Intl Era Monthcode: Tests for constraining leap day in Indian calendar

Adds tests for constraining 31 Chaitra to 30 Chaitra when moving from a
leap year to a common year, by the add(), subtract(), or with() methods.

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

@@ -0,0 +1,45 @@
+// 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 various basic calculations involving leap years (indian calendar)
+features: [Temporal, Intl.Era-monthcode]
+includes: [temporalHelpers.js]
+---*/
+
+const calendar = "indian";
+const options = { overflow: "reject" };
+
+const leapDay = Temporal.PlainDate.from({ year: 1946, monthCode: "M01", day: 31, calendar }, options);
+
+const years1 = new Temporal.Duration(1);
+const years1n = new Temporal.Duration(-1);
+const years4 = new Temporal.Duration(4);
+const years4n = new Temporal.Duration(-4);
+
+TemporalHelpers.assertPlainDate(
+  leapDay.add(years1),
+  1947, 1, "M01", 30, "Adding 1 year to leap day constrains to 30 Chaitra",
+  "shaka", 1947);
+assert.throws(RangeError, function () {
+  leapDay.add(years1, options);
+}, "Adding 1 year to leap day rejects");
+
+TemporalHelpers.assertPlainDate(
+  leapDay.add(years1n),
+  1945, 1, "M01", 30, "Subtracting 1 year from leap day constrains to 30 Chaitra",
+  "shaka", 1945);
+assert.throws(RangeError, function () {
+  leapDay.add(years1n, options);
+}, "Subtracting 1 year from leap day rejects");
+
+TemporalHelpers.assertPlainDate(
+  leapDay.add(years4, options),
+  1950, 1, "M01", 31, "Adding 4 years to leap day goes to the next leap day",
+  "shaka", 1950);
+
+TemporalHelpers.assertPlainDate(
+  leapDay.add(years4n, options),
+  1942, 1, "M01", 31, "Subtracting 4 years from leap day goes to the previous leap day",
+  "shaka", 1942);

test/intl402/Temporal/PlainDate/prototype/subtract/leap-year-indian.js

@@ -0,0 +1,45 @@
+// 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.subtract
+description: Check various basic calculations involving leap years (indian calendar)
+features: [Temporal, Intl.Era-monthcode]
+includes: [temporalHelpers.js]
+---*/
+
+const calendar = "indian";
+const options = { overflow: "reject" };
+
+const leapDay = Temporal.PlainDate.from({ year: 1946, monthCode: "M01", day: 31, calendar }, options);
+
+const years1 = new Temporal.Duration(-1);
+const years1n = new Temporal.Duration(1);
+const years4 = new Temporal.Duration(-4);
+const years4n = new Temporal.Duration(4);
+
+TemporalHelpers.assertPlainDate(
+  leapDay.subtract(years1),
+  1947, 1, "M01", 30, "Adding 1 year to leap day constrains to 30 Chaitra",
+  "shaka", 1947);
+assert.throws(RangeError, function () {
+  leapDay.subtract(years1, options);
+}, "Adding 1 year to leap day rejects");
+
+TemporalHelpers.assertPlainDate(
+  leapDay.subtract(years1n),
+  1945, 1, "M01", 30, "Subtracting 1 year from leap day constrains to 30 Chaitra",
+  "shaka", 1945);
+assert.throws(RangeError, function () {
+  leapDay.subtract(years1n, options);
+}, "Subtracting 1 year from leap day rejects");
+
+TemporalHelpers.assertPlainDate(
+  leapDay.subtract(years4, options),
+  1950, 1, "M01", 31, "Adding 4 years to leap day goes to the next leap day",
+  "shaka", 1950);
+
+TemporalHelpers.assertPlainDate(
+  leapDay.subtract(years4n, options),
+  1942, 1, "M01", 31, "Subtracting 4 years from leap day goes to the previous leap day",
+  "shaka", 1942);

