Add PlainMonthDay month code tests for non-ISO calendars

test/intl402/Temporal/PlainMonthDay/from/buddhist-invalid-month-code-m13.js

@@ -0,0 +1,26 @@
+// 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.plainmonthday.from
+description: M13 month code is invalid for Buddhist calendar (12-month calendar)
+features: [Temporal, Intl.Era-monthcode]
+---*/
+
+// The Buddhist calendar is a 12-month calendar and should not accept M13
+
+const calendar = "buddhist";
+
+assert.throws(RangeError, () => {
+  Temporal.PlainMonthDay.from({ calendar, monthCode: "M13", day: 1 });
+}, `M13 should not be a valid month code for ${calendar} calendar`);
+
+// M13 should throw even with overflow: "constrain"
+assert.throws(RangeError, () => {
+  Temporal.PlainMonthDay.from({ calendar, monthCode: "M13", day: 1 }, { overflow: "constrain" });
+}, `M13 should not be valid for ${calendar} calendar even with constrain overflow`);
+
+// M13 should throw with overflow: "reject"
+assert.throws(RangeError, () => {
+  Temporal.PlainMonthDay.from({ calendar, monthCode: "M13", day: 1 }, { overflow: "reject" });
+}, `M13 should not be valid for ${calendar} calendar with reject overflow`);

test/intl402/Temporal/PlainMonthDay/from/buddhist-month-codes.js

@@ -0,0 +1,36 @@
+// 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.plainmonthday.from
+description: PlainMonthDay can be created for all month codes (M01-M12) in Buddhist calendar
+features: [Temporal, Intl.Era-monthcode]
+includes: [temporalHelpers.js]
+---*/
+
+// Test that all month codes M01-M12 are valid for the Buddhist calendar
+// The Buddhist calendar follows the Gregorian calendar structure
+
+const calendar = "buddhist";
+
+for (const { monthCode, daysInMonth } of TemporalHelpers.ISOMonths) {
+  // Test creation with monthCode and day 1
+  const pmd = Temporal.PlainMonthDay.from({ calendar, monthCode, day: 1 });
+  TemporalHelpers.assertPlainMonthDay(pmd, monthCode, 1, `monthCode ${monthCode} should be preserved`);
+
+  // Test with maximum day value for this month (minimum for PlainMonthDay)
+  const pmdMax = Temporal.PlainMonthDay.from({ calendar, monthCode, day: daysInMonth });
+  TemporalHelpers.assertPlainMonthDay(pmdMax, monthCode, daysInMonth, `${monthCode} with day ${daysInMonth} should be valid`);
+
+  // Test constrain overflow
+  const constrained = Temporal.PlainMonthDay.from(
+    { calendar, monthCode, day: daysInMonth + 1 },
+    { overflow: "constrain" }
+  );
+  TemporalHelpers.assertPlainMonthDay(constrained, monthCode, daysInMonth, `day ${daysInMonth + 1} should be constrained to ${daysInMonth} for ${monthCode}`);
+
+  // Test reject overflow
+  assert.throws(RangeError, () => {
+    Temporal.PlainMonthDay.from({ calendar, monthCode, day: daysInMonth + 1 }, { overflow: "reject" });
+  }, `${monthCode} with day ${daysInMonth + 1} should throw with reject overflow`);
+}

test/intl402/Temporal/PlainMonthDay/from/chinese-invalid-month-code-m13.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.plainmonthday.from
+description: M13 month code is invalid for Chinese calendar (12-month calendar with leap months)
+features: [Temporal, Intl.Era-monthcode]
+---*/
+
+// The Chinese calendar is a 12-month lunisolar calendar with leap months (M01L-M12L)
+// but does not have a thirteenth month (M13)
+
+const calendar = "chinese";
+
+assert.throws(RangeError, () => {
+  Temporal.PlainMonthDay.from({ calendar, monthCode: "M13", day: 1 });
+}, `M13 should not be a valid month code for ${calendar} calendar`);
+
+// M13 should throw even with overflow: "constrain"
+assert.throws(RangeError, () => {
+  Temporal.PlainMonthDay.from({ calendar, monthCode: "M13", day: 1 }, { overflow: "constrain" });
+}, `M13 should not be valid for ${calendar} calendar even with constrain overflow`);
+
+// M13 should throw with overflow: "reject"
+assert.throws(RangeError, () => {
+  Temporal.PlainMonthDay.from({ calendar, monthCode: "M13", day: 1 }, { overflow: "reject" });
+}, `M13 should not be valid for ${calendar} calendar with reject overflow`);

