ladybird/Tests/LibJS/Runtime/destructuring-assignment-with-expression-defaults.js

test("class expression as default value in array destructuring", () => {
    var x;
    [x = class {}] = [undefined];
    expect(typeof x).toBe("function");
});

test("class expression as default value in object destructuring", () => {
    var x;
    ({ x = class {} } = {});
    expect(typeof x).toBe("function");
});

test("class expression as default value in for-of array destructuring", () => {
    for (var [x = class C {}] of [[undefined]]) {
        expect(typeof x).toBe("function");
    }
});

test("function expression as default value in array destructuring", () => {
    var x;
    [x = function () {}] = [undefined];
    expect(typeof x).toBe("function");
});

test("nested function as default value in array destructuring", () => {
    var x;
    [
        x = function () {
            return function inner() {};
        },
    ] = [undefined];
    expect(typeof x).toBe("function");
    expect(typeof x()).toBe("function");
});

test("MemberExpression target in array destructuring", () => {
    var obj = {};
    [obj.x] = [42];
    expect(obj.x).toBe(42);
});

test("MemberExpression target with object literal in array destructuring", () => {
    var setValue;
    [
        {
            set y(val) {
                setValue = val;
            },
        }.y,
    ] = [23];
    expect(setValue).toBe(23);
});

test("MemberExpression target with object literal in object destructuring", () => {
    var setValue;
    ({
        x: {
            set y(val) {
                setValue = val;
            },
        }.y,
    } = { x: 42 });
    expect(setValue).toBe(42);
});

test("object destructuring evaluates MemberExpression target before source property", () => {
    var log = [];
    var source = {
        get p() {
            log.push("get p");
            return 42;
        },
    };
    var target = {
        set q(value) {
            log.push(`set q ${value}`);
        },
    };

    ({ p: (log.push("target base"), target).q } = source);
    expect(log).toEqual(["target base", "get p", "set q 42"]);
});

test("object destructuring evaluates computed MemberExpression target before source property", () => {
    var log = [];
    var source = {
        get p() {
            log.push("get p");
            return undefined;
        },
    };
    var target = {
        set q(value) {
            log.push(`set q ${value}`);
        },
    };
    function sourceKey() {
        log.push("source key");
        return {
            toString() {
                log.push("source key toString");
                return "p";
            },
        };
    }
    function targetKey() {
        log.push("target key");
        return "q";
    }

    ({ [sourceKey()]: target[targetKey()] = (log.push("default"), 7) } = source);
    expect(log).toEqual(["source key", "source key toString", "target key", "get p", "default", "set q 7"]);
});

test("object rest destructuring evaluates MemberExpression target before copying properties", () => {
    var log = [];
    var source = {
        a: 1,
        get b() {
            log.push("get b");
            return 2;
        },
    };
    var target = {};

    ({ a, ...(log.push("target base"), target).rest } = source);
    expect(log).toEqual(["target base", "get b"]);
    expect(target.rest).toEqual({ b: 2 });
});

test("named class expression as default value in array destructuring", () => {
    var x;
    [x = class C {}] = [undefined];
    expect(typeof x).toBe("function");
    expect(x.name).toBe("C");
});

test("class with method referencing class name in destructuring default", () => {
    var x;
    [
        x = class C {
            static getName() {
                return C.name;
            }
        },
    ] = [undefined];
    expect(x.getName()).toBe("C");
});

test("arrow function as default value in array destructuring", () => {
    var x;
    [x = () => 42] = [undefined];
    expect(x()).toBe(42);
});

test("arrow function capturing outer variable in destructuring default", () => {
    var outer = "hello";
    var x;
    [x = () => outer] = [undefined];
    expect(x()).toBe("hello");
});

test("nested destructuring with class expression defaults", () => {
    var a, b;
    [a = class {}, [b = class {}]] = [undefined, [undefined]];
    expect(typeof a).toBe("function");
    expect(typeof b).toBe("function");
});

test("object destructuring with function expression accessing parameter", () => {
    var x;
    ({
        x = function f(n) {
            return n > 0 ? n * f(n - 1) : 1;
        },
    } = {});
    expect(x(5)).toBe(120);
});

test("default value with eval in array destructuring", () => {
    var x;
    [x = eval("42")] = [undefined];
    expect(x).toBe(42);
});

test("array destructuring default value does not leak class name", () => {
    var x;
    [x = class C {}] = [undefined];
    expect(() => C).toThrowWithMessage(ReferenceError, "'C' is not defined");
});