1 files changed, 34 insertions, 0 deletions
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainMonthDay/prototype/toPlainDate/copies-merge-fields-object.js b/js/src/tests/test262/built-ins/Temporal/PlainMonthDay/prototype/toPlainDate/copies-merge-fields-object.js
new file mode 100644
index 0000000000..232f3b089f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainMonthDay/prototype/toPlainDate/copies-merge-fields-object.js
@@ -0,0 +1,34 @@
+// |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.plainmonthday.prototype.toplaindate
+description: The object returned from mergeFields() is copied before being passed to monthDayFromFields().
+info: |
+    sec-temporal.plainmonthday.prototype.toplaindate steps 9 and 11:
+      9. Let _mergedFields_ be ? CalendarMergeFields(_calendar_, _fields_, _inputFields_).
+      11. Set _mergedFields_ to ? PrepareTemporalFields(_mergedFields_, _mergedFieldNames_, «»).
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const expected = [
+  "get day",
+  "get day.valueOf",
+  "call day.valueOf",
+  "get monthCode",
+  "get monthCode.toString",
+  "call monthCode.toString",
+  "get year",
+  "get year.valueOf",
+  "call year.valueOf",
+];
+
+const calendar = TemporalHelpers.calendarMergeFieldsGetters();
+const monthday = new Temporal.PlainMonthDay(3, 31, calendar);
+monthday.toPlainDate({ year: 2000 });
+
+assert.compareArray(calendar.mergeFieldsReturnOperations, expected, "getters called on mergeFields return");
+
+reportCompare(0, 0);