LibJS: Move tests to /Tests/LibJS

Author: https://github.com/gmta
Commit: https://github.com/LadybirdBrowser/ladybird/commit/e3faa9b5add
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/7572
Reviewed-by: https://github.com/trflynn89 ✅

Tests/LibJS/Runtime/builtins/Object/Object.preventExtensions.js

@@ -0,0 +1,67 @@
+describe("correct behavior", () => {
+    test("non-object arguments", () => {
+        expect(Object.preventExtensions()).toBeUndefined();
+        expect(Object.preventExtensions(undefined)).toBeUndefined();
+        expect(Object.preventExtensions(null)).toBeNull();
+        expect(Object.preventExtensions(true)).toBeTrue();
+        expect(Object.preventExtensions(6)).toBe(6);
+        expect(Object.preventExtensions("test")).toBe("test");
+
+        let s = Symbol();
+        expect(Object.preventExtensions(s)).toBe(s);
+    });
+
+    test("basic functionality", () => {
+        let o = { foo: "foo" };
+        expect(o.foo).toBe("foo");
+        o.bar = "bar";
+        expect(o.bar).toBe("bar");
+
+        expect(Object.preventExtensions(o)).toBe(o);
+        expect(o.foo).toBe("foo");
+        expect(o.bar).toBe("bar");
+
+        o.baz = "baz";
+        expect(o.baz).toBeUndefined();
+    });
+
+    test("modifying existing properties", () => {
+        const o = { foo: "bar" };
+        Object.preventExtensions(o);
+        o.foo = "baz";
+        expect(o.foo).toBe("baz");
+    });
+
+    test("deleting existing properties", () => {
+        const o = { foo: "bar" };
+        Object.preventExtensions(o);
+        delete o.foo;
+        expect(o).not.toHaveProperty("foo");
+    });
+});
+
+describe("errors", () => {
+    test("defining a property on a non-extensible object", () => {
+        let o = {};
+        Object.preventExtensions(o);
+
+        expect(() => {
+            Object.defineProperty(o, "baz", { value: "baz" });
+        }).toThrowWithMessage(TypeError, "Object's [[DefineOwnProperty]] method returned false");
+
+        expect(o.baz).toBeUndefined();
+    });
+
+    test("putting property on a non-extensible object", () => {
+        let o = {};
+        Object.preventExtensions(o);
+
+        expect(() => {
+            "use strict";
+            o.foo = "foo";
+        }).toThrowWithMessage(TypeError, "Cannot set property 'foo' of [object Object]");
+
+        expect((o.foo = "foo")).toBe("foo");
+        expect(o.foo).toBeUndefined();
+    });
+});