1 files changed, 33 insertions, 0 deletions
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainDateTime/prototype/toZonedDateTime/disambiguation-undefined.js b/js/src/tests/test262/built-ins/Temporal/PlainDateTime/prototype/toZonedDateTime/disambiguation-undefined.js
new file mode 100644
index 0000000000..81ae9ac9f9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainDateTime/prototype/toZonedDateTime/disambiguation-undefined.js
@@ -0,0 +1,33 @@
+// |reftest| skip-if(!this.hasOwnProperty('Temporal')) -- Temporal is not enabled unconditionally
+// 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.plaindatetime.prototype.tozoneddatetime
+description: Fallback value for disambiguation option
+info: |
+    sec-getoption step 3:
+      3. If _value_ is *undefined*, return _fallback_.
+    sec-temporal-totemporaldisambiguation step 1:
+      1. Return ? GetOption(_normalizedOptions_, *"disambiguation"*, « String », « *"compatible"*, *"earlier"*, *"later"*, *"reject"* », *"compatible"*).
+    sec-temporal.plaindatetime.prototype.tozoneddatetime step 5:
+      5. Let _disambiguation_ be ? ToTemporalDisambiguation(_options_).
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const timeZone = TemporalHelpers.springForwardFallBackTimeZone();
+const springForwardDatetime = new Temporal.PlainDateTime(2000, 4, 2, 2, 30);
+const fallBackDatetime = new Temporal.PlainDateTime(2000, 10, 29, 1, 30);
+
+[
+  [springForwardDatetime, 954671400_000_000_000n],
+  [fallBackDatetime, 972808200_000_000_000n],
+].forEach(([datetime, expected]) => {
+  const explicit = datetime.toZonedDateTime(timeZone, { disambiguation: undefined });
+  assert.sameValue(explicit.epochNanoseconds, expected, "default disambiguation is compatible");
+  const implicit = datetime.toZonedDateTime(timeZone, {});
+  assert.sameValue(implicit.epochNanoseconds, expected, "default disambiguation is compatible");
+});
+
+reportCompare(0, 0);