test/intl402/Temporal/PlainDate/prototype/with/leap-year-indian.js

@@ -0,0 +1,27 @@
+// 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.with
+description: Check various basic calculations involving leap years (indian calendar)
+features: [Temporal, Intl.Era-monthcode]
+includes: [temporalHelpers.js]
+---*/
+
+const calendar = "indian";
+const options = { overflow: "reject" };
+
+const leapDay = Temporal.PlainDate.from({ year: 1946, monthCode: "M01", day: 31, calendar }, options);
+
+TemporalHelpers.assertPlainDate(
+  leapDay.with({ year: 1947 }),
+  1947, 1, "M01", 30, "Changing year to a common year on leap day constrains to 30 Chaitra",
+  "shaka", 1947);
+assert.throws(RangeError, function () {
+  leapDay.with({ year: 1947 }, options);
+}, "Changing year to a common year on leap day rejects");
+
+TemporalHelpers.assertPlainDate(
+  leapDay.with({ year: 1942 }, options),
+  1942, 1, "M01", 31, "Changing year to another leap year on leap day does not reject",
+  "shaka", 1942);

test/intl402/Temporal/PlainDateTime/prototype/add/leap-year-indian.js

@@ -0,0 +1,45 @@
+// 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.plaindatetime.prototype.add
+description: Check various basic calculations involving leap years (indian calendar)
+features: [Temporal, Intl.Era-monthcode]
+includes: [temporalHelpers.js]
+---*/
+
+const calendar = "indian";
+const options = { overflow: "reject" };
+
+const leapDay = Temporal.PlainDateTime.from({ year: 1946, monthCode: "M01", day: 31, hour: 12, minute: 34, calendar }, options);
+
+const years1 = new Temporal.Duration(1);
+const years1n = new Temporal.Duration(-1);
+const years4 = new Temporal.Duration(4);
+const years4n = new Temporal.Duration(-4);
+
+TemporalHelpers.assertPlainDateTime(
+  leapDay.add(years1),
+  1947, 1, "M01", 30, 12, 34, 0, 0, 0, 0, "Adding 1 year to leap day constrains to 30 Chaitra",
+  "shaka", 1947);
+assert.throws(RangeError, function () {
+  leapDay.add(years1, options);
+}, "Adding 1 year to leap day rejects");
+
+TemporalHelpers.assertPlainDateTime(
+  leapDay.add(years1n),
+  1945, 1, "M01", 30, 12, 34, 0, 0, 0, 0, "Subtracting 1 year from leap day constrains to 30 Chaitra",
+  "shaka", 1945);
+assert.throws(RangeError, function () {
+  leapDay.add(years1n, options);
+}, "Subtracting 1 year from leap day rejects");
+
+TemporalHelpers.assertPlainDateTime(
+  leapDay.add(years4, options),
+  1950, 1, "M01", 31, 12, 34, 0, 0, 0, 0, "Adding 4 years to leap day goes to the next leap day",
+  "shaka", 1950);
+
+TemporalHelpers.assertPlainDateTime(
+  leapDay.add(years4n, options),
+  1942, 1, "M01", 31, 12, 34, 0, 0, 0, 0, "Subtracting 4 years from leap day goes to the previous leap day",
+  "shaka", 1942);

