0, pms = 0, pµs = 0, pns = 0] = expectedPositive;
+  const [ny, nm = 0, nw = 0, nd = 0, nh = 0, nmin = 0, ns = 0, nms = 0, nµs = 0, nns = 0] = expectedNegative;
+  TemporalHelpers.assertDuration(
+    earlier.until(later, { smallestUnit, roundingMode }),
+    py, pm, pw, pd, ph, pmin, ps, pms, pµs, pns,
+    `rounds to ${smallestUnit} (roundingMode = ${roundingMode}, positive case)`
+  );
+  TemporalHelpers.assertDuration(
+    later.until(earlier, { smallestUnit, roundingMode }),
+    ny, nm, nw, nd, nh, nmin, ns, nms, nµs, nns,
+    `rounds to ${smallestUnit} (rounding mode = ${roundingMode}, negative case)`
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-undefined.js
new file mode 100644
index 0000000000..c339dd94f2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-undefined.js
@@ -0,0 +1,93 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Fallback value for roundingMode option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = Temporal.PlainTime.from("08:22:36.123456789");
+const later = Temporal.PlainTime.from("12:39:40.987654321");
+
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "hours", roundingMode: undefined }),
+  0, 0, 0, 0, 4, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "hours" }),
+  0, 0, 0, 0, 4, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertDuration(
+  later.until(earlier, { smallestUnit: "hours", roundingMode: undefined }),
+  0, 0, 0, 0, -4, 0, 0, 0, 0, 0, "hours");
+TemporalHelpers.assertDuration(
+  later.until(earlier, { smallestUnit: "hours" }),
+  0, 0, 0, 0, -4, 0, 0, 0, 0, 0, "hours");
+
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "minutes", roundingMode: undefined }),
+  0, 0, 0, 0, 4, 17, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "minutes" }),
+  0, 0, 0, 0, 4, 17, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  later.until(earlier, { smallestUnit: "minutes", roundingMode: undefined }),
+  0, 0, 0, 0, -4, -17, 0, 0, 0, 0, "minutes");
+TemporalHelpers.assertDuration(
+  later.until(earlier, { smallestUnit: "minutes" }),
+  0, 0, 0, 0, -4, -17, 0, 0, 0, 0, "minutes");
+
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "seconds", roundingMode: undefined }),
+  0, 0, 0, 0, 4, 17, 4, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "seconds" }),
+  0, 0, 0, 0, 4, 17, 4, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  later.until(earlier, { smallestUnit: "seconds", roundingMode: undefined }),
+  0, 0, 0, 0, -4, -17, -4, 0, 0, 0, "seconds");
+TemporalHelpers.assertDuration(
+  later.until(earlier, { smallestUnit: "seconds" }),
+  0, 0, 0, 0, -4, -17, -4, 0, 0, 0, "seconds");
+
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "milliseconds", roundingMode: undefined }),
+  0, 0, 0, 0, 4, 17, 4, 864, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "milliseconds" }),
+  0, 0, 0, 0, 4, 17, 4, 864, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  later.until(earlier, { smallestUnit: "milliseconds", roundingMode: undefined }),
+  0, 0, 0, 0, -4, -17, -4, -864, 0, 0, "milliseconds");
+TemporalHelpers.assertDuration(
+  later.until(earlier, { smallestUnit: "milliseconds" }),
+  0, 0, 0, 0, -4, -17, -4, -864, 0, 0, "milliseconds");
+
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "microseconds", roundingMode: undefined }),
+  0, 0, 0, 0, 4, 17, 4, 864, 197, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "microseconds" }),
+  0, 0, 0, 0, 4, 17, 4, 864, 197, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  later.until(earlier, { smallestUnit: "microseconds", roundingMode: undefined }),
+  0, 0, 0, 0, -4, -17, -4, -864, -197, 0, "microseconds");
+TemporalHelpers.assertDuration(
+  later.until(earlier, { smallestUnit: "microseconds" }),
+  0, 0, 0, 0, -4, -17, -4, -864, -197, 0, "microseconds");
+
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "nanoseconds", roundingMode: undefined }),
+  0, 0, 0, 0, 4, 17, 4, 864, 197, 532, "nanoseconds");
+TemporalHelpers.assertDuration(
+  earlier.until(later, { smallestUnit: "nanoseconds" }),
+  0, 0, 0, 0, 4, 17, 4, 864, 197, 532, "nanoseconds");
+TemporalHelpers.assertDuration(
+  later.until(earlier, { smallestUnit: "nanoseconds", roundingMode: undefined }),
+  0, 0, 0, 0, -4, -17, -4, -864, -197, -532, "nanoseconds");
+TemporalHelpers.assertDuration(
+  later.until(earlier, { smallestUnit: "nanoseconds" }),
+  0, 0, 0, 0, -4, -17, -4, -864, -197, -532, "nanoseconds");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-wrong-type.js
new file mode 100644
index 0000000000..454a995e7a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/roundingmode-wrong-type.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Type conversions for roundingMode option
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 0, 0, 0);
+const later = new Temporal.PlainTime(13, 35, 57, 123, 987, 500);
+TemporalHelpers.checkStringOptionWrongType("roundingMode", "trunc",
