Add tests for adding negative durations to/subtracting durations from…

… the last representable year/month of the ISO calendar

See tc39/proposal-temporal#3029

test/built-ins/Temporal/PlainYearMonth/prototype/add/subtract-from-last-representable-month.js

@@ -0,0 +1,21 @@
+// 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.plainyearmonth.prototype.add
+description: RangeError thrown when adding negative duration to last representable month.
+features: [Temporal]
+---*/
+
+const lastMonth = new Temporal.PlainYearMonth(275760, 9);
+
+// See https://tc39.es/proposal-temporal/#sec-temporal-adddurationtoyearmonth
+// (step 10d)
+assert.throws(RangeError, () => lastMonth.add({seconds: -1}));
+assert.throws(RangeError, () => lastMonth.add({minutes: -1}));
+assert.throws(RangeError, () => lastMonth.add({hours: -1}));
+assert.throws(RangeError, () => lastMonth.add({days: -1}));
+assert.throws(RangeError, () => lastMonth.add({weeks: -1}));
+assert.throws(RangeError, () => lastMonth.add({months: -1}));
+assert.throws(RangeError, () => lastMonth.add({years: -1}));
+

test/built-ins/Temporal/PlainYearMonth/prototype/subtract/subtract-from-last-representable-month.js

@@ -0,0 +1,21 @@
+// 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.plainyearmonth.prototype.subtract
+description: RangeError thrown when subtracting duration from last representable month.
+features: [Temporal]
+---*/
+
+const lastMonth = new Temporal.PlainYearMonth(275760, 9);
+
+// See https://tc39.es/proposal-temporal/#sec-temporal-adddurationtoyearmonth
+// (step 10d)
+assert.throws(RangeError, () => lastMonth.subtract({seconds: 1}));
+assert.throws(RangeError, () => lastMonth.subtract({minutes: 1}));
+assert.throws(RangeError, () => lastMonth.subtract({hours: 1}));
+assert.throws(RangeError, () => lastMonth.subtract({days: 1}));
+assert.throws(RangeError, () => lastMonth.subtract({weeks: 1}));
+assert.throws(RangeError, () => lastMonth.subtract({months: 1}));
+assert.throws(RangeError, () => lastMonth.subtract({years: 1}));
+