describe("parsing", () => {
    test("single name", () => {
        expect(`var { a } = {};`).toEval();
        expect(`const { a } = {};`).toEval();
        expect(`let { a } = {};`).toEval();
    });

    test("single name with rest values", () => {
        expect(`var { a, ...rest } = {};`).toEval();
        expect(`const { a, ...rest } = {};`).toEval();
        expect(`let { a, ...rest } = {};`).toEval();
    });

    test("single aliased name", () => {
        expect(`var { a: b } = {};`).toEval();
        expect(`const { a: b } = {};`).toEval();
        expect(`let { a: b } = {};`).toEval();
    });

    test("single aliased name with rest values", () => {
        expect(`var { a: b, ...rest } = {};`).toEval();
        expect(`const { a: b, ...rest } = {};`).toEval();
        expect(`let { a: b, ...rest } = {};`).toEval();
    });

    test("array destructuring patterns", () => {
        expect(`var [ a ] = [];`).toEval();
        expect(`const [ a ] = [];`).toEval();
        expect(`let [ a ] = [];`).toEval();
    });

    test("destructuring assignment with rest assignments, array patterns", () => {
        expect(`var [ a, ...rest ] = [];`).toEval();
        expect(`const [ a, ...rest ] = [];`).toEval();
        expect(`let [ a, ...rest ] = [];`).toEval();
    });

    test("destructuring assignment with rest names, array patterns with recursive patterns", () => {
        expect(`var [ a, [ ...rest ] ] = [];`).toEval();
        expect(`const [ a, [ ...rest ] ] = [];`).toEval();
        expect(`let [ a, [ ...rest ] ] = [];`).toEval();
    });

    test("destructuring assignment with rest names, array patterns with recursive patterns 2", () => {
        expect(`var [ a, [ ...{length} ] ] = [];`).toEval();
        expect(`const [ a, [ ...{length} ] ] = [];`).toEval();
        expect(`let [ a, [ ...{length} ] ] = [];`).toEval();
    });

    test("function parameters cannot use member expressions", () => {
        expect("function f([a.b]) {}").not.toEval();
        expect("function f([b[0]]) {}").not.toEval();

        expect("function f({c:a.b}) {}").not.toEval();
        expect("function f({a:b[0]}) {}").not.toEval();

        expect("([a.b]) => 1").not.toEval();
        expect("([b[0]]) => 2").not.toEval();

        expect("({c:a.b}) => 3").not.toEval();
        expect("({a:b[0]}) => 4").not.toEval();
    });

    test("assignment patterns cannot use parenthesized nested object or array patterns", () => {
        expect("var a, b; ({ a: ({ b: b }) } = { a: { b: 42 } });").not.toEval();
        expect("var a, b; ({ a: ([b]) } = { a: [42] });").not.toEval();

        expect("var a, b; ({ a: (a), b } = { a: 1, b: 2 });").toEval();
        expect("var a, b; [(a), b] = [1, 2];").toEval();
    });
});

describe("evaluating", () => {
    test("single name", () => {
        let o = { a: 1 };
        {
            var { a } = o;
            expect(a).toBe(o.a);
        }
        {
            const { a } = o;
            expect(a).toBe(o.a);
        }
        {
            let { a } = o;
            expect(a).toBe(o.a);
        }
    });

    test("single name with rest values", () => {
        let o = { a: 1, b: 2 };
        {
            var { a, ...b } = o;
            expect(a).toBe(o.a);
            expect(b).toEqual({ b: 2 });
        }
        {
            const { a, ...b } = o;
            expect(a).toBe(o.a);
            expect(b).toEqual({ b: 2 });
        }
        {
            let { a, ...b } = o;
            expect(a).toBe(o.a);
            expect(b).toEqual({ b: 2 });
        }
    });

    test("single aliased name", () => {
        let o = { a: 1 };
        {
            var { a: x } = o;
            expect(x).toBe(o.a);
        }
        {
            const { a: x } = o;
            expect(x).toBe(o.a);
        }
        {
            let { a: x } = o;
            expect(x).toBe(o.a);
        }
    });

    test("single aliased name with rest values", () => {
        let o = { a: 1, b: 2 };
        {
            var { a: x, ...b } = o;
            expect(x).toBe(o.a);
            expect(b).toEqual({ b: 2 });
        }
        {
            const { a: x, ...b } = o;
            expect(x).toBe(o.a);
            expect(b).toEqual({ b: 2 });
        }
        {
            let { a: x, ...b } = o;
            expect(x).toBe(o.a);
            expect(b).toEqual({ b: 2 });
        }
    });

    test("array patterns", () => {
        let o = [1, 2, 3, 4];
        {
            var [a, b] = o;
            expect(a).toBe(o[0]);
            expect(b).toBe(o[1]);
        }
        {
            const [a, b] = o;
            expect(a).toBe(o[0]);
            expect(b).toBe(o[1]);
        }
        {
            let [a, b] = o;
            expect(a).toBe(o[0]);
            expect(b).toBe(o[1]);
        }
    });