+  (roundingMode) => earlier.until(later, { smallestUnit: "microsecond", roundingMode }),
+  (result, descr) => TemporalHelpers.assertDuration(result, 0, 0, 0, 0, 1, 1, 1, 123, 987, 0, descr),
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/smallestunit-invalid-string.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/smallestunit-invalid-string.js
new file mode 100644
index 0000000000..0de577d404
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/smallestunit-invalid-string.js
@@ -0,0 +1,39 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: RangeError thrown when smallestUnit option not one of the allowed string values
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 0, 0, 0);
+const later = new Temporal.PlainTime(13, 35, 57, 987, 654, 321);
+const badValues = [
+  "era",
+  "eraYear",
+  "year",
+  "month",
+  "week",
+  "day",
+  "millisecond\0",
+  "mill\u0131second",
+  "SECOND",
+  "eras",
+  "eraYears",
+  "years",
+  "months",
+  "weeks",
+  "days",
+  "milliseconds\0",
+  "mill\u0131seconds",
+  "SECONDS",
+  "other string",
+];
+for (const smallestUnit of badValues) {
+  assert.throws(RangeError, () => earlier.until(later, { smallestUnit }),
+    `"${smallestUnit}" is not a valid value for smallest unit`);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/smallestunit-plurals-accepted.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/smallestunit-plurals-accepted.js
new file mode 100644
index 0000000000..3cf5c2a43e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/smallestunit-plurals-accepted.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Plural units are accepted as well for the smallestUnit option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+const later = new Temporal.PlainTime(13, 35, 57, 988, 655, 322);
+const validUnits = [
+  "hour",
+  "minute",
+  "second",
+  "millisecond",
+  "microsecond",
+  "nanosecond",
+];
+TemporalHelpers.checkPluralUnitsAccepted((smallestUnit) => earlier.until(later, { smallestUnit }), validUnits);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/smallestunit-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/smallestunit-undefined.js
new file mode 100644
index 0000000000..6b03b807ff
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/smallestunit-undefined.js
@@ -0,0 +1,22 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Fallback value for smallestUnit option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 0, 0, 0);
+const later = new Temporal.PlainTime(13, 35, 57, 987, 654, 321);
+
+const explicit = earlier.until(later, { smallestUnit: undefined });
+TemporalHelpers.assertDuration(explicit, 0, 0, 0, 0, 1, 1, 1, 987, 654, 321, "default smallestUnit is nanosecond");
+const implicit = earlier.until(later, {});
+TemporalHelpers.assertDuration(implicit, 0, 0, 0, 0, 1, 1, 1, 987, 654, 321, "default smallestUnit is nanosecond");
+const lambda = earlier.until(later, () => {});
+TemporalHelpers.assertDuration(lambda, 0, 0, 0, 0, 1, 1, 1, 987, 654, 321, "default smallestUnit is nanosecond");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/smallestunit-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/smallestunit-wrong-type.js
new file mode 100644
index 0000000000..a5619b8878
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/smallestunit-wrong-type.js
@@ -0,0 +1,19 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Type conversions for smallestUnit option
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime(12, 34, 56, 0, 0, 0);
+const later = new Temporal.PlainTime(13, 35, 57, 987, 654, 321);
+TemporalHelpers.checkStringOptionWrongType("smallestUnit", "microsecond",
+  (smallestUnit) => earlier.until(later, { smallestUnit }),
+  (result, descr) => TemporalHelpers.assertDuration(result, 0, 0, 0, 0, 1, 1, 1, 987, 654, 0, descr),
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/year-zero.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/year-zero.js
new file mode 100644
index 0000000000..fbe1c448a0
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/until/year-zero.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Negative zero, as an extended year, is rejected
+features: [Temporal, arrow-function]
+---*/
+
+const invalidStrings = [
+  "-000000-12-07T03:24:30",
+  "-000000-12-07T03:24:30+01:00",
+  "-000000-12-07T03:24:30+00:00[UTC]",
+];
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+invalidStrings.forEach((arg) => {
+  assert.throws(
+    RangeError,
+    () => instance.until(arg),
+    "reject minus zero as extended year"
+  );
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/basic.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/basic.js
new file mode 100644
index 0000000000..64672f5beb
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/basic.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.valueof
+description: Basic tests for valueOf().
