golden/modules/test_util_test.js

import {eventPromise} from './test_util';

describe('test utilities', () => {

  describe('eventPromise', () => {
    let el; // Element that we'll dispatch custom events from.
    let clock;

    beforeEach(() => {
      el = document.createElement('div');
      document.body.appendChild(el);
      clock = sinon.useFakeTimers();
    });

    afterEach(() => {
      document.body.removeChild(el);
      clock.restore();
    });

    it('resolves when event is caught', async () => {
      const hello = eventPromise('hello');
      el.dispatchEvent(new CustomEvent('hello', {bubbles: true, detail: 'hi'}));
      const ev = await hello;
      expect(ev.detail).to.equal('hi');
    });

    it('times out if event is not caught', async () => {
      const hello = eventPromise('hello', 5000);
      el.dispatchEvent(new CustomEvent('bye', {bubbles: true}));
      clock.tick(10000);
      try {
        await hello;
        expect.fail('promise should not have resolved');
      } catch(error) {
        expect(error.message).to.equal(
          'timed out after 5000 ms while waiting to catch event "hello"');
      }
    });

    it('never times out if timeoutMillis=0', async () => {
      const hello = eventPromise('hello', 0);
      clock.tick(Number.MAX_SAFE_INTEGER);
      el.dispatchEvent(new CustomEvent('hello', {bubbles: true, detail: 'hi'}));
      const ev = await hello;
      expect(ev.detail).to.equal('hi');
    });
  });
});