1 files changed, 28 insertions, 0 deletions
diff --git a/js/src/tests/test262/built-ins/Temporal/PlainYearMonth/prototype/since/builtin-calendar-no-observable-calls.js b/js/src/tests/test262/built-ins/Temporal/PlainYearMonth/prototype/since/builtin-calendar-no-observable-calls.js
new file mode 100644
index 0000000000..9332585b8c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Temporal/PlainYearMonth/prototype/since/builtin-calendar-no-observable-calls.js
@@ -0,0 +1,28 @@
+// |reftest| skip-if(!this.hasOwnProperty('Temporal')) -- Temporal is not enabled unconditionally
+// Copyright (C) 2023 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plainyearmonth.prototype.since
+description: >
+  Calling the method on an instance constructed with a builtin calendar causes
+  no observable lookups or calls to calendar methods.
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const dateUntilOriginal = Object.getOwnPropertyDescriptor(Temporal.Calendar.prototype, "dateUntil");
+Object.defineProperty(Temporal.Calendar.prototype, "dateUntil", {
+  configurable: true,
+  enumerable: false,
+  get() {
+    TemporalHelpers.assertUnreachable("dateUntil should not be looked up");
+  },
+});
+
+const instance = new Temporal.PlainYearMonth(2000, 5, "iso8601", 1);
+instance.since(new Temporal.PlainYearMonth(1999, 4));
+
+Object.defineProperty(Temporal.Calendar.prototype, "dateUntil", dateUntilOriginal);
+
+reportCompare(0, 0);