+features: [Temporal]
+---*/
+
+const plainTime = Temporal.PlainTime.from("09:36:29.123456789");
+const plainTime2 = Temporal.PlainTime.from("09:36:29.123456789");
+
+assert.throws(TypeError, () => plainTime.valueOf(), "valueOf");
+assert.throws(TypeError, () => plainTime < plainTime, "<");
+assert.throws(TypeError, () => plainTime <= plainTime, "<=");
+assert.throws(TypeError, () => plainTime > plainTime, ">");
+assert.throws(TypeError, () => plainTime >= plainTime, ">=");
+assert.sameValue(plainTime === plainTime, true, "===");
+assert.sameValue(plainTime === plainTime2, false, "===");
+assert.sameValue(plainTime !== plainTime, false, "!==");
+assert.sameValue(plainTime !== plainTime2, true, "!==");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/branding.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/branding.js
new file mode 100644
index 0000000000..73dbd79387
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/branding.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.valueof
+description: Throw a TypeError if the receiver is invalid
+features: [Symbol, Temporal]
+---*/
+
+const valueOf = Temporal.PlainTime.prototype.valueOf;
+
+assert.sameValue(typeof valueOf, "function");
+
+assert.throws(TypeError, () => valueOf.call(undefined), "undefined");
+assert.throws(TypeError, () => valueOf.call(null), "null");
+assert.throws(TypeError, () => valueOf.call(true), "true");
+assert.throws(TypeError, () => valueOf.call(""), "empty string");
+assert.throws(TypeError, () => valueOf.call(Symbol()), "symbol");
+assert.throws(TypeError, () => valueOf.call(1), "1");
+assert.throws(TypeError, () => valueOf.call({}), "plain object");
+assert.throws(TypeError, () => valueOf.call(Temporal.PlainTime), "Temporal.PlainTime");
+assert.throws(TypeError, () => valueOf.call(Temporal.PlainTime.prototype), "Temporal.PlainTime.prototype");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/builtin.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/builtin.js
new file mode 100644
index 0000000000..f46b29f58f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/builtin.js
@@ -0,0 +1,36 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.valueof
+description: >
+    Tests that Temporal.PlainTime.prototype.valueOf
+    meets the requirements for built-in objects defined by the
+    introduction of chapter 17 of the ECMAScript Language Specification.
+info: |
+    Built-in functions that are not constructors do not have a "prototype" property unless
+    otherwise specified in the description of a particular function.
+
+    Unless specified otherwise, a built-in object that is callable as a function is a built-in
+    function object with the characteristics described in 10.3. Unless specified otherwise, the
+    [[Extensible]] internal slot of a built-in object initially has the value true.
+
+    Unless otherwise specified every built-in function and every built-in constructor has the
+    Function prototype object [...] as the value of its [[Prototype]] internal slot.
+features: [Temporal]
+---*/
+
+assert.sameValue(Object.isExtensible(Temporal.PlainTime.prototype.valueOf),
+  true, "Built-in objects must be extensible.");
+
+assert.sameValue(Object.prototype.toString.call(Temporal.PlainTime.prototype.valueOf),
+  "[object Function]", "Object.prototype.toString");
+
+assert.sameValue(Object.getPrototypeOf(Temporal.PlainTime.prototype.valueOf),
+  Function.prototype, "prototype");
+
+assert.sameValue(Temporal.PlainTime.prototype.valueOf.hasOwnProperty("prototype"),
+  false, "prototype property");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/length.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/length.js
new file mode 100644
index 0000000000..71133142c0
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/length.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.valueof
+description: Temporal.PlainTime.prototype.valueOf.length is 0
+info: |
+    Every built-in function object, including constructors, has a "length" property whose value is
+    an integer. Unless otherwise specified, this value is equal to the largest number of named
+    arguments shown in the subclause headings for the function description. Optional parameters
+    (which are indicated with brackets: [ ]) or rest parameters (which are shown using the form
+    «...name») are not included in the default argument count.
+
+    Unless otherwise specified, the "length" property of a built-in function object has the
+    attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.valueOf, "length", {
+  value: 0,
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/name.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/name.js
new file mode 100644
index 0000000000..e7f50f75fc
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/name.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.valueof
+description: Temporal.PlainTime.prototype.valueOf.name is "valueOf".
