serenity/Libraries/LibJS/Tests/builtins/Object/Object.defineProperty.js

describe("normal functionality", () => {
    test("non-configurable property", () => {
        let o = {};
        Object.defineProperty(o, "foo", { value: 1, writable: false, enumerable: false });

        expect(o.foo).toBe(1);
        o.foo = 2;
        expect(o.foo).toBe(1);

        expect(o).not.toHaveConfigurableProperty("foo");
        expect(o).not.toHaveEnumerableProperty("foo");
        expect(o).not.toHaveWritableProperty("foo");
        expect(o).toHaveValueProperty("foo", 1);
    });

    test("array index getter", () => {
        let o = {};
        Object.defineProperty(o, 2, { get() { return 10; } });
        expect(o[2]).toBe(10);
    });

    test("configurable property", () => {
        let o = {};
        Object.defineProperty(o, "foo", { value: "hi", writable: true, enumerable: true });

        expect(o.foo).toBe("hi");
        o.foo = "ho";
        expect(o.foo).toBe("ho");

        expect(o).not.toHaveConfigurableProperty("foo");
        expect(o).toHaveEnumerableProperty("foo");
        expect(o).toHaveWritableProperty("foo");
        expect(o).toHaveValueProperty("foo", "ho");
    });

    test("reconfigure configurable property", () => {
        let o = {};
        Object.defineProperty(o, "foo", { value: 9, configurable: true, writable: false });
        Object.defineProperty(o, "foo", { configurable: true, writable: true });

        expect(o).toHaveConfigurableProperty("foo");
        expect(o).toHaveWritableProperty("foo");
        expect(o).not.toHaveEnumerableProperty("foo");
        expect(o).toHaveValueProperty("foo", 9);
    });

    test("define accessor", () => {
        let o = {};

        Object.defineProperty(o, "foo", {
            configurable: true,
            get() {
                return o.secret_foo + 1;
            },
            set(value) {
                this.secret_foo = value + 1;
            },
        });

        o.foo = 10;
        expect(o.foo).toBe(12);
        o.foo = 20;
        expect(o.foo).toBe(22);

        Object.defineProperty(o, "foo", { configurable: true, value: 4 });

        expect(o.foo).toBe(4);
        expect(o.foo = 5).toBe(5);
        expect(o.foo = 4).toBe(4);
    });
});

describe("errors", () => {
    test("redefine non-configurable property", () => {
        let o = {};
        Object.defineProperty(o, "foo", { value: 1, writable: true, enumerable: true });

        expect(() => {
            Object.defineProperty(o, "foo", { value: 2, writable: false, enumerable: true });
        }).toThrowWithMessage(TypeError, "Cannot change attributes of non-configurable property 'foo'");
    });

    test("cannot define 'value' and 'get' in the same descriptor", () => {
        let o = {};

        expect(() => {
            Object.defineProperty(o, "a", {
                get() {},
                value: 9,
            });
        }).toThrowWithMessage(TypeError, "Accessor property descriptor cannot specify a value or writable key");
    });

    test("cannot define 'value' and 'set' in the same descriptor", () => {
        let o = {};

        expect(() => {
            Object.defineProperty(o, "a", {
                set() {},
                writable: true,
            });
        }).toThrowWithMessage(TypeError, "Accessor property descriptor cannot specify a value or writable key");
    });

    test("redefine non-configurable accessor", () => {
        let o = {};

        Object.defineProperty(o, "foo", {
            configurable: false,
            get() {
                return this.secret_foo + 2;
            },
            set(value) {
                o.secret_foo = value + 2;
            },
        });

        expect(() => {
            Object.defineProperty(o, "foo", {
                configurable: false,
                get() {
                    return this.secret_foo + 2;
                },
            });
        }).toThrowWithMessage(TypeError, "Cannot change attributes of non-configurable property 'foo'");
    });
});