test/intl402/Temporal/PlainDateTime/prototype/subtract/leap-year-indian.js

@@ -0,0 +1,45 @@
+// 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.plaindatetime.prototype.subtract
+description: Check various basic calculations involving leap years (indian calendar)
+features: [Temporal, Intl.Era-monthcode]
+includes: [temporalHelpers.js]
+---*/
+
+const calendar = "indian";
+const options = { overflow: "reject" };
+
+const leapDay = Temporal.PlainDateTime.from({ year: 1946, monthCode: "M01", day: 31, hour: 12, minute: 34, calendar }, options);
+
+const years1 = new Temporal.Duration(-1);
+const years1n = new Temporal.Duration(1);
+const years4 = new Temporal.Duration(-4);
+const years4n = new Temporal.Duration(4);
+
+TemporalHelpers.assertPlainDateTime(
+  leapDay.subtract(years1),
+  1947, 1, "M01", 30, 12, 34, 0, 0, 0, 0, "Adding 1 year to leap day constrains to 30 Chaitra",
+  "shaka", 1947);
+assert.throws(RangeError, function () {
+  leapDay.subtract(years1, options);
+}, "Adding 1 year to leap day rejects");
+
+TemporalHelpers.assertPlainDateTime(
+  leapDay.subtract(years1n),
+  1945, 1, "M01", 30, 12, 34, 0, 0, 0, 0, "Subtracting 1 year from leap day constrains to 30 Chaitra",
+  "shaka", 1945);
+assert.throws(RangeError, function () {
+  leapDay.subtract(years1n, options);
+}, "Subtracting 1 year from leap day rejects");
+
+TemporalHelpers.assertPlainDateTime(
+  leapDay.subtract(years4, options),
+  1950, 1, "M01", 31, 12, 34, 0, 0, 0, 0, "Adding 4 years to leap day goes to the next leap day",
+  "shaka", 1950);
+
+TemporalHelpers.assertPlainDateTime(
+  leapDay.subtract(years4n, options),
+  1942, 1, "M01", 31, 12, 34, 0, 0, 0, 0, "Subtracting 4 years from leap day goes to the previous leap day",
+  "shaka", 1942);

test/intl402/Temporal/PlainDateTime/prototype/with/leap-year-indian.js

@@ -0,0 +1,27 @@
+// 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.plaindatetime.prototype.with
+description: Check various basic calculations involving leap years (indian calendar)
+features: [Temporal, Intl.Era-monthcode]
+includes: [temporalHelpers.js]
+---*/
+
+const calendar = "indian";
+const options = { overflow: "reject" };
+
+const leapDay = Temporal.PlainDateTime.from({ year: 1946, monthCode: "M01", day: 31, hour: 12, minute: 34, calendar }, options);
+
+TemporalHelpers.assertPlainDateTime(
+  leapDay.with({ year: 1947 }),
+  1947, 1, "M01", 30, 12, 34, 0, 0, 0, 0, "Changing year to a common year on leap day constrains to 30 Chaitra",
+  "shaka", 1947);
+assert.throws(RangeError, function () {
+  leapDay.with({ year: 1947 }, options);
+}, "Changing year to a common year on leap day rejects");
+
+TemporalHelpers.assertPlainDateTime(
+  leapDay.with({ year: 1942 }, options),
+  1942, 1, "M01", 31, 12, 34, 0, 0, 0, 0, "Changing year to another leap year on leap day does not reject",
+  "shaka", 1942);

test/intl402/Temporal/ZonedDateTime/prototype/add/leap-year-indian.js

@@ -0,0 +1,45 @@
+// 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.zoneddatetime.prototype.add
+description: Check various basic calculations involving leap years (indian calendar)
+features: [Temporal, Intl.Era-monthcode]
+includes: [temporalHelpers.js]
+---*/
+
+const calendar = "indian";
+const options = { overflow: "reject" };
+
+const leapDay = Temporal.ZonedDateTime.from({ year: 1946, monthCode: "M01", day: 31, hour: 12, minute: 34, timeZone: "UTC", calendar }, options);
+
+const years1 = new Temporal.Duration(1);
+const years1n = new Temporal.Duration(-1);
+const years4 = new Temporal.Duration(4);
+const years4n = new Temporal.Duration(-4);
+
+TemporalHelpers.assertPlainDateTime(
+  leapDay.add(years1).toPlainDateTime(),
+  1947, 1, "M01", 30, 12, 34, 0, 0, 0, 0, "Adding 1 year to leap day constrains to 30 Chaitra",
+  "shaka", 1947);
+assert.throws(RangeError, function () {
+  leapDay.add(years1, options);
+}, "Adding 1 year to leap day rejects");
+
+TemporalHelpers.assertPlainDateTime(
+  leapDay.add(years1n).toPlainDateTime(),
+  1945, 1, "M01", 30, 12, 34, 0, 0, 0, 0, "Subtracting 1 year from leap day constrains to 30 Chaitra",
+  "shaka", 1945);
+assert.throws(RangeError, function () {
+  leapDay.add(years1n, options);
+}, "Subtracting 1 year from leap day rejects");
+
+TemporalHelpers.assertPlainDateTime(
+  leapDay.add(years4, options).toPlainDateTime(),
+  1950, 1, "M01", 31, 12, 34, 0, 0, 0, 0, "Adding 4 years to leap day goes to the next leap day",
+  "shaka", 1950);
+
+TemporalHelpers.assertPlainDateTime(
+  leapDay.add(years4n, options).toPlainDateTime(),
+  1942, 1, "M01", 31, 12, 34, 0, 0, 0, 0, "Subtracting 4 years from leap day goes to the previous leap day",
+  "shaka", 1942);

