describe("basic functionality", () => { test("length", () => { expect(Object.entries).toHaveLength(1); expect(Object.entries(true)).toHaveLength(0); expect(Object.entries(45)).toHaveLength(0); expect(Object.entries(-998)).toHaveLength(0); expect(Object.entries("abcd")).toHaveLength(4); expect(Object.entries([1, 2, 3])).toHaveLength(3); expect(Object.entries({ a: 1, b: 2, c: 3 })).toHaveLength(3); }); test("entries with object", () => { let entries = Object.entries({ foo: 1, bar: 2, baz: 3 }); expect(entries).toEqual([ ["foo", 1], ["bar", 2], ["baz", 3], ]); }); test("entries with objects with symbol keys", () => { let entries = Object.entries({ foo: 1, [Symbol("bar")]: 2, baz: 3 }); expect(entries).toEqual([ ["foo", 1], ["baz", 3], ]); }); test("entries with array", () => { entries = Object.entries(["a", "b", "c"]); expect(entries).toEqual([ ["0", "a"], ["1", "b"], ["2", "c"], ]); }); test("ignores non-enumerable properties", () => { let obj = { foo: 1 }; Object.defineProperty(obj, "getFoo", { value: function () { return this.foo; }, }); let entries = Object.entries(obj); expect(entries).toEqual([["foo", 1]]); }); }); describe("errors", () => { test("null argument", () => { expect(() => { Object.entries(null); }).toThrowWithMessage(TypeError, "ToObject on null or undefined"); }); test("undefined argument", () => { expect(() => { Object.entries(undefined); }).toThrowWithMessage(TypeError, "ToObject on null or undefined"); }); });