LibJS: Implement Temporal.ZonedDateTime.prototype.withTimeZone

Userland/Libraries/LibJS/Tests/builtins/Temporal/ZonedDateTime/ZonedDateTime.prototype.withTimeZone.js

@@ -0,0 +1,44 @@
+describe("correct behavior", () => {
+    test("length is 1", () => {
+        expect(Temporal.ZonedDateTime.prototype.withTimeZone).toHaveLength(1);
+    });
+
+    test("basic functionality", () => {
+        const object = {};
+        const zonedDateTime = new Temporal.ZonedDateTime(1n, object);
+        expect(zonedDateTime.timeZone).toBe(object);
+
+        const timeZone = new Temporal.TimeZone("UTC");
+        const withTimeZoneZonedDateTime = zonedDateTime.withTimeZone(timeZone);
+        expect(withTimeZoneZonedDateTime.timeZone).toBe(timeZone);
+    });
+
+    // FIXME: Enable this when time zone string parsing is implemented.
+    test.skip("from time zone string", () => {
+        const object = {};
+        const zonedDateTime = new Temporal.ZonedDateTime(1n, object);
+        expect(zonedDateTime.timeZone).toBe(object);
+
+        const withTimeZoneZonedDateTime = zonedDateTime.withTimeZone("UTC");
+        expect(withTimeZoneZonedDateTime.timeZone).toBeInstanceOf(Temporal.TimeZone);
+        expect(withTimeZoneZonedDateTime.timeZone.id).toBe("UTC");
+    });
+});
+
+describe("errors", () => {
+    test("this value must be a Temporal.ZonedDateTime object", () => {
+        expect(() => {
+            Temporal.ZonedDateTime.prototype.withTimeZone.call("foo");
+        }).toThrowWithMessage(TypeError, "Not an object of type Temporal.ZonedDateTime");
+    });
+
+    // FIXME: Enable this when time zone string parsing is implemented.
+    test.skip("from invalid time zone string", () => {
+        const zonedDateTime = new Temporal.ZonedDateTime(1n, {});
+
+        // FIXME: Use "toThrowWithMessage" once this has an error message.
+        expect(() => {
+            zonedDateTime.withTimeZone("UTCfoobar");
+        }).toThrow(RangeError);
+    });
+});