Temporal: Tests for reference ISO dates

Tests for the process of calculating the reference ISO day for
Temporal.PlainYearMonth and the reference ISO year for
Temporal.PlainMonthDay.

Normative PR: https://github.com/tc39/proposal-temporal/pull/2475

test/built-ins/Temporal/Calendar/prototype/monthDayFromFields/reference-year-1972.js

@@ -20,4 +20,10 @@ let result = cal.monthDayFromFields({ year: 2021, monthCode: "M02", day: 29 });
 TemporalHelpers.assertPlainMonthDay(result, "M02", 29, "year is ignored and reference year should be a leap year if monthCode is given");
 
 result = cal.monthDayFromFields({ year: 2021, month: 2, day: 29 }, { overflow: "constrain" });
-TemporalHelpers.assertPlainMonthDay(result, "M02", 28, "year should not be ignored if monthCode is not given");
+TemporalHelpers.assertPlainMonthDay(result, "M02", 28, "year should not be ignored if monthCode is not given (overflow constrain)");
+
+assert.throws(
+  RangeError,
+  () => cal.monthDayFromFields({ year: 2021, month: 2, day: 29 }, { overflow: "reject" }),
+  "year should not be ignored if monthCode is not given (overflow reject)"
+);

test/built-ins/Temporal/Calendar/prototype/yearMonthFromFields/reference-day.js

@@ -0,0 +1,38 @@
+// 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.calendar.prototype.yearmonthfromfields
+description: Reference ISO day is chosen to be the first of the calendar month
+info: |
+  6.d. Perform ! CreateDataPropertyOrThrow(_fields_, *"day"*, *1*<sub>𝔽</sub>).
+    e. Let _result_ be ? CalendarDateToISO(_calendar_.[[Identifier]], _fields_, _options_).
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const cal = new Temporal.Calendar("iso8601");
+
+const result1 = cal.yearMonthFromFields({ year: 2023, monthCode: "M01", day: 13 });
+TemporalHelpers.assertPlainYearMonth(
+  result1,
+  2023, 1, "M01",
+  "reference day is 1 even if day is given",
+  /* era = */ undefined, /* era year = */ undefined, /* reference day = */ 1
+);
+
+const result2 = cal.yearMonthFromFields({ year: 2021, monthCode: "M02", day: 50 }, { overflow: "constrain" });
+TemporalHelpers.assertPlainYearMonth(
+  result2,
+  2021, 2, "M02",
+  "reference day is 1 even if day is out of range (overflow constrain)",
+  /* era = */ undefined, /* era year = */ undefined, /* reference day = */ 1
+);
+
+const result3 = cal.yearMonthFromFields({ year: 2021, monthCode: "M02", day: 50 }, { overflow: "reject" });
+TemporalHelpers.assertPlainYearMonth(
+  result3,
+  2021, 2, "M02",
+  "reference day is 1 even if day is out of range (overflow reject)",
+  /* era = */ undefined, /* era year = */ undefined, /* reference day = */ 1
+);

test/intl402/Temporal/Calendar/prototype/monthDayFromFields/reference-year-1972.js

@@ -0,0 +1,76 @@
+// 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.calendar.prototype.monthdayfromfields
+description: Deterministic choosing of the reference year
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const gregory = new Temporal.Calendar("gregory");
+
+const result1 = gregory.monthDayFromFields({ year: 2021, monthCode: "M02", day: 29 });
+TemporalHelpers.assertPlainMonthDay(
+  result1, "M02", 29,
+  "year is ignored and reference year should be 1972 if monthCode is given",
+  1972
+);
+
+const result2 = gregory.monthDayFromFields({ year: 2021, month: 2, day: 29 }, { overflow: "constrain" });
+TemporalHelpers.assertPlainMonthDay(
+  result2, "M02", 28,
+  "if monthCode is not given, year is used to determine if calendar date exists, but reference year should still be 1972",
+  1972
+);
+
+assert.throws(
+  RangeError,
+  () => gregory.monthDayFromFields({ year: 2021, month: 2, day: 29 }, { overflow: "reject" }),
+  "RangeError thrown if calendar date does not exist in given year and overflow is reject"
+);
+
+const hebrew = new Temporal.Calendar("hebrew");
+
+const result3 = hebrew.monthDayFromFields({ monthCode: "M01", day: 1 });
+TemporalHelpers.assertPlainMonthDay(
+  result3, "M01", 1,
+  "reference year should be 1972 if date exists in 1972",
+  1972
+);
+
+const result4 = hebrew.monthDayFromFields({ monthCode: "M05L", day: 1 });
+TemporalHelpers.assertPlainMonthDay(
+  result4, "M05L", 1,
+  "reference year should be the latest ISO year before 1972 if date does not exist in 1972",
+  1970
+);
+
+const result5 = hebrew.monthDayFromFields({ year: 5781, monthCode: "M02", day: 30 });
+TemporalHelpers.assertPlainMonthDay(
+  result5, "M02", 30,
+  "year is ignored if monthCode is given (Cheshvan 5781 has 29 days)",
+  1971
+);
+
+const result6 = hebrew.monthDayFromFields({ year: 5781, month: 2, day: 30 }, { overflow: "constrain" });
+TemporalHelpers.assertPlainMonthDay(
+  result6, "M02", 29,
+  "if monthCode is not given, year is used to determine if calendar date exists, but reference year still correct",
+  1972
+);
+
+assert.throws(
+  RangeError,
+  () => hebrew.monthDayFromFields({ year: 5781, month: 2, day: 30 }, { overflow: "reject" }),
+  "RangeError thrown if calendar date does not exist in given year and overflow is reject"
+);
+
+const result7 = hebrew.monthDayFromFields({ monthCode: "M04", day: 26 });
+TemporalHelpers.assertPlainMonthDay(
+  result7, "M04", 26,
+  "reference date should be the later one, if two options exist in ISO year 1972",
+  1972
+);
+assert.sameValue(result7.getISOFields().isoMonth, 12, "reference date should be 1972-12-31");
+assert.sameValue(result7.getISOFields().isoDay, 31, "reference date should be 1972-12-31");