test/intl402/Temporal/ZonedDateTime/prototype/subtract/leap-year-indian.js

@@ -0,0 +1,45 @@
+// 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.zoneddatetime.prototype.subtract
+description: Check various basic calculations involving leap years (indian calendar)
+features: [Temporal, Intl.Era-monthcode]
+includes: [temporalHelpers.js]
+---*/
+
+const calendar = "indian";
+const options = { overflow: "reject" };
+
+const leapDay = Temporal.ZonedDateTime.from({ year: 1946, monthCode: "M01", day: 31, hour: 12, minute: 34, timeZone: "UTC", calendar }, options);
+
+const years1 = new Temporal.Duration(-1);
+const years1n = new Temporal.Duration(1);
+const years4 = new Temporal.Duration(-4);
+const years4n = new Temporal.Duration(4);
+
+TemporalHelpers.assertPlainDateTime(
+  leapDay.subtract(years1).toPlainDateTime(),
+  1947, 1, "M01", 30, 12, 34, 0, 0, 0, 0, "Adding 1 year to leap day constrains to 30 Chaitra",
+  "shaka", 1947);
+assert.throws(RangeError, function () {
+  leapDay.subtract(years1, options);
+}, "Adding 1 year to leap day rejects");
+
+TemporalHelpers.assertPlainDateTime(
+  leapDay.subtract(years1n).toPlainDateTime(),
+  1945, 1, "M01", 30, 12, 34, 0, 0, 0, 0, "Subtracting 1 year from leap day constrains to 30 Chaitra",
+  "shaka", 1945);
+assert.throws(RangeError, function () {
+  leapDay.subtract(years1n, options);
+}, "Subtracting 1 year from leap day rejects");
+
+TemporalHelpers.assertPlainDateTime(
+  leapDay.subtract(years4, options).toPlainDateTime(),
+  1950, 1, "M01", 31, 12, 34, 0, 0, 0, 0, "Adding 4 years to leap day goes to the next leap day",
+  "shaka", 1950);
+
+TemporalHelpers.assertPlainDateTime(
+  leapDay.subtract(years4n, options).toPlainDateTime(),
+  1942, 1, "M01", 31, 12, 34, 0, 0, 0, 0, "Subtracting 4 years from leap day goes to the previous leap day",
+  "shaka", 1942);

test/intl402/Temporal/ZonedDateTime/prototype/with/leap-year-indian.js

@@ -0,0 +1,27 @@
+// 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.zoneddatetime.prototype.with
+description: Check various basic calculations involving leap years (indian calendar)
+features: [Temporal, Intl.Era-monthcode]
+includes: [temporalHelpers.js]
+---*/
+
+const calendar = "indian";
+const options = { overflow: "reject" };
+
+const leapDay = Temporal.ZonedDateTime.from({ year: 1946, monthCode: "M01", day: 31, hour: 12, minute: 34, timeZone: "UTC", calendar }, options);
+
+TemporalHelpers.assertPlainDateTime(
+  leapDay.with({ year: 1947 }).toPlainDateTime(),
+  1947, 1, "M01", 30, 12, 34, 0, 0, 0, 0, "Changing year to a common year on leap day constrains to 30 Chaitra",
+  "shaka", 1947);
+assert.throws(RangeError, function () {
+  leapDay.with({ year: 1947 }, options);
+}, "Changing year to a common year on leap day rejects");
+
+TemporalHelpers.assertPlainDateTime(
+  leapDay.with({ year: 1942 }, options).toPlainDateTime(),
+  1942, 1, "M01", 31, 12, 34, 0, 0, 0, 0, "Changing year to another leap year on leap day does not reject",
+  "shaka", 1942);