test/intl402/Temporal/PlainMonthDay/from/chinese-leap-month-codes-common.js

@@ -0,0 +1,53 @@
+// 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.plainmonthday.from
+description: PlainMonthDay can be created for common leap month codes in Chinese calendar
+features: [Temporal, Intl.Era-monthcode]
+---*/
+
+// Test common leap months in the Chinese calendar
+// The Chinese calendar is a lunisolar calendar where leap months are inserted
+// to keep the lunar year synchronized with the solar year.
+// Common leap months (occurring more frequently in the astronomical cycle):
+// M02L, M03L, M04L, M05L, M06L, M07L, M08L
+//
+// The distribution of leap months follows astronomical calculations.
+//
+// Note: M01L, M02L and M08L through M12L are temporarily omitted from this
+// test because while any leap month can have 30 days, there isn't a year in the
+// supported range where these months do, and it's not yet well-defined what
+// reference ISO year should be used.
+// See https://github.com/tc39/proposal-intl-era-monthcode/issues/60
+
+const calendar = "chinese";
+
+// Test leap months M03L-M07L with day 30
+// These are well-established leap months that can have 30 days
+const leapMonthsWith30Days = ["M03L", "M04L", "M05L", "M06L", "M07L"];
+
+for (const monthCode of leapMonthsWith30Days) {
+  // Test creation with monthCode
+  const pmd = Temporal.PlainMonthDay.from({ calendar, monthCode, day: 1 });
+  assert.sameValue(pmd.monthCode, monthCode, `leap monthCode ${monthCode} should be preserved`);
+  assert.sameValue(pmd.day, 1, `day should be 1 for ${monthCode}`);
+
+  // These leap months can have up to 30 days (minimum for PlainMonthDay)
+  const pmd30 = Temporal.PlainMonthDay.from({ calendar, monthCode, day: 30 });
+  assert.sameValue(pmd30.monthCode, monthCode, `${monthCode} with day 30 should be valid`);
+  assert.sameValue(pmd30.day, 30, `day should be 30 for ${monthCode}`);
+
+  // Test constrain overflow - day 31 should be constrained to 30
+  const constrained = Temporal.PlainMonthDay.from(
+    { calendar, monthCode, day: 31 },
+    { overflow: "constrain" }
+  );
+  assert.sameValue(constrained.monthCode, monthCode, `${monthCode} should be preserved with constrain`);
+  assert.sameValue(constrained.day, 30, `day 31 should be constrained to 30 for ${monthCode}`);
+
+  // Test reject overflow - day 31 should throw
+  assert.throws(RangeError, () => {
+    Temporal.PlainMonthDay.from({ calendar, monthCode, day: 31 }, { overflow: "reject" });
+  }, `${monthCode} with day 31 should throw with reject overflow`);
+}

test/intl402/Temporal/PlainMonthDay/from/chinese-month-codes.js

@@ -0,0 +1,43 @@
+// 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.plainmonthday.from
+description: PlainMonthDay can be created for all regular month codes (M01-M12) in Chinese calendar
+features: [Temporal, Intl.Era-monthcode]
+---*/
+
+// Test that all regular month codes M01-M12 are valid for the Chinese calendar
+// The Chinese calendar is a lunisolar calendar, so months vary in length
+// Leap months (M01L-M12L) are tested elsewhere
+
+const calendar = "chinese";
+const monthCodes = [
+  "M01", "M02", "M03", "M04", "M05", "M06",
+  "M07", "M08", "M09", "M10", "M11", "M12"
+];
+
+for (const monthCode of monthCodes) {
+  // Test creation with monthCode
+  const pmd = Temporal.PlainMonthDay.from({ calendar, monthCode, day: 1 });
+  assert.sameValue(pmd.monthCode, monthCode, `monthCode ${monthCode} should be preserved`);
+  assert.sameValue(pmd.day, 1, "day should be 1");
+
+  // Test with day 30 (months can have 29 or 30 days)
+  const pmd30 = Temporal.PlainMonthDay.from({ calendar, monthCode, day: 30 });
+  assert.sameValue(pmd30.monthCode, monthCode, `${monthCode} with day 30 should be valid`);
+  assert.sameValue(pmd30.day, 30, `day should be 30 for ${monthCode}`);
+
+  // Test constrain overflow - Chinese months vary from 29-30 days
+  const constrained = Temporal.PlainMonthDay.from(
+    { calendar, monthCode, day: 31 },
+    { overflow: "constrain" }
+  );
+  assert.sameValue(constrained.monthCode, monthCode, `${monthCode} should be preserved with constrain`);
+  assert.sameValue(constrained.day, 30, `day 31 should be constrained to 30 for ${monthCode}`);
+
+  // Test reject overflow for day 31
+  assert.throws(RangeError, () => {
+    Temporal.PlainMonthDay.from({ calendar, monthCode, day: 31 }, { overflow: "reject" });
+  }, `${monthCode} with day 31 should throw with reject overflow`);
+}

