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- describe("errors", () => {
- test("called with non-Object", () => {
- expect(() => {
- Iterator.from(Symbol.hasInstance);
- }).toThrowWithMessage(TypeError, "obj is not an object");
- });
- test("@@iterator is not callable", () => {
- const iterable = {};
- iterable[Symbol.iterator] = 12389;
- expect(() => {
- Iterator.from(iterable);
- }).toThrowWithMessage(TypeError, "12389 is not a function");
- });
- test("@@iterator throws an exception", () => {
- function TestError() {}
- const iterable = {};
- iterable[Symbol.iterator] = () => {
- throw new TestError();
- };
- expect(() => {
- Iterator.from(iterable);
- }).toThrow(TestError);
- });
- test("@@iterator return a non-Object", () => {
- const iterable = {};
- iterable[Symbol.iterator] = () => {
- return Symbol.hasInstance;
- };
- expect(() => {
- Iterator.from(iterable);
- }).toThrowWithMessage(TypeError, "iterator is not an object");
- });
- });
- describe("normal behavior", () => {
- test("length is 1", () => {
- expect(Iterator.from).toHaveLength(1);
- });
- test("create Iterator from a string", () => {
- const iterator = Iterator.from("ab");
- let result = iterator.next();
- expect(result.value).toBe("a");
- expect(result.done).toBeFalse();
- result = iterator.next();
- expect(result.value).toBe("b");
- expect(result.done).toBeFalse();
- result = iterator.next();
- expect(result.value).toBeUndefined();
- expect(result.done).toBeTrue();
- });
- test("create Iterator from generator", () => {
- function* generator() {
- yield 1;
- yield 2;
- }
- const iterator = Iterator.from(generator());
- let result = iterator.next();
- expect(result.value).toBe(1);
- expect(result.done).toBeFalse();
- result = iterator.next();
- expect(result.value).toBe(2);
- expect(result.done).toBeFalse();
- result = iterator.next();
- expect(result.value).toBeUndefined();
- expect(result.done).toBeTrue();
- });
- test("create Iterator from iterator-like object", () => {
- class TestIterator {
- next() {
- if (this.#first) {
- this.#first = false;
- return { value: 1, done: false };
- }
- return { value: undefined, done: true };
- }
- #first = true;
- }
- const testIterator = new TestIterator();
- const iterator = Iterator.from(testIterator);
- let result = iterator.next();
- expect(result.value).toBe(1);
- expect(result.done).toBeFalse();
- result = iterator.next();
- expect(result.value).toBeUndefined();
- expect(result.done).toBeTrue();
- });
- });
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