index.test.js

const { Timeout, Interval } = require(".");
require("jest");

beforeEach(() => {
    jest.useFakeTimers();
});

describe("state tests", () => {
    test("state is set to 0 after creation of timer", () => {
        const to = new Timeout(() => { }, 0);
        expect(to.state).toBe(0);
    });

    test("state is set to 1 when timer has been started", () => {
        const waitTime = 1000;
        const callback = jest.fn();
        const to = new Timeout(callback, waitTime);
        to.start();
        expect(to.state).toBe(1);
    });

    test("state is set to 3 and callback is called after timer is completed", () => {
        const waitTime = 1000;
        const callback = jest.fn();
        const to = new Timeout(callback, waitTime);
        to.start();

        jest.runAllTimers();
        expect(to.state).toBe(3);
        expect(callback).toBeCalled();
        expect(callback).toHaveBeenCalledTimes(1);
    });
});

describe("time start tests", () => {
    test("timeout is not started when autostart is false", () => {
        const to = new Timeout(() => { }, 0, false);
        expect(setTimeout).toHaveBeenCalledTimes(0);
    });

    test("timeout is not started when autostart is not specified", () => {
        const to = new Timeout(() => { }, 0);
        expect(setTimeout).toHaveBeenCalledTimes(0);
    });

    test("timeout is started when autostart is true", () => {
        const waitTime = 1000;
        const to = new Timeout(() => { }, waitTime, true);
        expect(setTimeout).toHaveBeenCalledTimes(1);
        expect(setTimeout).toHaveBeenLastCalledWith(expect.any(Function), waitTime);
    });

    test("interval is not started when autostart is false", () => {
        const to = new Interval(() => to.stop(), 1, false);
        expect(setInterval).toHaveBeenCalledTimes(0);
    });

    test("interval is not started when autostart is not specified", () => {
        const to = new Interval(() => to.stop(), 1);
        expect(setInterval).toHaveBeenCalledTimes(0);
    });

    test("interval is started when autostart is true", () => {
        const waitTime = 1000;
        const to = new Interval(() => to.stop(), waitTime, true);
        expect(setInterval).toHaveBeenCalledTimes(1);
        expect(setInterval).toHaveBeenLastCalledWith(expect.any(Function), waitTime);
    });
});