Temporal: Tests for dates out-of-range when finding end of month

In PlainYearMonth arithmetic, we need to find the end of the month when
adding a negative duration or subtracting a positive one. This end of the
month can be out of range.

Test case based on one provided by Anba. See issue:
tc39/proposal-temporal#2700

Author: ptomato

Diff for: test/built-ins/Temporal/PlainYearMonth/prototype/add/end-of-month-out-of-range.js

@@ -0,0 +1,30 @@
+// 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.add
+description: RangeError thrown when adding negative duration and end of month is out of range
+features: [Temporal]
+info: |
+  AddDurationToOrSubtractDurationFromPlainYearMonth:
+  12. If _sign_ < 0, then
+    a. Let _oneMonthDuration_ be ! CreateTemporalDuration(0, 1, 0, 0, 0, 0, 0, 0, 0, 0).
+    b. Let _nextMonth_ be ? CalendarDateAdd(_calendar_, _intermediateDate_, _oneMonthDuration_, *undefined*, _dateAdd_).
+    c. Let _endOfMonthISO_ be ! AddISODate(_nextMonth_.[[ISOYear]], _nextMonth_.[[ISOMonth]], _nextMonth_.[[ISODay]], 0, 0, 0, -1, *"constrain"*).
+    d. Let _endOfMonth_ be ? CreateTemporalDate(_endOfMonthISO_.[[Year]], _endOfMonthISO_.[[Month]], _endOfMonthISO_.[[Day]], _calendar_).
+---*/
+
+// Based on a test case by André Bargull <[email protected]>
+
+const duration = new Temporal.Duration(0, 0, 0, -1);
+
+// Calendar addition result is out of range
+assert.throws(RangeError, () => new Temporal.PlainYearMonth(275760, 9).add(duration), "Addition of 1 month to receiver out of range");
+
+// Calendar addition succeeds, but subtracting 1 day gives out of range result
+const cal = new class extends Temporal.Calendar {
+  dateAdd() {
+    return new Temporal.PlainDate(-271821, 4, 19);
+  }
+}("iso8601");
+assert.throws(RangeError, () => new Temporal.PlainYearMonth(2000, 1, cal).add(duration), "Subtraction of 1 day from next month out of range");

Diff for: test/built-ins/Temporal/PlainYearMonth/prototype/subtract/end-of-month-out-of-range.js

@@ -0,0 +1,30 @@
+// 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.subtract
+description: RangeError thrown when subtracting positive duration and end of month is out of range
+features: [Temporal]
+info: |
+  AddDurationToOrSubtractDurationFromPlainYearMonth:
+  12. If _sign_ < 0, then
+    a. Let _oneMonthDuration_ be ! CreateTemporalDuration(0, 1, 0, 0, 0, 0, 0, 0, 0, 0).
+    b. Let _nextMonth_ be ? CalendarDateAdd(_calendar_, _intermediateDate_, _oneMonthDuration_, *undefined*, _dateAdd_).
+    c. Let _endOfMonthISO_ be ! AddISODate(_nextMonth_.[[ISOYear]], _nextMonth_.[[ISOMonth]], _nextMonth_.[[ISODay]], 0, 0, 0, -1, *"constrain"*).
+    d. Let _endOfMonth_ be ? CreateTemporalDate(_endOfMonthISO_.[[Year]], _endOfMonthISO_.[[Month]], _endOfMonthISO_.[[Day]], _calendar_).
+---*/
+
+// Based on a test case by André Bargull <[email protected]>
+
+const duration = new Temporal.Duration(0, 0, 0, 1);
+
+// Calendar addition result is out of range
+assert.throws(RangeError, () => new Temporal.PlainYearMonth(275760, 9).subtract(duration), "Addition of 1 month to receiver out of range");
+
+// Calendar addition succeeds, but subtracting 1 day gives out of range result
+const cal = new class extends Temporal.Calendar {
+  dateAdd() {
+    return new Temporal.PlainDate(-271821, 4, 19);
+  }
+}("iso8601");
+assert.throws(RangeError, () => new Temporal.PlainYearMonth(2000, 1, cal).subtract(duration), "Subtraction of 1 day from next month out of range");