+info: |
+    Every built-in function object, including constructors, that is not identified as an anonymous
+    function has a "name" property whose value is a String. Unless otherwise specified, this value
+    is the name that is given to the function in this specification.
+
+    Unless otherwise specified, the "name" property of a built-in function object, if it exists,
+    has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.valueOf, "name", {
+  value: "valueOf",
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/not-a-constructor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/not-a-constructor.js
new file mode 100644
index 0000000000..0d8e6cb64f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/not-a-constructor.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.valueof
+description: >
+  Temporal.PlainTime.prototype.valueOf does not implement [[Construct]], is not new-able
+info: |
+    Built-in function objects that are not identified as constructors do not implement the
+    [[Construct]] internal method unless otherwise specified in the description of a particular
+    function.
+includes: [isConstructor.js]
+features: [Reflect.construct, Temporal]
+---*/
+
+assert.throws(TypeError, () => {
+  new Temporal.PlainTime.prototype.valueOf();
+}, "Calling as constructor");
+
+assert.sameValue(isConstructor(Temporal.PlainTime.prototype.valueOf), false,
+  "isConstructor(Temporal.PlainTime.prototype.valueOf)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/prop-desc.js
new file mode 100644
index 0000000000..9ab2c2e48e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/prop-desc.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.valueof
+description: The "valueOf" property of Temporal.PlainTime.prototype
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+assert.sameValue(
+  typeof Temporal.PlainTime.prototype.valueOf,
+  "function",
+  "`typeof PlainTime.prototype.valueOf` is `function`"
+);
+
+verifyProperty(Temporal.PlainTime.prototype, "valueOf", {
+  writable: true,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/valueOf/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/argument-not-object.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/argument-not-object.js
new file mode 100644
index 0000000000..105336fc37
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/argument-not-object.js
@@ -0,0 +1,37 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.with
+description: TypeError is thrown if a primitive is passed, including ISO strings
+info: |
+    Temporal.PlainTime.prototype.with ( temporalTimeLike [ , options ] )
+
+    3. If Type(temporalTimeLike) is not Object, then
+        a. Throw a TypeError exception.
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+assert.throws(TypeError, () => instance.with(undefined), "undefined");
+assert.throws(TypeError, () => instance.with(null), "null");
+assert.throws(TypeError, () => instance.with(true), "true");
+assert.throws(TypeError, () => instance.with(Symbol()), "symbol");
+assert.throws(TypeError, () => instance.with(1), "1");
+assert.throws(TypeError, () => instance.with(1n), "1n");
+
+const strings = [
+  "",
+  "18:05:42.577",
+  "2019-05-17T18:05:42.577",
+  "2019-05-17T18:05:42.577Z",
+  "2019-05-17",
+  "42",
+];
+for (const s of strings) {
+  assert.throws(TypeError, () => instance.with(s), s);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/basic.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/basic.js
new file mode 100644
index 0000000000..914340ab3c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/basic.js
@@ -0,0 +1,39 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.with
+description: Basic tests for with().
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const plainTime = new Temporal.PlainTime(15, 23, 30, 123, 456, 789);
+TemporalHelpers.assertPlainTime(plainTime, 15, 23, 30, 123, 456, 789, "initial");
+
+const hour = plainTime.with({ hour: 3 });
+TemporalHelpers.assertPlainTime(hour, 3, 23, 30, 123, 456, 789, "hour");
+
+const minute = plainTime.with({ minute: 3 });
+TemporalHelpers.assertPlainTime(minute, 15, 3, 30, 123, 456, 789, "minute");
+
+const second = plainTime.with({ second: 3 });
+TemporalHelpers.assertPlainTime(second, 15, 23, 3, 123, 456, 789, "second");
+
+const millisecond = plainTime.with({ millisecond: 3 });
+TemporalHelpers.assertPlainTime(millisecond, 15, 23, 30, 3, 456, 789, "millisecond");
+
+const microsecond = plainTime.with({ microsecond: 3 });
+TemporalHelpers.assertPlainTime(microsecond, 15, 23, 30, 123, 3, 789, "microsecond");
+
+const nanosecond = plainTime.with({ nanosecond: 3 });
+TemporalHelpers.assertPlainTime(nanosecond, 15, 23, 30, 123, 456, 3, "nanosecond");
+
+const combined = plainTime.with({ minute: 8, nanosecond: 3 });
+TemporalHelpers.assertPlainTime(combined, 15, 8, 30, 123, 456, 3, "combined");
+
+const plural = plainTime.with({ minutes: 8, nanosecond: 3 });
+TemporalHelpers.assertPlainTime(plural, 15, 23, 30, 123, 456, 3, "plural");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/branding.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/branding.js
new file mode 100644
index 0000000000..bc5525378f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/branding.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.with
+description: Throw a TypeError if the receiver is invalid
+features: [Symbol, Temporal]
+---*/
+
+const with_ = Temporal.PlainTime.prototype.with;
+
+assert.sameValue(typeof with_, "function");
+
+const args = [{ hour: 7 }];
