114 lines
3.3 KiB
JavaScript
114 lines
3.3 KiB
JavaScript
describe("[[Set]] trap normal behavior", () => {
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test("forwarding when not defined in handler", () => {
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expect((new Proxy({}, { set: undefined }).foo = 1)).toBe(1);
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expect((new Proxy({}, { set: null }).foo = 1)).toBe(1);
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expect((new Proxy({}, {}).foo = 1)).toBe(1);
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});
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test("correct arguments supplied to trap", () => {
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let o = {};
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let p = new Proxy(o, {
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set(target, prop, value, receiver) {
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expect(target).toBe(o);
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expect(prop).toBe("foo");
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expect(value).toBe(10);
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expect(receiver).toBe(p);
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return true;
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},
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});
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p.foo = 10;
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});
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test("correct arguments passed to trap even for number", () => {
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let o = {};
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let p = new Proxy(o, {
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set(target, prop, value, receiver) {
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expect(target).toBe(o);
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expect(prop).toBe("1");
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expect(value).toBe(10);
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expect(receiver).toBe(p);
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return true;
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},
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});
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p[1] = 10;
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});
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test("conditional return value", () => {
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let p = new Proxy(
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{},
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{
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set(target, prop, value) {
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if (target[prop] === value) {
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target[prop] *= 2;
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} else {
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target[prop] = value;
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}
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},
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}
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);
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p.foo = 10;
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expect(p.foo).toBe(10);
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p.foo = 10;
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expect(p.foo).toBe(20);
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p.foo = 10;
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expect(p.foo).toBe(10);
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p[Symbol.hasInstance] = "foo";
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expect(p[Symbol.hasInstance]).toBe("foo");
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});
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test("custom receiver value", () => {
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const o = {};
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const r = {};
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let p = new Proxy(o, {
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set(target, property, value, receiver) {
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receiver[property] = value;
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return true;
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},
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});
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expect(Reflect.set(p, "foo", 42, r)).toBe(true);
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expect(o.foo).toBeUndefined();
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expect(r.foo).toBe(42);
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});
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});
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describe("[[Set]] invariants", () => {
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test("cannot return true for a non-configurable, non-writable property", () => {
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let o = {};
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Object.defineProperty(o, "foo", { value: 10 });
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let p = new Proxy(o, {
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set() {
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return true;
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},
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});
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expect(() => {
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p.foo = 12;
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}).toThrowWithMessage(
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TypeError,
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"Proxy handler's set trap violates invariant: cannot return true for a property on the target which is a non-configurable, non-writable own data property"
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);
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});
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test("cannot return true for a non-configurable accessor property with no setter", () => {
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let o = {};
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Object.defineProperty(o, "foo", { get() {} });
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let p = new Proxy(o, {
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set() {
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return true;
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},
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});
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expect(() => {
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p.foo = 12;
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}).toThrowWithMessage(
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TypeError,
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"Proxy handler's set trap violates invariant: cannot return true for a property on the target which is a non-configurable own accessor property with an undefined set attribute"
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);
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});
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});
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