    test("destructuring assignment with rest names, array patterns", () => {
        let o = [1, 2, 3, 4];
        {
            var [a, ...b] = o;
            expect(a).toBe(o[0]);
            expect(b).toEqual(o.slice(1));
        }
        {
            const [a, ...b] = o;
            expect(a).toBe(o[0]);
            expect(b).toEqual(o.slice(1));
        }
        {
            let [a, ...b] = o;
            expect(a).toBe(o[0]);
            expect(b).toEqual(o.slice(1));
        }
    });

    test("destructuring assignment with rest names, array patterns with recursive patterns", () => {
        let o = [1, [2, 3, 4]];
        {
            var [a, [b, ...c]] = o;
            expect(a).toBe(o[0]);
            expect(b).toBe(o[1][0]);
            expect(c).toEqual(o[1].slice(1));
        }
        {
            const [a, [b, ...c]] = o;
            expect(a).toBe(o[0]);
            expect(b).toBe(o[1][0]);
            expect(c).toEqual(o[1].slice(1));
        }
        {
            let [a, [b, ...c]] = o;
            expect(a).toBe(o[0]);
            expect(b).toBe(o[1][0]);
            expect(c).toEqual(o[1].slice(1));
        }
    });

    test("destructuring assignment with rest names, array patterns with recursive patterns 2", () => {
        let o = [1, [2, 3, 4]];
        {
            var [a, [...{ length }]] = o;
            expect(a).toBe(o[0]);
            expect(length).toBe(o[1].length);
        }
        {
            const [a, [...{ length }]] = o;
            expect(a).toBe(o[0]);
            expect(length).toBe(o[1].length);
        }
        {
            let [a, [...{ length }]] = o;
            expect(a).toBe(o[0]);
            expect(length).toBe(o[1].length);
        }
        {
            expect(() => {
                let [a, b, [...{ length }]] = o;
            }).toThrowWithMessage(TypeError, "ToObject on null or undefined");
        }
    });

    test("patterns with default", () => {
        let o = { a: 1 };
        let { x = "foo", a = "bar" } = o;
        expect(x).toBe("foo");
        expect(a).toBe(o.a);
    });

    test("can use big int values as number-like properties", () => {
        let o = { "99999999999999999": 1 };
        let { 123n: a = "foo", 99999999999999999n: b = "bar" } = o;
        expect(a).toBe("foo");
        expect(b).toBe(1);
    });
});

describe("array iterator closing", () => {
    test("target evaluation throwing closes without stepping", () => {
        let nextCount = 0;
        let returnCount = 0;
        let thrown = new Error("target");
        let iterator = {
            next() {
                ++nextCount;
                return { done: true };
            },
            return() {
                ++returnCount;
                return {};
            },
        };
        let iterable = {
            [Symbol.iterator]() {
                return iterator;
            },
        };
        let thrower = () => {
            throw thrown;
        };

        expect(() => {
            (0, ([{}[thrower()]] = iterable));
        }).toThrow(thrown);
        expect(nextCount).toBe(0);
        expect(returnCount).toBe(1);
    });

    test("iterator next throwing is not closed", () => {
        let returnCount = 0;
        let thrown = new Error("next");
        let iterator = {
            next() {
                throw thrown;
            },
            return() {
                ++returnCount;
                return {};
            },
        };
        let iterable = {
            [Symbol.iterator]() {
                return iterator;
            },
        };

        expect(() => {
            let [value] = iterable;
        }).toThrow(thrown);
        expect(returnCount).toBe(0);
    });

    test("default initializer throwing closes and preserves the original throw completion", () => {
        let returnCount = 0;
        let thrown = new Error("default");
        let iterator = {
            next() {
                return { done: false, value: undefined };
            },
            return() {
                ++returnCount;
                return null;
            },
        };
        let iterable = {
            [Symbol.iterator]() {
                return iterator;
            },
        };
        let thrower = () => {
            throw thrown;
        };

        expect(() => {
            [{} = thrower()] = iterable;
        }).toThrow(thrown);
        expect(returnCount).toBe(1);
    });

    test("generator return through rest target closes the iterator", () => {
        let returnCount = 0;
        let iterator = {
            next() {
                throw new Error("unreachable");
            },
            return() {
                ++returnCount;
                return {};
            },
        };
        let iterable = {
            [Symbol.iterator]() {
                return iterator;
            },
        };
        function* generator() {
            [...{}[yield]] = iterable;
        }

        let it = generator();
        it.next();
        let result = it.return(444);
        expect(returnCount).toBe(1);
        expect(result.value).toBe(444);
        expect(result.done).toBe(true);
    });
});