+
+assert.throws(TypeError, () => with_.apply(undefined, args), "undefined");
+assert.throws(TypeError, () => with_.apply(null, args), "null");
+assert.throws(TypeError, () => with_.apply(true, args), "true");
+assert.throws(TypeError, () => with_.apply("", args), "empty string");
+assert.throws(TypeError, () => with_.apply(Symbol(), args), "symbol");
+assert.throws(TypeError, () => with_.apply(1, args), "1");
+assert.throws(TypeError, () => with_.apply({}, args), "plain object");
+assert.throws(TypeError, () => with_.apply(Temporal.PlainTime, args), "Temporal.PlainTime");
+assert.throws(TypeError, () => with_.apply(Temporal.PlainTime.prototype, args), "Temporal.PlainTime.prototype");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/browser.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/browser.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/builtin.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/builtin.js
new file mode 100644
index 0000000000..563b2814e3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/builtin.js
@@ -0,0 +1,36 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.with
+description: >
+    Tests that Temporal.PlainTime.prototype.with
+    meets the requirements for built-in objects defined by the
+    introduction of chapter 17 of the ECMAScript Language Specification.
+info: |
+    Built-in functions that are not constructors do not have a "prototype" property unless
+    otherwise specified in the description of a particular function.
+
+    Unless specified otherwise, a built-in object that is callable as a function is a built-in
+    function object with the characteristics described in 10.3. Unless specified otherwise, the
+    [[Extensible]] internal slot of a built-in object initially has the value true.
+
+    Unless otherwise specified every built-in function and every built-in constructor has the
+    Function prototype object [...] as the value of its [[Prototype]] internal slot.
+features: [Temporal]
+---*/
+
+assert.sameValue(Object.isExtensible(Temporal.PlainTime.prototype.with),
+  true, "Built-in objects must be extensible.");
+
+assert.sameValue(Object.prototype.toString.call(Temporal.PlainTime.prototype.with),
+  "[object Function]", "Object.prototype.toString");
+
+assert.sameValue(Object.getPrototypeOf(Temporal.PlainTime.prototype.with),
+  Function.prototype, "prototype");
+
+assert.sameValue(Temporal.PlainTime.prototype.with.hasOwnProperty("prototype"),
+  false, "prototype property");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/copy-properties-not-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/copy-properties-not-undefined.js
new file mode 100644
index 0000000000..3147ac4c0f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/copy-properties-not-undefined.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.with
+description: PreparePartialTemporalFields copies only defined properties of source object
+info: |
+  4. For each value _property_ of _fieldNames_, do
+    a. Let _value_ be ? Get(_fields_, _property_).
+    b. If _value_ is not *undefined*, then
+        ...
+        iii. Perform ! CreateDataPropertyOrThrow(_result_, _property_, _value_).
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const plainTime = new Temporal.PlainTime(9, 45, 55);
+
+TemporalHelpers.assertPlainTime(plainTime.with({ hour: 8, second: undefined }),
+  8, 45, 55, 0, 0, 0,
+  "only the properties that are present and defined in the plain object are copied"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/infinity-throws-rangeerror.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/infinity-throws-rangeerror.js
new file mode 100644
index 0000000000..ba2d089dfa
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/infinity-throws-rangeerror.js
@@ -0,0 +1,27 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Throws if any value in the property bag is Infinity or -Infinity
+esid: sec-temporal.plaintime.prototype.with
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+[Infinity, -Infinity].forEach((inf) => {
+  ["hour", "minute", "second", "millisecond", "microsecond", "nanosecond"].forEach((prop) => {
+    ["constrain", "reject"].forEach((overflow) => {
+      assert.throws(RangeError, () => instance.with({ [prop]: inf }, { overflow }), `${prop} property cannot be ${inf} (overflow ${overflow}`);
+
+      const calls = [];
+      const obj = TemporalHelpers.toPrimitiveObserver(calls, inf, prop);
+      assert.throws(RangeError, () => instance.with({ [prop]: obj }, { overflow }));
+      assert.compareArray(calls, [`get ${prop}.valueOf`, `call ${prop}.valueOf`], "it fails after fetching the primitive value");
+    });
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/length.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/length.js
new file mode 100644
index 0000000000..d1f23c9f78
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/length.js
@@ -0,0 +1,28 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.with
+description: Temporal.PlainTime.prototype.with.length is 1
+info: |
+    Every built-in function object, including constructors, has a "length" property whose value is
+    an integer. Unless otherwise specified, this value is equal to the largest number of named
+    arguments shown in the subclause headings for the function description. Optional parameters
+    (which are indicated with brackets: [ ]) or rest parameters (which are shown using the form
+    «...name») are not included in the default argument count.
