LibJS: Implement Temporal.TimeZone.from()

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

@@ -25,6 +25,9 @@ void TimeZoneConstructor::initialize(GlobalObject& global_object)
     // 11.3.1 Temporal.TimeZone.prototype, https://tc39.es/proposal-temporal/#sec-temporal-timezone-prototype
     define_direct_property(vm.names.prototype, global_object.temporal_time_zone_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);
 }
 
@@ -79,4 +82,13 @@ Value TimeZoneConstructor::construct(FunctionObject& new_target)
     return create_temporal_time_zone(global_object, canonical, &new_target);
 }
 
+// 11.3.2 Temporal.TimeZone.from ( item )
+JS_DEFINE_NATIVE_FUNCTION(TimeZoneConstructor::from)
+{
+    auto item = vm.argument(0);
+
+    // 1. Return ? ToTemporalTimeZone(item).
+    return to_temporal_time_zone(global_object, item);
+}
+
 }

Userland/Libraries/LibJS/Runtime/Temporal/TimeZoneConstructor.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/TimeZone/TimeZone.from.js

@@ -0,0 +1,15 @@
+describe("normal behavior", () => {
+    test("length is 1", () => {
+        expect(Temporal.TimeZone.from).toHaveLength(1);
+    });
+
+    test("basic functionality", () => {
+        const timeZone = new Temporal.TimeZone("UTC");
+        const timeZoneLike = {};
+        const zonedDateTimeLike = { timeZone: {} };
+        expect(Temporal.TimeZone.from(timeZone)).toBe(timeZone);
+        expect(Temporal.TimeZone.from(timeZoneLike)).toBe(timeZoneLike);
+        expect(Temporal.TimeZone.from(zonedDateTimeLike)).toBe(zonedDateTimeLike.timeZone);
+        // TODO: test from("string") once ParseTemporalTimeZoneString is working
+    });
+});