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describe("normal functionality", () => {
test("non-configurable property", () => {
let o = {};
Object.defineProperty(o, "foo", { value: 1, writable: false, enumerable: false });
expect(o.foo).toBe(1);
o.foo = 2;
expect(o.foo).toBe(1);
expect(o).not.toHaveConfigurableProperty("foo");
expect(o).not.toHaveEnumerableProperty("foo");
expect(o).not.toHaveWritableProperty("foo");
expect(o).toHaveValueProperty("foo", 1);
});
test("array index getter", () => {
let o = {};
Object.defineProperty(o, 2, { get() { return 10; } });
expect(o[2]).toBe(10);
});
test("configurable property", () => {
let o = {};
Object.defineProperty(o, "foo", { value: "hi", writable: true, enumerable: true });
expect(o.foo).toBe("hi");
o.foo = "ho";
expect(o.foo).toBe("ho");
expect(o).not.toHaveConfigurableProperty("foo");
expect(o).toHaveEnumerableProperty("foo");
expect(o).toHaveWritableProperty("foo");
expect(o).toHaveValueProperty("foo", "ho");
});
test("reconfigure configurable property", () => {
let o = {};
Object.defineProperty(o, "foo", { value: 9, configurable: true, writable: false });
Object.defineProperty(o, "foo", { configurable: true, writable: true });
expect(o).toHaveConfigurableProperty("foo");
expect(o).toHaveWritableProperty("foo");
expect(o).not.toHaveEnumerableProperty("foo");
expect(o).toHaveValueProperty("foo", 9);
});
test("define accessor", () => {
let o = {};
Object.defineProperty(o, "foo", {
configurable: true,
get() {
return o.secret_foo + 1;
},
set(value) {
this.secret_foo = value + 1;
},
});
o.foo = 10;
expect(o.foo).toBe(12);
o.foo = 20;
expect(o.foo).toBe(22);
Object.defineProperty(o, "foo", { configurable: true, value: 4 });
expect(o.foo).toBe(4);
expect(o.foo = 5).toBe(5);
expect(o.foo = 4).toBe(4);
});
});
describe("errors", () => {
test("redefine non-configurable property", () => {
let o = {};
Object.defineProperty(o, "foo", { value: 1, writable: true, enumerable: true });
expect(() => {
Object.defineProperty(o, "foo", { value: 2, writable: false, enumerable: true });
}).toThrowWithMessage(TypeError, "Cannot change attributes of non-configurable property 'foo'");
});
test("cannot define 'value' and 'get' in the same descriptor", () => {
let o = {};
expect(() => {
Object.defineProperty(o, "a", {
get() {},
value: 9,
});
}).toThrowWithMessage(TypeError, "Accessor property descriptor cannot specify a value or writable key");
});
test("cannot define 'value' and 'set' in the same descriptor", () => {
let o = {};
expect(() => {
Object.defineProperty(o, "a", {
set() {},
writable: true,
});
}).toThrowWithMessage(TypeError, "Accessor property descriptor cannot specify a value or writable key");
});
test("redefine non-configurable accessor", () => {
let o = {};
Object.defineProperty(o, "foo", {
configurable: false,
get() {
return this.secret_foo + 2;
},
set(value) {
o.secret_foo = value + 2;
},
});
expect(() => {
Object.defineProperty(o, "foo", {
configurable: false,
get() {
return this.secret_foo + 2;
},
});
}).toThrowWithMessage(TypeError, "Cannot change attributes of non-configurable property 'foo'");
});
});
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