+
+    Unless otherwise specified, the "length" property of a built-in function object has the
+    attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.with, "length", {
+  value: 1,
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/name.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/name.js
new file mode 100644
index 0000000000..6ff9a05df9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/name.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.with
+description: Temporal.PlainTime.prototype.with.name is "with".
+info: |
+    Every built-in function object, including constructors, that is not identified as an anonymous
+    function has a "name" property whose value is a String. Unless otherwise specified, this value
+    is the name that is given to the function in this specification.
+
+    Unless otherwise specified, the "name" property of a built-in function object, if it exists,
+    has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+verifyProperty(Temporal.PlainTime.prototype.with, "name", {
+  value: "with",
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/not-a-constructor.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/not-a-constructor.js
new file mode 100644
index 0000000000..15dde1eeef
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/not-a-constructor.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.with
+description: >
+  Temporal.PlainTime.prototype.with does not implement [[Construct]], is not new-able
+info: |
+    Built-in function objects that are not identified as constructors do not implement the
+    [[Construct]] internal method unless otherwise specified in the description of a particular
+    function.
+includes: [isConstructor.js]
+features: [Reflect.construct, Temporal]
+---*/
+
+assert.throws(TypeError, () => {
+  new Temporal.PlainTime.prototype.with();
+}, "Calling as constructor");
+
+assert.sameValue(isConstructor(Temporal.PlainTime.prototype.with), false,
+  "isConstructor(Temporal.PlainTime.prototype.with)");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/options-invalid.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/options-invalid.js
new file mode 100644
index 0000000000..18c1c5724d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/options-invalid.js
@@ -0,0 +1,16 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.with
+description: TypeError thrown when a primitive is passed as the options argument
+features: [Temporal]
+---*/
+
+const plainTime = new Temporal.PlainTime(12);
+for (const badOptions of [null, true, "hello", Symbol("foo"), 1, 1n]) {
+  assert.throws(TypeError, () => plainTime.with({ hour: 3 }, badOptions));
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/options-object.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/options-object.js
new file mode 100644
index 0000000000..7c371fad58
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/options-object.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.with
+description: Empty or a function object may be used as options
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime();
+
+const result1 = instance.with({ minute: 45 }, {});
+TemporalHelpers.assertPlainTime(
+  result1, 0, 45, 0, 0, 0, 0,
+  "options may be an empty plain object"
+);
+
+const result2 = instance.with({ minute: 45 }, () => {});
+TemporalHelpers.assertPlainTime(
+  result2, 0, 45, 0, 0, 0, 0,
+  "options may be a function object"
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/options-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/options-undefined.js
new file mode 100644
index 0000000000..6f42e0f26d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/options-undefined.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.with
+includes: [temporalHelpers.js]
+description: Verify that undefined options are handled correctly.
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+const fields = { minute: 60 };
+
+const explicit = time.with(fields, undefined);
+TemporalHelpers.assertPlainTime(explicit, 12, 59, 56, 987, 654, 321, "explicit");
+
+const implicit = time.with(fields);
+TemporalHelpers.assertPlainTime(implicit, 12, 59, 56, 987, 654, 321, "implicit");
+
+const lambda = time.with(fields, () => {});
+TemporalHelpers.assertPlainTime(lambda, 12, 59, 56, 987, 654, 321, "lambda");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/options-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/options-wrong-type.js
new file mode 100644
index 0000000000..335f39ac87
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/options-wrong-type.js
@@ -0,0 +1,26 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.with
+description: TypeError thrown when options argument is a primitive
+features: [BigInt, Symbol, Temporal]
+---*/
+
+const badOptions = [
+  null,
+  true,
+  "some string",
+  Symbol(),
+  1,
+  2n,
+];
+
+const instance = new Temporal.PlainTime();
+for (const value of badOptions) {
