LibJS: Implement Temporal.PlainMonthDay.from

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

@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/TypeCasts.h>
 #include <LibJS/Runtime/GlobalObject.h>
 #include <LibJS/Runtime/Temporal/AbstractOperations.h>
 #include <LibJS/Runtime/Temporal/Calendar.h>
@@ -28,6 +29,9 @@ void PlainMonthDayConstructor::initialize(GlobalObject& global_object)
     define_direct_property(vm.names.prototype, global_object.temporal_plain_month_day_prototype(), 0);
 
     define_direct_property(vm.names.length, Value(2), Attribute::Configurable);
+
+    u8 attr = Attribute::Writable | Attribute::Configurable;
+    define_native_function(vm.names.from, from, 1, attr);
 }
 
 // 10.1.1 Temporal.PlainMonthDay ( isoMonth, isoDay [ , calendarLike [ , referenceISOYear ] ] ), https://tc39.es/proposal-temporal/#sec-temporal.plainmonthday
@@ -89,4 +93,31 @@ Value PlainMonthDayConstructor::construct(FunctionObject& new_target)
     return create_temporal_month_day(global_object, m, d, *calendar, ref, &new_target);
 }
 
+// 10.2.2 Temporal.PlainMonthDay.from ( item [ , options ] ), https://tc39.es/proposal-temporal/#sec-temporal.plainmonthday.from
+JS_DEFINE_NATIVE_FUNCTION(PlainMonthDayConstructor::from)
+{
+    // 1. Set options to ? GetOptionsObject(options).
+    auto* options = get_options_object(global_object, vm.argument(1));
+    if (vm.exception())
+        return {};
+
+    auto item = vm.argument(0);
+
+    // 2. If Type(item) is Object and item has an [[InitializedTemporalMonthDay]] internal slot, then
+    if (item.is_object() && is<PlainMonthDay>(item.as_object())) {
+        // a. Perform ? ToTemporalOverflow(options).
+        (void)to_temporal_overflow(global_object, *options);
+        if (vm.exception())
+            return {};
+
+        auto& plain_month_day_object = static_cast<PlainMonthDay&>(item.as_object());
+
+        // b. Return ? CreateTemporalMonthDay(item.[[ISOMonth]], item.[[ISODay]], item.[[Calendar]], item.[[ISOYear]]).
+        return create_temporal_month_day(global_object, plain_month_day_object.iso_month(), plain_month_day_object.iso_day(), plain_month_day_object.calendar(), plain_month_day_object.iso_year());
+    }
+
+    // 3. Return ? ToTemporalMonthDay(item, options).
+    return to_temporal_month_day(global_object, item, options);
+}
+
 }

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

@@ -23,6 +23,8 @@ public:
 
 private:
     virtual bool has_constructor() const override { return true; }
+
+    JS_DECLARE_NATIVE_FUNCTION(from);
 };
 
 }

Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainMonthDay/PlainMonthDay.from.js

@@ -0,0 +1,58 @@
+describe("correct behavior", () => {
+    test("length is 1", () => {
+        expect(Temporal.PlainMonthDay.from).toHaveLength(1);
+    });
+
+    test("PlainDate instance argument", () => {
+        const plainDate = new Temporal.PlainDate(2021, 7, 6);
+        const plainMonthDay = Temporal.PlainMonthDay.from(plainDate);
+        expect(plainMonthDay.monthCode).toBe("M07");
+        expect(plainMonthDay.day).toBe(6);
+    });
+
+    test("PlainMonthDay instance argument", () => {
+        const plainMonthDay_ = new Temporal.PlainMonthDay(7, 6);
+        const plainMonthDay = Temporal.PlainMonthDay.from(plainMonthDay_);
+        expect(plainMonthDay.monthCode).toBe("M07");
+        expect(plainMonthDay.day).toBe(6);
+    });
+
+    test("ZonedDateTime instance argument", () => {
+        const timeZone = new Temporal.TimeZone("UTC");
+        const zonedDateTime = new Temporal.ZonedDateTime(1625614921000000000n, timeZone);
+        const plainMonthDay = Temporal.PlainMonthDay.from(zonedDateTime);
+        expect(plainMonthDay.monthCode).toBe("M07");
+        expect(plainMonthDay.day).toBe(6);
+    });
+
+    test("fields object argument", () => {
+        const object = {
+            month: 7,
+            day: 6,
+        };
+        const plainMonthDay = Temporal.PlainMonthDay.from(object);
+        expect(plainMonthDay.monthCode).toBe("M07");
+        expect(plainMonthDay.day).toBe(6);
+    });
+
+    // Un-skip once ParseISODateTime, ToTemporalMonthDay & ParseTemporalMonthDayString are fully implemented
+    test.skip("PlainMonthDay string argument", () => {
+        const plainMonthDay = Temporal.PlainMonthDay.from("2021-07-06T23:42:01Z");
+        expect(plainMonthDay.monthCode).toBe("M07");
+        expect(plainMonthDay.day).toBe(6);
+    });
+});
+
+describe("errors", () => {
+    test("missing fields", () => {
+        expect(() => {
+            Temporal.PlainMonthDay.from({});
+        }).toThrowWithMessage(TypeError, "Required property month is missing or undefined");
+        expect(() => {
+            Temporal.PlainMonthDay.from({ month: 1 });
+        }).toThrowWithMessage(TypeError, "Required property day is missing or undefined");
+        expect(() => {
+            Temporal.PlainMonthDay.from({ day: 1 });
+        }).toThrowWithMessage(TypeError, "Required property month is missing or undefined");
+    });
+});