load("test-common.js"); try { assert(Object.getOwnPropertyDescriptor(new Proxy({}, { getOwnPropertyDescriptor: null }), "a") === undefined); assert(Object.getOwnPropertyDescriptor(new Proxy({}, { getOwnPropertyDescriptor: undefined }), "a") === undefined); assert(Object.getOwnPropertyDescriptor(new Proxy({}, {}), "a") === undefined); let o = {}; let p = new Proxy(o, { getOwnPropertyDescriptor(target, property) { assert(target === o); assert(property === "foo"); } }); Object.getOwnPropertyDescriptor(p, "foo"); o = { foo: "bar" }; Object.defineProperty(o, "baz", { value: "qux", enumerable: false, configurable: true, writable: false }); p = new Proxy(o, { getOwnPropertyDescriptor(target, property) { if (property === "baz") return Object.getOwnPropertyDescriptor(target, "baz"); return { value: target[property], enumerable: false, configurable: true, writable: true }; } }); let d = Object.getOwnPropertyDescriptor(p, "baz"); assert(d.configurable === true); assert(d.enumerable === false); assert(d.writable === false); assert(d.value === "qux"); assert(d.get === undefined); assert(d.set === undefined); d = Object.getOwnPropertyDescriptor(p, "foo"); assert(d.configurable === true); assert(d.enumerable === false); assert(d.writable === true); assert(d.value === "bar"); assert(d.get === undefined); assert(d.set === undefined); // Invariants assertThrowsError(() => { Object.getOwnPropertyDescriptor(new Proxy({}, { getOwnPropertyDescriptor: 1 })); }, { error: TypeError, message: "Proxy handler's getOwnPropertyDescriptor trap wasn't undefined, null, or callable", }); assertThrowsError(() => { Object.getOwnPropertyDescriptor(new Proxy({}, { getOwnPropertyDescriptor() { return 1; }, })); }, { error: TypeError, message: "Proxy handler's getOwnPropertyDescriptor trap violates invariant: must return an object or undefined", }); o = {}; Object.defineProperty(o, "foo", { value: 10, configurable: false }); p = new Proxy(o, { getOwnPropertyDescriptor() { return undefined; }, }); assert(Object.getOwnPropertyDescriptor(p, "bar") === undefined); assertThrowsError(() => { Object.getOwnPropertyDescriptor(p, "foo"); }, { error: TypeError, message: "Proxy handler's getOwnPropertyDescriptor trap violates invariant: cannot return undefined for a property on the target which is a non-configurable property", }); Object.defineProperty(o, "baz", { value: 20, configurable: true, writable: true, enumerable: true }); Object.preventExtensions(o); assertThrowsError(() => { Object.getOwnPropertyDescriptor(p, "baz"); }, { error: TypeError, message: "Proxy handler's getOwnPropertyDescriptor trap violates invariant: cannot report a property as being undefined if it exists as an own property of the target and the target is non-extensible", }); o = {}; Object.defineProperty(o, "v1", { value: 10, configurable: false }); Object.defineProperty(o, "v2", { value: 10, configurable: false, enumerable: true }); Object.defineProperty(o, "v3", { configurable: false, get() { return 1; } }); Object.defineProperty(o, "v4", { value: 10, configurable: false, writable: false, enumerable: true }); assertThrowsError(() => { Object.getOwnPropertyDescriptor(new Proxy(o, { getOwnPropertyDescriptor() { return { configurable: true }; }, }), "v1"); }, { error: TypeError, message: "Proxy handler's getOwnPropertyDescriptor trap violates invariant: invalid property descriptor for existing property on the target", }); assertThrowsError(() => { Object.getOwnPropertyDescriptor(new Proxy(o, { getOwnPropertyDescriptor() { return { enumerable: false }; }, }), "v2"); }, { error: TypeError, message: "Proxy handler's getOwnPropertyDescriptor trap violates invariant: invalid property descriptor for existing property on the target", }); assertThrowsError(() => { Object.getOwnPropertyDescriptor(new Proxy(o, { getOwnPropertyDescriptor() { return { value: 10 }; }, }), "v3"); }, { error: TypeError, message: "Proxy handler's getOwnPropertyDescriptor trap violates invariant: invalid property descriptor for existing property on the target", }); assertThrowsError(() => { Object.getOwnPropertyDescriptor(new Proxy(o, { getOwnPropertyDescriptor() { return { value: 10, writable: true }; }, }), "v4"); }, { error: TypeError, message: "Proxy handler's getOwnPropertyDescriptor trap violates invariant: invalid property descriptor for existing property on the target", }); o = {}; Object.defineProperty(o, "v", { configurable: true }); assertThrowsError(() => { Object.getOwnPropertyDescriptor(new Proxy(o, { getOwnPropertyDescriptor() { return { configurable: false }; }, }), "v"); }, { error: TypeError, message: "Proxy handler's getOwnPropertyDescriptor trap violates invariant: cannot report target's property as non-configurable if the property does not exist, or if it is configurable", }); console.log("PASS"); } catch (e) { console.log("FAIL: " + e); }