hls.js/tests/unit/utils/texttrack-utils.js

import {
  sendAddTrackEvent,
  clearCurrentCues,
} from '../../../src/utils/texttrack-utils';
import sinon from 'sinon';

describe('text track utils', function () {
  const cues = [
    {
      begin: 0,
      end: 5,
      text: 'First 5',
    },
    {
      begin: 5,
      end: 10,
      text: 'Last 5',
    },
  ];

  let track;
  let video;

  beforeEach(function () {
    video = document.createElement('video');
    track = video.addTextTrack('subtitles', 'test');
    cues.forEach((cue) => {
      track.addCue(new VTTCue(cue.begin, cue.end, cue.text));
    });
  });

  describe('synthetic addtrack event', function () {
    it('should have the provided track as data', function (done) {
      const dispatchSpy = sinon.spy(video, 'dispatchEvent');
      video.addEventListener('addtrack', function (e) {
        expect(e.track).to.equal(track);
        done();
      });

      sendAddTrackEvent(track, video);
      expect(dispatchSpy.calledOnce).to.be.true;
    });

    it('should fallback to document.createEvent if window.Event constructor throws', function (done) {
      const stub = sinon.stub(self, 'Event');
      stub.throws();

      const spy = sinon.spy(document, 'createEvent');

      video.addEventListener('addtrack', function (e) {
        expect(e.track).to.equal(track);
        done();
      });

      sendAddTrackEvent(track, video);
      expect(spy.calledOnce).to.be.true;
    });
  });

  describe('clear current cues', function () {
    it('should not fail with empty cue list', function () {
      const emptyTrack = video.addTextTrack('subtitles', 'empty');
      expect(clearCurrentCues(emptyTrack)).to.not.throw;
    });

    it('should clear the cues from track', function () {
      clearCurrentCues(track);
      expect(track.cues.length).to.equal(0);
    });
  });
});