+  assert.throws(TypeError, () => instance.with({ minute: 45 }, value),
+    `TypeError on wrong options type ${typeof value}`);
+};
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/order-of-operations.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/order-of-operations.js
new file mode 100644
index 0000000000..5818757084
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/order-of-operations.js
@@ -0,0 +1,59 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.with
+description: Properties on an object passed to with() are accessed in the correct order
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+const expected = [
+  // RejectObjectWithCalendarOrTimeZone
+  "get fields.calendar",
+  "get fields.timeZone",
+  // ToTemporalOverflow
+  "get options.overflow",
+  "get options.overflow.toString",
+  "call options.overflow.toString",
+  // ToTemporalTimeRecord
+  "get fields.hour",
+  "get fields.hour.valueOf",
+  "call fields.hour.valueOf",
+  "get fields.microsecond",
+  "get fields.microsecond.valueOf",
+  "call fields.microsecond.valueOf",
+  "get fields.millisecond",
+  "get fields.millisecond.valueOf",
+  "call fields.millisecond.valueOf",
+  "get fields.minute",
+  "get fields.minute.valueOf",
+  "call fields.minute.valueOf",
+  "get fields.nanosecond",
+  "get fields.nanosecond.valueOf",
+  "call fields.nanosecond.valueOf",
+  "get fields.second",
+  "get fields.second.valueOf",
+  "call fields.second.valueOf",
+];
+const actual = [];
+
+const fields = TemporalHelpers.propertyBagObserver(actual, {
+  hour: 1.7,
+  minute: 1.7,
+  second: 1.7,
+  millisecond: 1.7,
+  microsecond: 1.7,
+  nanosecond: 1.7,
+}, "fields");
+
+const options = TemporalHelpers.propertyBagObserver(actual, {
+  overflow: "constrain",
+}, "options");
+
+const result = instance.with(fields, options);
+assert.compareArray(actual, expected, "order of operations");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/overflow-invalid-string.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/overflow-invalid-string.js
new file mode 100644
index 0000000000..7b383d25c3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/overflow-invalid-string.js
@@ -0,0 +1,29 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.with
+description: RangeError thrown when overflow option not one of the allowed string values
+info: |
+    sec-getoption step 10:
+      10. If _values_ is not *undefined* and _values_ does not contain an element equal to _value_, throw a *RangeError* exception.
+    sec-temporal-totemporaloverflow step 1:
+      1. Return ? GetOption(_normalizedOptions_, *"overflow"*, « String », « *"constrain"*, *"reject"* », *"constrain"*).
+    sec-temporal.plaintime.prototype.with step 11:
+      11. Let _overflow_ be ? ToTemporalOverflow(_options_).
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12);
+
+const badOverflows = ["", "CONSTRAIN", "balance", "other string", "constra\u0131n", "reject\0"];
+for (const overflow of badOverflows) {
+  assert.throws(
+    RangeError,
+    () => time.with({ minute: 45 }, { overflow }),
+    `invalid overflow ("${overflow}")`
+  );
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/overflow-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/overflow-undefined.js
new file mode 100644
index 0000000000..b66a7795a0
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/overflow-undefined.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.with
+description: Fallback value for overflow option
+info: |
+    sec-getoption step 3:
+      3. If _value_ is *undefined*, return _fallback_.
+    sec-temporal-totemporaloverflow step 1:
+      1. Return ? GetOption(_normalizedOptions_, *"overflow"*, « String », « *"constrain"*, *"reject"* », *"constrain"*).
+    sec-temporal.plaintime.prototype.with step 11:
+      11. Let _overflow_ be ? ToTemporalOverflow(_options_).
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12);
+const explicit = time.with({ minute: 67 }, { overflow: undefined });
+TemporalHelpers.assertPlainTime(explicit, 12, 59, 0, 0, 0, 0, "default overflow is constrain");
+const implicit = time.with({ minute: 67 }, {});
+TemporalHelpers.assertPlainTime(implicit, 12, 59, 0, 0, 0, 0, "default overflow is constrain");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/overflow-wrong-type.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/overflow-wrong-type.js
new file mode 100644
index 0000000000..546bba2a28
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/overflow-wrong-type.js
@@ -0,0 +1,25 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.with
+description: Type conversions for overflow option
+info: |
+    sec-getoption step 9.a:
+      a. Set _value_ to ? ToString(_value_).
+    sec-temporal-totemporaloverflow step 1:
+      1. Return ? GetOption(_normalizedOptions_, *"overflow"*, « String », « *"constrain"*, *"reject"* », *"constrain"*).
+    sec-temporal.plaintime.prototype.with step 11:
+      11. Let _overflow_ be ? ToTemporalOverflow(_options_).
