LibJS/Tests: Add tests for Temporal.TimeZone() constructor

Userland/Libraries/LibJS/Tests/builtins/Temporal/TimeZone/TimeZone.js

@@ -0,0 +1,35 @@
+describe("errors", () => {
+    test("called without new", () => {
+        expect(() => {
+            Temporal.TimeZone();
+        }).toThrowWithMessage(TypeError, "Temporal.TimeZone constructor must be called with 'new'");
+    });
+
+    test("Invalid time zone name", () => {
+        expect(() => {
+            new Temporal.TimeZone("foo");
+        }).toThrowWithMessage(RangeError, "Invalid time zone name");
+    });
+});
+
+describe("normal behavior", () => {
+    test("length is 1", () => {
+        expect(Temporal.TimeZone).toHaveLength(1);
+    });
+
+    test("basic functionality", () => {
+        const timeZone = new Temporal.TimeZone("UTC");
+        expect(timeZone.id).toBe("UTC");
+        expect(typeof timeZone).toBe("object");
+        expect(timeZone).toBeInstanceOf(Temporal.TimeZone);
+        expect(Object.getPrototypeOf(timeZone)).toBe(Temporal.TimeZone.prototype);
+    });
+
+    test("canonicalizes time zone name", () => {
+        expect(new Temporal.TimeZone("Utc").id).toBe("UTC");
+        expect(new Temporal.TimeZone("utc").id).toBe("UTC");
+        expect(new Temporal.TimeZone("uTC").id).toBe("UTC");
+    });
+
+    // TODO: Add tests for time numeric zone offset once that's implemented
+});