test/intl402/Temporal/PlainMonthDay/from/coptic-invalid-month-code-m14.js

@@ -0,0 +1,26 @@
+// 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.plainmonthday.from
+description: M14 month code is invalid for Coptic calendar (13-month calendar)
+features: [Temporal, Intl.Era-monthcode]
+---*/
+
+// The Coptic calendar has 13 months (M01-M13) and should not accept M14
+
+const calendar = "coptic";
+
+assert.throws(RangeError, () => {
+  Temporal.PlainMonthDay.from({ calendar, monthCode: "M14", day: 1 });
+}, `M14 should not be a valid month code for ${calendar} calendar`);
+
+// M14 should throw even with overflow: "constrain"
+assert.throws(RangeError, () => {
+  Temporal.PlainMonthDay.from({ calendar, monthCode: "M14", day: 1 }, { overflow: "constrain" });
+}, `M14 should not be valid for ${calendar} calendar even with constrain overflow`);
+
+// M14 should throw with overflow: "reject"
+assert.throws(RangeError, () => {
+  Temporal.PlainMonthDay.from({ calendar, monthCode: "M14", day: 1 }, { overflow: "reject" });
+}, `M14 should not be valid for ${calendar} calendar with reject overflow`);

test/intl402/Temporal/PlainMonthDay/from/coptic-month-codes.js

@@ -0,0 +1,65 @@
+// 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.plainmonthday.from
+description: PlainMonthDay can be created for all month codes (M01-M13) in Coptic calendar
+features: [Temporal, Intl.Era-monthcode]
+---*/
+
+// Test that all month codes M01-M13 are valid for the Coptic calendar
+// The Coptic calendar has 12 months of 30 days each, plus a 13th month (Epagomenal days)
+// of 5 or 6 days
+
+const calendar = "coptic";
+
+// M01-M12: Regular months with 30 days each
+const regularMonthCodes = [
+  "M01", "M02", "M03", "M04", "M05", "M06",
+  "M07", "M08", "M09", "M10", "M11", "M12"
+];
+
+for (const monthCode of regularMonthCodes) {
+  // Test creation with monthCode
+  const pmd = Temporal.PlainMonthDay.from({ calendar, monthCode, day: 1 });
+  assert.sameValue(pmd.monthCode, monthCode, `monthCode ${monthCode} should be preserved`);
+  assert.sameValue(pmd.day, 1, "day should be 1");
+
+  // Test with day 30 (all regular months have 30 days)
+  const pmd30 = Temporal.PlainMonthDay.from({ calendar, monthCode, day: 30 });
+  assert.sameValue(pmd30.monthCode, monthCode, `${monthCode} with day 30 should be valid`);
+  assert.sameValue(pmd30.day, 30, `day should be 30 for ${monthCode}`);
+
+  // Test overflow: constrain to 30
+  const constrained = Temporal.PlainMonthDay.from(
+    { calendar, monthCode, day: 31 },
+    { overflow: "constrain" }
+  );
+  assert.sameValue(constrained.monthCode, monthCode, `${monthCode} should be preserved with constrain`);
+  assert.sameValue(constrained.day, 30, `day 31 should be constrained to 30 for ${monthCode}`);
+
+  // Test overflow: reject should throw for day 31
+  assert.throws(RangeError, () => {
+    Temporal.PlainMonthDay.from({ calendar, monthCode, day: 31 }, { overflow: "reject" });
+  }, `${monthCode} with day 31 should throw with reject overflow`);
+}
+
+// M13: Short month (Epagomenal days) with 5 or 6 days
+
+// Test M13 with day 6 (maximum, valid in leap years)
+const pmdM13Day6 = Temporal.PlainMonthDay.from({ calendar, monthCode: "M13", day: 6 });
+assert.sameValue(pmdM13Day6.monthCode, "M13", "M13 should be valid with day 6");
+assert.sameValue(pmdM13Day6.day, 6, "day should be 6 for M13");
+
+// Test M13 overflow: constrain to maximum
+const constrained = Temporal.PlainMonthDay.from(
+  { calendar, monthCode: "M13", day: 7 },
+  { overflow: "constrain" }
+);
+assert.sameValue(constrained.monthCode, "M13", "M13 should be preserved with constrain");
+assert.sameValue(constrained.day, 6, "day 7 should be constrained to 6 for M13");
+
+// Test M13 overflow: reject should throw for day 7
+assert.throws(RangeError, () => {
+  Temporal.PlainMonthDay.from({ calendar, monthCode: "M13", day: 7 }, { overflow: "reject" });
+}, "M13 with day 7 should throw with reject overflow");

