LibJS: Implement Temporal.Calendar.from()

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

@@ -25,6 +25,9 @@ void CalendarConstructor::initialize(GlobalObject& global_object)
     // 12.3.1 Temporal.Calendar.prototype, https://tc39.es/proposal-temporal/#sec-temporal-calendar-prototype
     define_direct_property(vm.names.prototype, global_object.temporal_calendar_prototype(), 0);
 
+    u8 attr = Attribute::Writable | Attribute::Configurable;
+    define_native_function(vm.names.from, from, 1, attr);
+
     define_direct_property(vm.names.length, Value(1), Attribute::Configurable);
 }
 
@@ -61,4 +64,13 @@ Value CalendarConstructor::construct(FunctionObject& new_target)
     return create_temporal_calendar(global_object, identifier, &new_target);
 }
 
+// 12.3.2 Temporal.Calendar.from ( item ), https://tc39.es/proposal-temporal/#sec-temporal.calendar.from
+JS_DEFINE_NATIVE_FUNCTION(CalendarConstructor::from)
+{
+    auto item = vm.argument(0);
+
+    // 1. Return ? ToTemporalCalendar(item).
+    return to_temporal_calendar(global_object, item);
+}
+
 }

Userland/Libraries/LibJS/Runtime/Temporal/CalendarConstructor.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/Calendar/Calendar.from.js

@@ -0,0 +1,21 @@
+describe("normal behavior", () => {
+    test("length is 1", () => {
+        expect(Temporal.Calendar.from).toHaveLength(1);
+    });
+
+    test("basic functionality", () => {
+        const plainDate = new Temporal.PlainDate(1970, 1, 1);
+        const plainTime = new Temporal.PlainTime();
+        const plainDateTime = new Temporal.PlainDateTime(1970, 1, 1);
+        // TODO: PlainMonthDay, PlainYearMonth, ZonedDateTime
+        const calendarLike = {};
+        const withCalendarLike = { calendar: {} };
+        expect(Temporal.Calendar.from(plainDate)).toBe(plainDate.calendar);
+        expect(Temporal.Calendar.from(plainTime)).toBe(plainTime.calendar);
+        expect(Temporal.Calendar.from(plainDateTime)).toBe(plainDateTime.calendar);
+        expect(Temporal.Calendar.from(calendarLike)).toBe(calendarLike);
+        expect(Temporal.Calendar.from(withCalendarLike)).toBe(withCalendarLike.calendar);
+        expect(Temporal.Calendar.from("iso8601").id).toBe("iso8601");
+        // TODO: test Temporal.Calendar.from("TemporalCalendarString") once ParseTemporalCalendarString is working
+    });
+});