LibJS: Implement Temporal.PlainMonthDay.prototype.with()

Userland/Libraries/LibJS/Runtime/Temporal/PlainMonthDayPrototype.cpp

@@ -33,6 +33,7 @@ void PlainMonthDayPrototype::initialize(GlobalObject& global_object)
     define_native_accessor(vm.names.day, day_getter, {}, Attribute::Configurable);
 
     u8 attr = Attribute::Writable | Attribute::Configurable;
+    define_native_function(vm.names.with, with, 1, attr);
     define_native_function(vm.names.equals, equals, 1, attr);
     define_native_function(vm.names.toString, to_string, 0, attr);
     define_native_function(vm.names.toLocaleString, to_locale_string, 0, attr);
@@ -81,6 +82,49 @@ JS_DEFINE_NATIVE_FUNCTION(PlainMonthDayPrototype::day_getter)
     return Value(TRY(calendar_day(global_object, calendar, *month_day)));
 }
 
+// 10.3.6 Temporal.PlainMonthDay.prototype.with ( temporalMonthDayLike [ , options ] ), https://tc39.es/proposal-temporal/#sec-temporal.plainmonthday.prototype.with
+JS_DEFINE_NATIVE_FUNCTION(PlainMonthDayPrototype::with)
+{
+    auto temporal_month_day_like = vm.argument(0);
+
+    // 1. Let monthDay be the this value.
+    // 2. Perform ? RequireInternalSlot(monthDay, [[InitializedTemporalMonthDay]]).
+    auto* month_day = TRY(typed_this_object(global_object));
+
+    // 3. If Type(temporalMonthDayLike) is not Object, then
+    if (!temporal_month_day_like.is_object()) {
+        // a. Throw a TypeError exception.
+        return vm.throw_completion<TypeError>(global_object, ErrorType::NotAnObject, temporal_month_day_like.to_string_without_side_effects());
+    }
+
+    // 4. Perform ? RejectObjectWithCalendarOrTimeZone(temporalMonthDayLike).
+    TRY(reject_object_with_calendar_or_time_zone(global_object, temporal_month_day_like.as_object()));
+
+    // 5. Let calendar be monthDay.[[Calendar]].
+    auto& calendar = month_day->calendar();
+
+    // 6. Let fieldNames be ? CalendarFields(calendar, « "day", "month", "monthCode", "year" »).
+    auto field_names = TRY(calendar_fields(global_object, calendar, { "day"sv, "month"sv, "monthCode"sv, "year"sv }));
+
+    // 7. Let partialMonthDay be ? PreparePartialTemporalFields(temporalMonthDayLike, fieldNames).
+    auto* partial_month_day = TRY(prepare_partial_temporal_fields(global_object, temporal_month_day_like.as_object(), field_names));
+
+    // 8. Set options to ? GetOptionsObject(options).
+    auto* options = TRY(get_options_object(global_object, vm.argument(1)));
+
+    // 9. Let fields be ? PrepareTemporalFields(monthDay, fieldNames, «»).
+    auto* fields = TRY(prepare_temporal_fields(global_object, *month_day, field_names, {}));
+
+    // 10. Set fields to ? CalendarMergeFields(calendar, fields, partialMonthDay).
+    fields = TRY(calendar_merge_fields(global_object, calendar, *fields, *partial_month_day));
+
+    // 11. Set fields to ? PrepareTemporalFields(fields, fieldNames, «»).
+    fields = TRY(prepare_temporal_fields(global_object, *fields, field_names, {}));
+
+    // 12. Return ? MonthDayFromFields(calendar, fields, options).
+    return TRY(month_day_from_fields(global_object, calendar, *fields, options));
+}
+
 // 10.3.7 Temporal.PlainMonthDay.prototype.equals ( other ), https://tc39.es/proposal-temporal/#sec-temporal.plainmonthday.prototype.equals
 JS_DEFINE_NATIVE_FUNCTION(PlainMonthDayPrototype::equals)
 {

Userland/Libraries/LibJS/Runtime/Temporal/PlainMonthDayPrototype.h

@@ -23,6 +23,7 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(calendar_getter);
     JS_DECLARE_NATIVE_FUNCTION(month_code_getter);
     JS_DECLARE_NATIVE_FUNCTION(day_getter);
+    JS_DECLARE_NATIVE_FUNCTION(with);
     JS_DECLARE_NATIVE_FUNCTION(equals);
     JS_DECLARE_NATIVE_FUNCTION(to_string);
     JS_DECLARE_NATIVE_FUNCTION(to_locale_string);

Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainMonthDay/PlainMonthDay.prototype.with.js

@@ -0,0 +1,69 @@
+describe("correct behavior", () => {
+    test("length is 1", () => {
+        expect(Temporal.PlainMonthDay.prototype.with).toHaveLength(1);
+    });
+
+    test("basic functionality", () => {
+        const plainMonthDay = new Temporal.PlainMonthDay(1, 1);
+        const values = [
+            [{ monthCode: "M07" }, new Temporal.PlainMonthDay(7, 1)],
+            [{ monthCode: "M07", day: 6 }, new Temporal.PlainMonthDay(7, 6)],
+            [{ year: 0, month: 7, day: 6 }, new Temporal.PlainMonthDay(7, 6)],
+        ];
+        for (const [arg, expected] of values) {
+            expect(plainMonthDay.with(arg).equals(expected)).toBeTrue();
+        }
+
+        // Supplying the same values doesn't change the month/day, but still creates a new object
+        const plainMonthDayLike = {
+            month: plainMonthDay.month,
+            day: plainMonthDay.day,
+        };
+        expect(plainMonthDay.with(plainMonthDayLike)).not.toBe(plainMonthDay);
+        expect(plainMonthDay.with(plainMonthDayLike).equals(plainMonthDay)).toBeTrue();
+    });
+});
+
+describe("errors", () => {
+    test("this value must be a Temporal.PlainMonthDay object", () => {
+        expect(() => {
+            Temporal.PlainMonthDay.prototype.with.call("foo");
+        }).toThrowWithMessage(TypeError, "Not an object of type Temporal.PlainMonthDay");
+    });
+
+    test("argument must be an object", () => {
+        expect(() => {
+            new Temporal.PlainMonthDay(1, 1).with("foo");
+        }).toThrowWithMessage(TypeError, "foo is not an object");
+        expect(() => {
+            new Temporal.PlainMonthDay(1, 1).with(42);
+        }).toThrowWithMessage(TypeError, "42 is not an object");
+    });
+
+    test("argument must have one of 'day', 'month', 'monthCode', 'year'", () => {
+        expect(() => {
+            new Temporal.PlainMonthDay(1, 1).with({});
+        }).toThrowWithMessage(
+            TypeError,
+            "Object must have at least one of the following properties: day, month, monthCode, year"
+        );
+    });
+
+    test("argument must not have 'calendar' or 'timeZone'", () => {
+        expect(() => {
+            new Temporal.PlainMonthDay(1, 1).with({ calendar: {} });
+        }).toThrowWithMessage(TypeError, "Object must not have a defined calendar property");
+        expect(() => {
+            new Temporal.PlainMonthDay(1, 1).with({ timeZone: {} });
+        }).toThrowWithMessage(TypeError, "Object must not have a defined timeZone property");
+    });
+
+    test("month property only works in combination with year", () => {
+        expect(() => {
+            new Temporal.PlainMonthDay(1, 1).with({ month: 1 });
+        }).toThrowWithMessage(
+            TypeError,
+            "Required property monthCode or year is missing or undefined"
+        );
+    });
+});