test/intl402/Temporal/Calendar/prototype/yearMonthFromFields/reference-day.js

@@ -0,0 +1,161 @@
+// 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.calendar.prototype.yearmonthfromfields
+description: Reference ISO day is chosen to be the first of the calendar month
+info: |
+  6.d. Perform ! CreateDataPropertyOrThrow(_fields_, *"day"*, *1*<sub>𝔽</sub>).
+    e. Let _result_ be ? CalendarDateToISO(_calendar_.[[Identifier]], _fields_, _options_).
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const gregory = new Temporal.Calendar("gregory");
+
+const result1 = gregory.yearMonthFromFields({ year: 2023, monthCode: "M01", day: 13 });
+TemporalHelpers.assertPlainYearMonth(
+  result1,
+  2023, 1, "M01",
+  "reference day is 1 even if day is given",
+  "ce", 2023, /* reference day = */ 1
+);
+
+const result2 = gregory.yearMonthFromFields({ year: 2021, monthCode: "M02", day: 50 }, { overflow: "constrain" });
+TemporalHelpers.assertPlainYearMonth(
+  result2,
+  2021, 2, "M02",
+  "reference day is set correctly even if day is out of range (overflow constrain)",
+  "ce", 2021, /* reference day = */ 1
+);
+
+const result3 = gregory.yearMonthFromFields({ year: 2021, monthCode: "M02", day: 50 }, { overflow: "reject" });
+TemporalHelpers.assertPlainYearMonth(
+  result3,
+  2021, 2, "M02",
+  "reference day is set correctly even if day is out of range (overflow reject)",
+  "ce", 2021, /* reference day = */ 1
+);
+
+const hebrew = new Temporal.Calendar("hebrew");
+
+const result4 = hebrew.yearMonthFromFields({ year: 5782, monthCode: "M04", day: 20 });
+TemporalHelpers.assertPlainYearMonth(
+  result4,
+  5782, 4, "M04",
+  "reference day is the first of the calendar month even if day is given",
+  /* era = */ undefined, /* era year = */ undefined, /* reference day = */ 5
+);
+const isoFields = result4.getISOFields();
+assert.sameValue(isoFields.isoYear, 2021, "Tevet 5782 begins in ISO year 2021");
+assert.sameValue(isoFields.isoMonth, 12, "Tevet 5782 begins in ISO month 12");
+
+const result5 = hebrew.yearMonthFromFields({ year: 5783, monthCode: "M05L" }, { overflow: "constrain" });
+TemporalHelpers.assertPlainYearMonth(
+  result5,
+  5783, 6, "M06",
+  "month code M05L does not exist in year 5783 (overflow constrain); Hebrew calendar constrains Adar I to Adar",
+  /* era = */ undefined, /* era year = */ undefined, /* reference day = */ 22
+);
+
+assert.throws(
+  RangeError,
+  () => hebrew.yearMonthFromFields({ year: 5783, monthCode: "M05L" }, { overflow: "reject" }),
+  "month code M05L does not exist in year 5783 (overflow reject)",
+);
+
+const result6 = hebrew.yearMonthFromFields({ year: 5783, month: 13 }, { overflow: "constrain" });
+TemporalHelpers.assertPlainYearMonth(
+  result6,
+  5783, 12, "M12",
+  "month 13 does not exist in year 5783 (overflow constrain)",
+  /* era = */ undefined, /* era year = */ undefined, /* reference day = */ 18
+);
+
+assert.throws(
+  RangeError,
+  () => hebrew.yearMonthFromFields({ year: 5783, month: 13 }, { overflow: "reject" }),
+  "month 13 does not exist in year 5783 (overflow reject)",
+);
+
+const result7 = hebrew.yearMonthFromFields({ year: 5782, monthCode: "M04", day: 50 }, { overflow: "constrain" });
+TemporalHelpers.assertPlainYearMonth(
+  result7,
+  5782, 4, "M04",
+  "reference day is set correctly even if day is out of range (overflow constrain)",
+  /* era = */ undefined, /* era year = */ undefined, /* reference day = */ 5