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const time = new Temporal.PlainTime(12);
+TemporalHelpers.checkStringOptionWrongType("overflow", "constrain",
+  (overflow) => time.with({ minute: 45 }, { overflow }),
+  (result, descr) => TemporalHelpers.assertPlainTime(result, 12, 45, 0, 0, 0, 0, descr),
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/plaintimelike-invalid.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/plaintimelike-invalid.js
new file mode 100644
index 0000000000..4243d87b8a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/plaintimelike-invalid.js
@@ -0,0 +1,50 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.with
+description: Throws TypeError on an argument that is not a PlainTime-like property bag
+features: [Temporal]
+---*/
+
+const plainTime = new Temporal.PlainTime(12, 34, 56, 987, 654, 321);
+
+const tests = [
+  // Step 3.
+  [undefined],
+  [null],
+  [true],
+  ["2019-05-17"],
+  ["2019-05-17T12:34"],
+  ["2019-05-17T12:34Z"],
+  ["18:05:42.577"],
+  ["42"],
+  [Symbol(), "symbol"],
+  [42, "number"],
+  [42n, "bigint"],
+
+  // Step 4.
+  [Temporal.PlainDate.from("2019-05-17"), "PlainDate"],
+  [Temporal.PlainDateTime.from("2019-05-17T12:34"), "PlainDateTime"],
+  [Temporal.PlainMonthDay.from("2019-05-17"), "PlainMonthDay"],
+  [Temporal.PlainTime.from("12:34"), "PlainTime"],
+  [Temporal.PlainYearMonth.from("2019-05-17"), "PlainYearMonth"],
+  [Temporal.ZonedDateTime.from("2019-05-17T12:34Z[UTC]"), "ZonedDateTime"],
+
+  // Step 5-6.
+  [{ hour: 14, calendar: "iso8601" }, "calendar"],
+
+  // Step 7-8.
+  [{ hour: 14, timeZone: "UTC" }, "timeZone"],
+
+  // Step 9.
+  [{}, "empty object"],
+  [{ hours: 14 }, "only plural property"],
+];
+
+for (const [value, message = String(value)] of tests) {
+  assert.throws(TypeError, () => plainTime.with(value), message);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/prop-desc.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/prop-desc.js
new file mode 100644
index 0000000000..e3b43a3a9d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/prop-desc.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.with
+description: The "with" property of Temporal.PlainTime.prototype
+includes: [propertyHelper.js]
+features: [Temporal]
+---*/
+
+assert.sameValue(
+  typeof Temporal.PlainTime.prototype.with,
+  "function",
+  "`typeof PlainTime.prototype.with` is `function`"
+);
+
+verifyProperty(Temporal.PlainTime.prototype, "with", {
+  writable: true,
+  enumerable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/subclassing-ignored.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/subclassing-ignored.js
new file mode 100644
index 0000000000..f090edad8b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/prototype/with/subclassing-ignored.js
@@ -0,0 +1,20 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.with
+description: Objects of a subclass are never created as return values for with()
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+TemporalHelpers.checkSubclassingIgnored(
+  Temporal.PlainTime,
+  [12, 34, 56, 987, 654, 321],
+  "with",
+  [{ nanosecond: 1 }],
+  (result) => TemporalHelpers.assertPlainTime(result, 12, 34, 56, 987, 654, 1),
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/second-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/second-undefined.js
new file mode 100644
index 0000000000..5ad4e04922
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/second-undefined.js
@@ -0,0 +1,20 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime
+description: Second argument defaults to 0 if not given
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const args = [12, 34];
+
+const explicit = new Temporal.PlainTime(...args, undefined);
+TemporalHelpers.assertPlainTime(explicit, ...args, 0, 0, 0, 0, "explicit");
+
+const implicit = new Temporal.PlainTime(...args);
+TemporalHelpers.assertPlainTime(implicit, ...args, 0, 0, 0, 0, "implicit");
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/shell.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/shell.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/shell.js
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainTime/subclass.js b/js/src/tests/test262/built-ins/Temporal/PlainTime/subclass.js
new file mode 100644
index 0000000000..693ea6f52c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainTime/subclass.js
@@ -0,0 +1,21 @@
+// |reftest| skip -- Temporal is not supported
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime
+description: Test for Temporal.PlainTime subclassing.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+class CustomPlainTime extends Temporal.PlainTime {
+}
+
+const instance = new CustomPlainTime(12, 34, 56, 987, 654, 321);
+TemporalHelpers.assertPlainTime(instance, 12, 34, 56, 987, 654, 321);
+assert.sameValue(Object.getPrototypeOf(instance), CustomPlainTime.prototype, "Instance of CustomPlainTime");
+assert(instance instanceof CustomPlainTime, "Instance of CustomPlainTime");
+assert(instance instanceof Temporal.PlainTime, "Instance of Temporal.PlainTime");
+
+reportCompare(0, 0);