Add extra tests for newly fixed bug

test/built-ins/Temporal/ZonedDateTime/prototype/since/dst-month-day-boundary.js

@@ -0,0 +1,26 @@
+// Copyright (C) 2024 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.zoneddatetime.prototype.since
+description: >
+  Difference with the endpoint being the end of a skipped hour, chooses the
+  smaller of two possible durations
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+// Based on a test case by Adam Shaw
+
+const timeZone = TemporalHelpers.springForwardFallBackTimeZone();
+
+const d1 = new Temporal.ZonedDateTime(957258000_000_000_000n /* = 2000-05-02T02:00-07:00 */, timeZone);
+const d2 = new Temporal.ZonedDateTime(954669600_000_000_000n /* = 2000-04-02T03:00-07:00 */, timeZone);
+// NOTE: nonexistent hour just before d2
+
+const result = d1.since(d2, { largestUnit: "months" });
+
+TemporalHelpers.assertDuration(
+  result, 0, 0, 0, 29, 23, 0, 0, 0, 0, 0,
+  "Result should not balance up to months, but pick the smaller of two possible durations"
+);

test/built-ins/Temporal/ZonedDateTime/prototype/until/dst-month-day-boundary.js

@@ -0,0 +1,26 @@
+// Copyright (C) 2024 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.zoneddatetime.prototype.until
+description: >
+  Difference with the endpoint being the end of a skipped hour, chooses the
+  smaller of two possible durations
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+// Based on a test case by Adam Shaw
+
+const timeZone = TemporalHelpers.springForwardFallBackTimeZone();
+
+const d1 = new Temporal.ZonedDateTime(957258000_000_000_000n /* = 2000-05-02T02:00-07:00 */, timeZone);
+const d2 = new Temporal.ZonedDateTime(954669600_000_000_000n /* = 2000-04-02T03:00-07:00 */, timeZone);
+// NOTE: nonexistent hour just before d2
+
+const result = d1.until(d2, { largestUnit: "months" });
+
+TemporalHelpers.assertDuration(
+  result, 0, 0, 0, -29, -23, 0, 0, 0, 0, 0,
+  "Result should not balance up to months, but pick the smaller of two possible durations"
+);