112 lines
4.5 KiB
JavaScript
112 lines
4.5 KiB
JavaScript
describe("[[DefineProperty]] trap normal behavior", () => {
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test("forwarding when not defined in handler", () => {
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let p = new Proxy({}, { defineProperty: null });
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expect(Object.defineProperty(p, "foo", {})).toBe(p);
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p = new Proxy({}, { defineProperty: undefined });
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expect(Object.defineProperty(p, "foo", {})).toBe(p);
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p = new Proxy({}, {});
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expect(Object.defineProperty(p, "foo", {})).toBe(p);
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});
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test("correct arguments passed to trap", () => {
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let o = {};
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p = new Proxy(o, {
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defineProperty(target, name, descriptor) {
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expect(target).toBe(o);
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expect(name).toBe("foo");
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expect(descriptor.configurable).toBe(true);
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expect(descriptor.enumerable).toBeUndefined();
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expect(descriptor.writable).toBe(true);
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expect(descriptor.value).toBe(10);
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expect(descriptor.get).toBeUndefined();
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expect(descriptor.set).toBeUndefined();
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return true;
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},
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});
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Object.defineProperty(p, "foo", { configurable: true, writable: true, value: 10 });
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});
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test("optionally ignoring the define call", () => {
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let o = {};
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let p = new Proxy(o, {
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defineProperty(target, name, descriptor) {
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if (target[name] === undefined)
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Object.defineProperty(target, name, descriptor);
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return true;
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},
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});
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Object.defineProperty(p, "foo", { value: 10, enumerable: true, configurable: false, writable: true });
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let d = Object.getOwnPropertyDescriptor(p, "foo");
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expect(d.enumerable).toBe(true);
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expect(d.configurable).toBe(false);
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expect(d.writable).toBe(true);
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expect(d.value).toBe(10);
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expect(d.get).toBeUndefined();
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expect(d.set).toBeUndefined();
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Object.defineProperty(p, "foo", { value: 20, enumerable: true, configurable: false, writable: true });
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d = Object.getOwnPropertyDescriptor(p, "foo");
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expect(d.enumerable).toBe(true);
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expect(d.configurable).toBe(false);
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expect(d.writable).toBe(true);
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expect(d.value).toBe(10);
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expect(d.get).toBeUndefined();
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expect(d.set).toBeUndefined();
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});
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});
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describe("[[DefineProperty]] invariants", () => {
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test("trap can't return false", () => {
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let p = new Proxy({}, {
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defineProperty() { return false; }
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});
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expect(() => {
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Object.defineProperty(p, "foo", {});
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}).toThrowWithMessage(TypeError, "Object's [[DefineProperty]] method returned false");
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});
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test("trap cannot return true for a non-extensible target if the property does not exist", () => {
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let o = {};
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Object.preventExtensions(o);
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let p = new Proxy(o, {
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defineProperty() {
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return true;
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}
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});
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expect(() => {
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Object.defineProperty(p, "foo", {});
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}).toThrowWithMessage(TypeError, "Proxy handler's defineProperty trap violates invariant: a property cannot be reported as being defined if the property does not exist on the target and the target is non-extensible");
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});
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test("trap cannot return true for a non-configurable property if it doesn't already exist on the target", () => {
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let o = {};
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Object.defineProperty(o, "foo", { value: 10, configurable: true });
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let p = new Proxy(o, {
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defineProperty() {
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return true;
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},
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});
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expect(() => {
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Object.defineProperty(p, "bar", { value: 6, configurable: false });
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}).toThrowWithMessage(TypeError, "Proxy handler's defineProperty trap violates invariant: a property cannot be defined as non-configurable if it does not already exist on the target object");
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});
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test("trap cannot return true for a non-configurable property if it already exists as a configurable property", () => {
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let o = {};
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Object.defineProperty(o, "foo", { value: 10, configurable: true });
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let p = new Proxy(o, {
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defineProperty() {
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return true;
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},
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});
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expect(() => {
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Object.defineProperty(p, "foo", { value: 6, configurable: false });
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}).toThrowWithMessage(TypeError, "Proxy handler's defineProperty trap violates invariant: a property cannot be defined as non-configurable if it already exists on the target object as a configurable property");
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})
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});
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