2cf8649d0e
We can't assume that property names can be converted to strings anymore,
as we have symbols. Use name.to_value() instead.
This makes something like this possible:
new Proxy(Object, { get(t, p) { return t[p] } })[Symbol.hasInstance]
84 lines
2.5 KiB
JavaScript
84 lines
2.5 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("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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});
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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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