+);
+
+const result8 = hebrew.yearMonthFromFields({ year: 5782, monthCode: "M04", day: 50 }, { overflow: "reject" });
+TemporalHelpers.assertPlainYearMonth(
+  result8,
+  5782, 4, "M04",
+  "reference day is set correctly even if day is out of range (overflow reject)",
+  /* era = */ undefined, /* era year = */ undefined, /* reference day = */ 5
+);
+
+const chinese = new Temporal.Calendar("chinese");
+
+// Month codes, month indices, and the ISO reference days of the months in 2022
+const months2022TestData = [
+  // TODO: Sources conflict over whether M01L and M12L exist in _any_ year.
+  // Clarify this, and delete if appropriate. ICU has them, but may be wrong.
+  ["M01", 1, 1],
+  ["M02", 2, 3],
+  ["M03", 3, 1],
+  ["M04", 4, 1],
+  ["M05", 5, 30],
+  ["M06", 6, 29],
+  ["M07", 7, 29],
+  ["M08", 8, 27],
+  ["M09", 9, 26],
+  ["M10", 10, 25],
+  ["M11", 11, 24],
+  ["M12", 12, 23],
+];
+for (const [nonLeapMonthCode, month, referenceISODay] of months2022TestData) {
+  const leapMonthCode = nonLeapMonthCode + "L";
+  const fields = { year: 2022, monthCode: leapMonthCode };
+
+  const result = chinese.yearMonthFromFields(fields, { overflow: "constrain" });
+  TemporalHelpers.assertPlainYearMonth(
+    result,
+    2022, month, nonLeapMonthCode,
+    `Chinese intercalary month ${leapMonthCode} does not exist in year 2022 (overflow constrain)`,
+    /* era = */ undefined, /* era year = */ undefined, referenceISODay
+  );
+
+  assert.throws(
+    RangeError,
+    () => chinese.yearMonthFromFields(fields, { overflow: "reject" }),
+    `Chinese intercalary month ${leapMonthCode} does not exist in year 2022 (overflow reject)`
+  );
+}
+
+// Years in which leap months exist according to ICU
+const leapMonthsTestData = [
+  ["M01L", 2148, 2, 20],
+  ["M02L", 2023, 3, 22],
+  ["M03L", 1993, 4, 22],
+  ["M04L", 2020, 5, 23],
+  ["M05L", 2009, 6, 23],
+  ["M06L", 2017, 7, 23],
+  ["M07L", 2006, 8, 24],
+  ["M08L", 1995, 9, 25],
+  ["M09L", 2014, 10, 24],
+  ["M10L", 1984, 11, 23],
+  ["M11L", 2033, 12, 22],
+  ["M12L", 1889, 13, 21, 1890, 1],
+];
+for (const [monthCode, year, month, referenceISODay, isoYear = year, isoMonth = month] of leapMonthsTestData) {
+  const result = chinese.yearMonthFromFields({ year, monthCode });
+  TemporalHelpers.assertPlainYearMonth(
+    result,
+    year, month, monthCode,
+    `Date of sample Chinese intercalary month ${monthCode}`,
+    /* era = */ undefined, /* era year = */ undefined, referenceISODay
+  );
+  const isoFields = result.getISOFields();
+  assert.sameValue(isoFields.isoYear, isoYear, `${year}-${monthCode} starts in ISO year ${isoYear}`);
+  assert.sameValue(isoFields.isoMonth, isoMonth, `${year}-${monthCode} starts in ISO month ${isoMonth}`);
+}

test/staging/Intl402/Temporal/old/hebrew-leap-months.js

@@ -58,22 +58,3 @@ for (var i = 1; i <= 12; i++) {
     calendar: "hebrew"
   }));
 }
-
-// Leap month in non-leap year (reject): Adar I 5780
-assert.throws(RangeError, () => Temporal.PlainDate.from({
-  year: 5780,
-  monthCode: "M05L",
-  day: 1,
-  calendar: "hebrew"
-}, { overflow: "reject" }));
-
-// Leap month in non-leap year (constrain): 15 Adar I 5780 => 30 Av 5780
-var date = Temporal.PlainDate.from({
-  year: 5780,
-  monthCode: "M05L",
-  day: 15,
-  calendar: "hebrew"
-});
-assert.sameValue(date.month, 5);
-assert.sameValue(date.monthCode, "M05");
-assert.sameValue(date.day, 30);