1 files changed, 58 insertions, 0 deletions
diff --git a/js/src/tests/test262/built-ins/Temporal/Calendar/prototype/fields/repeated-throw.js b/js/src/tests/test262/built-ins/Temporal/Calendar/prototype/fields/repeated-throw.js
new file mode 100644
index 0000000000..58bb67dc6c
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+++ b/js/src/tests/test262/built-ins/Temporal/Calendar/prototype/fields/repeated-throw.js
@@ -0,0 +1,58 @@
+// |reftest| skip-if(!this.hasOwnProperty('Temporal')) -- Temporal is not enabled unconditionally
+// Copyright (C) 2021 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.calendar.prototype.fields
+description: >
+  Temporal.Calendar.prototype.fields will throw if its input iterable yields
+  the same value twice.
+info: |
+  ## 12.4.21 Temporal.Calendar.prototype.fields ( fields )
+  1. Let calendar be the this value.
+  2. Perform ? RequireInternalSlot(calendar, [[InitializedTemporalCalendar]]).
+  4. Let iteratorRecord be ? Getiterator(fields, sync).
+  5. Let fieldNames be a new empty List.
+  6. Let next be true.
+  7. Repeat, while next is not false,
+  a. Set next to ? IteratorStep(iteratorRecord).
+  b. If next is not false, then
+  i. Let nextValue be ? IteratorValue(next).
+  iii. If fieldNames contains nextValue, then
+   1. Let completion be ThrowCompletion(a newly created RangeError object).
+   2. Return ? IteratorClose(iteratorRecord, completion).
+features: [Symbol, Symbol.iterator, Temporal, computed-property-names, generators]
+---*/
+let cal = new Temporal.Calendar("iso8601")
+let i = 0;
+const fields = {
+  *[Symbol.iterator]() {
+      yield "month";
+      i++;
+      yield "year";
+      i++;
+      yield "year";
+      i++;
+  }
+}
+assert.throws(
+    RangeError, () => cal.fields(fields), "repeated valid value should throw");
+assert.sameValue(i, 2, "Should stop at 2");
+
+// Test all valid values will throw when repeated
+[ "day", "monthCode", "month", "year" ].forEach((f) => {
+  i = 0;
+  const fields2 = {
+    *[Symbol.iterator]() {
+      yield f;
+      i++;
+      yield f;
+      i++;
+    }
+  }
+  assert.throws(
+    RangeError, () => cal.fields(fields2), "repeated valid value should throw");
+  assert.sameValue(i, 1, "Should stop at 1");
+});
+
+reportCompare(0, 0);