test/intl402/Temporal/PlainMonthDay/from/dangi-invalid-month-code-m13.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.plainmonthday.from
+description: M13 month code is invalid for Dangi calendar (12-month calendar with leap months)
+features: [Temporal, Intl.Era-monthcode]
+---*/
+
+// The Dangi calendar is a 12-month lunisolar calendar with leap months (M01L-M12L)
+// but does not have a thirteenth month (M13)
+
+const calendar = "dangi";
+
+assert.throws(RangeError, () => {
+  Temporal.PlainMonthDay.from({ calendar, monthCode: "M13", day: 1 });
+}, `M13 should not be a valid month code for ${calendar} calendar`);
+
+// M13 should throw even with overflow: "constrain"
+assert.throws(RangeError, () => {
+  Temporal.PlainMonthDay.from({ calendar, monthCode: "M13", day: 1 }, { overflow: "constrain" });
+}, `M13 should not be valid for ${calendar} calendar even with constrain overflow`);
+
+// M13 should throw with overflow: "reject"
+assert.throws(RangeError, () => {
+  Temporal.PlainMonthDay.from({ calendar, monthCode: "M13", day: 1 }, { overflow: "reject" });
+}, `M13 should not be valid for ${calendar} calendar with reject overflow`);

test/intl402/Temporal/PlainMonthDay/from/dangi-leap-month-codes-common.js

@@ -0,0 +1,54 @@
+// 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.plainmonthday.from
+description: PlainMonthDay can be created for common leap month codes in Dangi calendar
+features: [Temporal, Intl.Era-monthcode]
+---*/
+
+// Test common leap months in the Dangi calendar
+// Dangi is a lunisolar calendar where leap months follow the same distribution as Chinese
+// Common leap months (occurring more frequently in the astronomical cycle):
+// M02L, M03L, M04L, M05L, M06L, M07L, M08L
+//
+// Like the Chinese calendar, the Dangi calendar inserts leap months to keep the
+// lunar year synchronized with the solar year. The distribution of leap months
+// follows astronomical calculations.
+//
+// Note: M01L, M02L and M08L through M12L are temporarily omitted from this
+// test because while any leap month can have 30 days, there isn't a year in the
+// supported range where these months do, and it's not yet well-defined what
+// reference ISO year should be used.
+// See https://github.com/tc39/proposal-intl-era-monthcode/issues/60
+
+const calendar = "dangi";
+
+// Test leap months M03L-M07L with day 30
+// These are well-established leap months that can have 30 days
+const leapMonthsWith30Days = ["M03L", "M04L", "M05L", "M06L", "M07L"];
+
+for (const monthCode of leapMonthsWith30Days) {
+  // Test creation with monthCode
+  const pmd = Temporal.PlainMonthDay.from({ calendar, monthCode, day: 1 });
+  assert.sameValue(pmd.monthCode, monthCode, `leap monthCode ${monthCode} should be preserved`);
+  assert.sameValue(pmd.day, 1, `day should be 1 for ${monthCode}`);
+
+  // These leap months can have up to 30 days (minimum for PlainMonthDay)
+  const pmd30 = Temporal.PlainMonthDay.from({ calendar, monthCode, day: 30 });
+  assert.sameValue(pmd30.monthCode, monthCode, `${monthCode} with day 30 should be valid`);
+  assert.sameValue(pmd30.day, 30, `day should be 30 for ${monthCode}`);
+
+  // Test constrain overflow - day 31 should be constrained to 30
+  const constrained = Temporal.PlainMonthDay.from(
+    { calendar, monthCode, day: 31 },
+    { overflow: "constrain" }
+  );
+  assert.sameValue(constrained.monthCode, monthCode, `${monthCode} should be preserved with constrain`);
+  assert.sameValue(constrained.day, 30, `day 31 should be constrained to 30 for ${monthCode}`);
+
+  // Test reject overflow - day 31 should throw
+  assert.throws(RangeError, () => {
+    Temporal.PlainMonthDay.from({ calendar, monthCode, day: 31 }, { overflow: "reject" });
+  }, `${monthCode} with day 31 should throw with reject overflow`);
+}