osmd-audio-player/dist/internals/EventEmitter.test.js

OSMD audio player

import { EventEmitter } from "./EventEmitter";
describe("EventEmitter", () => {
    test("Single subscriber", () => {
        const emitter = new EventEmitter();
        const cb = jest.fn(() => { });
        emitter.on("test-event", cb);
        emitter.emit("test-event");
        expect(cb).toHaveBeenCalledTimes(1);
    });
    test("Single subscriber, with arguments", () => {
        const emitter = new EventEmitter();
        const cb = jest.fn(() => { });
        emitter.on("test-event", cb);
        emitter.emit("test-event", 1, 2);
        expect(cb).toHaveBeenCalledTimes(1);
        expect(cb).toHaveBeenCalledWith(1, 2);
    });
    test("Multiple subscribers", () => {
        const emitter = new EventEmitter();
        const cb1 = jest.fn(() => { });
        const cb2 = jest.fn(() => { });
        emitter.on("test-event", cb1);
        emitter.on("test-event", cb2);
        emitter.emit("test-event");
        expect(cb1).toHaveBeenCalledTimes(1);
        expect(cb2).toHaveBeenCalledTimes(1);
    });
    test("Multiple events", () => {
        const emitter = new EventEmitter();
        const cb1 = jest.fn(() => { });
        const cb2 = jest.fn(() => { });
        const cb3 = jest.fn(() => { });
        emitter.on("event1", cb1);
        emitter.on("event2", cb2);
        emitter.on("event3", cb3);
        emitter.emit("event1");
        emitter.emit("event2");
        expect(cb1).toHaveBeenCalledTimes(1);
        expect(cb2).toHaveBeenCalledTimes(1);
        expect(cb3).toHaveBeenCalledTimes(0);
    });
});