Temporal: Add more coverage for non-ISO PlainMonthDay underspecification

Built-in non-ISO calendars require either monthCode/day, or month/day plus
some form of year specification.

This adds test coverage for each of the categories listed in
tc39/proposal-temporal#2664, of which some must
currently reside in the test/intl402/ folders.

harness/temporalHelpers.js

@@ -2025,6 +2025,8 @@ var TemporalHelpers = {
     plainMonthDayStringsInvalid() {
       return [
         "11-18junk",
+        "11-18[u-ca=gregory]",
+        "11-18[u-ca=hebrew]",
       ];
     },
 

test/built-ins/Temporal/PlainMonthDay/from/calendar-monthdayfromfields-validates-fields.js

@@ -0,0 +1,31 @@
+// 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.plainmonthday.from
+description: >
+    Calendar.monthDayFromFields method validates which fields must be present
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const calendar = new class extends Temporal.Calendar {
+  fields(fields) {
+    return fields.slice().concat("fnord");
+  }
+  monthDayFromFields(fields) {
+    // accept everything except fnord
+    assert.sameValue(fields.fnord, undefined);
+    return new Temporal.PlainMonthDay(1, 1, this, 1972);
+  }
+}("iso8601");
+
+// This would throw on any non-ISO builtin calendar
+const result = Temporal.PlainMonthDay.from({ month: 8, day: 16, calendar });
+TemporalHelpers.assertPlainMonthDay(result, "M01", 1, "monthDayFromFields determines what fields are necessary")
+
+assert.throws(
+  Test262Error,
+  () => Temporal.PlainMonthDay.from({ monthCode: "M09", day: 19, fnord: "fnord", calendar }),
+  "monthDayFromFields determines what fields are disallowed"
+);

test/built-ins/Temporal/PlainMonthDay/from/fields-object.js

@@ -16,6 +16,10 @@ const tests = [
   [{ month: 10, day: 1, days: 31 }, "option bag with plural 'days'"],
   [new Temporal.PlainMonthDay(10, 1), "PlainMonthDay object"],
   [Temporal.PlainDate.from("2019-10-01"), "PlainDate object"],
+  [{ monthCode: "M10", day: 1, calendar: "iso8601" }, "option bag with monthCode and explicit ISO calendar"],
+  [{ month: 10, day: 1, calendar: "iso8601" }, "option bag with month and explicit ISO calendar"],
+  [{ monthCode: "M10", day: 1, calendar: Temporal.Calendar.from("iso8601") }, "option bag with monthCode and object ISO calendar"],
+  [{ month: 10, day: 1, calendar: Temporal.Calendar.from("iso8601") }, "option bag with month and object ISO calendar"],
 ];
 
 for (const [argument, description = argument] of tests) {

test/intl402/Temporal/Calendar/prototype/monthDayFromFields/fields-underspecified.js

@@ -0,0 +1,20 @@
+// 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: Throw a RangeError if only one of era/eraYear fields is present
+features: [Temporal]
+---*/
+
+const tests = [
+  ["gregory", { year: 2000, month: 5, day: 2, era: "ce" }, "era present but not eraYear"],
+  ["gregory", { year: 2000, month: 5, day: 2, eraYear: 1 }, "eraYear present but not era"],
+  ["gregory", { month: 8, day: 1 }, "no monthCode or year specification, non-ISO Gregorian"],
+  ["hebrew", { month: 8, day: 1 }, "no monthCode or year specification, non-ISO non-Gregorian"],
+];
+
+for (const [calendarId, arg, description] of tests) {
+  const instance = new Temporal.Calendar(calendarId);
+  assert.throws(TypeError, () => instance.monthDayFromFields(arg), description);
+}

test/intl402/Temporal/PlainMonthDay/from/fields-object.js

@@ -0,0 +1,33 @@
+// 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.plainmonthday.from
+description: Basic tests for PlainMonthDay.from(object) with non-ISO calendar
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const okTests = [
+  [{ monthCode: "M08", day: 1, calendar: "gregory" }, "gregory", "monthCode and non-ISO Gregorian string calendar"],
+  [{ monthCode: "M08", day: 1, calendar: "hebrew" }, "hebrew", "monthCode and non-ISO non-Gregorian string calendar"],
+  [{ monthCode: "M08", day: 1, calendar: Temporal.Calendar.from("gregory") }, "gregory", "monthCode and non-ISO Gregorian object calendar"],
+  [{ monthCode: "M08", day: 1, calendar: Temporal.Calendar.from("hebrew") }, "hebrew", "monthCode and non-ISO non-Gregorian object calendar"],
+];
+
+for (const [argument, expectedCalendar, description] of okTests) {
+  const plainMonthDay = Temporal.PlainMonthDay.from(argument);
+  TemporalHelpers.assertPlainMonthDay(plainMonthDay, "M08", 1, description);
+  assert.sameValue(plainMonthDay.calendarId, expectedCalendar, `resulting calendar is ${expectedCalendar}`);
+}
+
+const notOkTests = [
+  [{ month: 8, day: 1, calendar: "gregory" }, "month and non-ISO string calendar"],
+  [{ month: 8, day: 1, calendar: "hebrew" }, "month and non-ISO non-Gregorian string calendar"],
+  [{ month: 8, day: 1, calendar: Temporal.Calendar.from("gregory") }, "month and non-ISO Gregorian object calendar"],
+  [{ month: 8, day: 1, calendar: Temporal.Calendar.from("hebrew") }, "month and non-ISO non-Gregorian object calendar"],
+];
+
+for (const [argument, description] of notOkTests) {
+  assert.throws(TypeError, () => Temporal.PlainMonthDay.from(argument), description);
+}