Intl Era Monthcode: Constrain tests for Hebrew calendar

test/intl402/Temporal/PlainDate/prototype/add/leap-year-hebrew.js

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+// Copyright (C) 2025 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaindate.prototype.add
+description: Check constraining days due to leap years (hebrew calendar)
+includes: [temporalHelpers.js]
+features: [Temporal, Intl.Era-monthcode]
+---*/
+
+// Adar I (M05L) has 30 days, and in common years will be constrained to Adar
+// (M06) which has 29 days.
+// See also leap-months-hebrew.js and constrain-day-hebrew.js.
+
+const calendar = "hebrew";
+const options = { overflow: "reject" };
+
+const years1 = new Temporal.Duration(1);
+const years1n = new Temporal.Duration(-1);
+
+const adarI = Temporal.PlainDate.from({ year: 5782, monthCode: "M05L", day: 30, calendar }, options);
+
+TemporalHelpers.assertPlainDate(
+  adarI.add(years1),
+  5783, 6, "M06", 29, "Adding 1 year to 30 Adar I constrains to 29 Adar",
+  "am", 5783);
+assert.throws(RangeError, function () {
+  adarI.add(years1, options);
+}, "Adding 1 year to 30 Adar I rejects (either because the month or day would be constrained)");
+
+TemporalHelpers.assertPlainDate(
+  adarI.add(years1n),
+  5781, 6, "M06", 29, "Subtracting 1 year from 30 Adar I constrains to 29 Adar",
+  "am", 5781);
+assert.throws(RangeError, function () {
+  adarI.add(years1n, options);
+}, "Subtracting 1 year from 30 Adar I rejects (either because the month or day would be constrained)");