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<title>Removing a track from a MediaStream</title>
<link rel="author" title="Dominique Hazael-Massieux" href="mailto:dom@w3.org"/>
<link rel="help" href="http://dev.w3.org/2011/webrtc/editor/getusermedia.html#widl-MediaStreamTrackList-remove-void-MediaStreamTrack-track">
<link rel="help" href="http://dev.w3.org/2011/webrtc/editor/getusermedia.html#event-mediastream-removetrack">
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<p class="instructions">When prompted, accept to share your audio stream, then your video stream.</p>
<h1 class="instructions">Description</h1>
<p class="instructions">This test checks that removinging a track from a MediaStream works as expected.</p>
<video id="video" height="120" width="160" autoplay muted></video>
<audio id="audio" autoplay muted></audio>
<div id='log'></div>
<script src=/resources/testharness.js></script>
<script src=/resources/testharnessreport.js></script>
<script>

promise_test(async t => {
  const stream = await navigator.mediaDevices.getUserMedia({video: true, audio: true});
  const tracks = stream.getTracks();
  t.add_cleanup(() => tracks.forEach(track => track.stop()));
  const stream2 = await navigator.mediaDevices.getUserMedia({audio: true});
  tracks.push(...stream2.getTracks());

  stream.onremovetrack = stream2.onremovetrack = t.step_func(() =>
    assert_unreached("onremovetrack is not triggered by script itself"));

  assert_equals(stream.getTracks().length, 2, "mediastream starts with 2 tracks");
  stream.removeTrack(stream.getVideoTracks()[0]);
  assert_equals(stream.getTracks().length, 1, "mediastream has 1 track left");
  stream.removeTrack(stream.getAudioTracks()[0]);
  assert_equals(stream.getTracks().length, 0, "mediastream has no tracks left");
  stream.removeTrack(stream2.getTracks()[0]); // should not throw

  // Allow time to verify no events fire.
  await new Promise(r => t.step_timeout(r, 1));

}, "Tests that a removal from a MediaStream works as expected");

async function doesEventFire(t, target, name, ms = 1) {
  const cookie = {};
  const value = await Promise.race([
    new Promise(r => target.addEventListener(name, r, {once: true})),
    new Promise(r => t.step_timeout(r, ms)).then(() => cookie)
  ]);
  return value !== cookie;
}

const doEventsFire = (t, target1, target2, name, ms = 1) => Promise.all([
  doesEventFire(t, target1, "ended", ms),
  doesEventFire(t, target2, "ended", ms)
]);

promise_test(async t => {
  const stream = await navigator.mediaDevices.getUserMedia({video: true, audio: true});
  const tracks = stream.getTracks();

  audio.srcObject = video.srcObject = stream;

  t.add_cleanup(() => {
    for (const track of tracks) {
      track.stop();
    }
    audio.srcObject = video.srcObject = null;
  });

  await Promise.all([
    new Promise(r => audio.onloadedmetadata = r),
    new Promise(r => video.onloadedmetadata = r)
  ]);

  assert_equals(audio.ended, false, "audio element starts out not ended");
  assert_equals(video.ended, false, "video element starts out not ended");

  stream.removeTrack(stream.getVideoTracks()[0]);
  {
    const [audioDidEnd, videoDidEnd] = await doEventsFire(t, audio, video, "ended");
    assert_equals(audio.ended, false, "audio element unaffected");
    assert_equals(audioDidEnd, false, "no audio ended event should fire yet");
    assert_equals(video.ended, false, "video element keeps going with audio track");
    assert_equals(videoDidEnd, false, "no video ended event should fire yet");
  }
  stream.removeTrack(stream.getAudioTracks()[0]);
  {
    const [audioDidEnd, videoDidEnd] = await doEventsFire(t, audio, video, "ended");
    assert_equals(audio.ended, true, "audio element ended because no more audio tracks");
    assert_equals(audioDidEnd, true, "go audio ended event");
    assert_equals(video.ended, true, "video element ended because no more tracks");
    assert_equals(videoDidEnd, true, "got video ended event");
  }
}, "Test that removal from a MediaStream fires ended on media elements (video first)");

promise_test(async t => {
  const stream = await navigator.mediaDevices.getUserMedia({video: true, audio: true});
  const tracks = stream.getTracks();

  audio.srcObject = video.srcObject = stream;

  t.add_cleanup(() => {
    for (const track of tracks) {
      track.stop();
    }
    audio.srcObject = video.srcObject = null;
  });

  await Promise.all([
    new Promise(r => audio.onloadedmetadata = r),
    new Promise(r => video.onloadedmetadata = r)
  ]);

  assert_equals(audio.ended, false, "audio element starts out not ended");
  assert_equals(video.ended, false, "video element starts out not ended");

  stream.removeTrack(stream.getAudioTracks()[0]);
  {
    const [audioDidEnd, videoDidEnd] = await doEventsFire(t, audio, video, "ended");
    assert_equals(audio.ended, true, "audio element ended because no more audio tracks");
    assert_equals(audioDidEnd, true, "got audio ended event");
    assert_equals(video.ended, false, "video element keeps going with video track");
    assert_equals(videoDidEnd, false, "no video ended event should fire yet");
  }
  stream.removeTrack(stream.getVideoTracks()[0]);
  {
    const [audioDidEnd, videoDidEnd] = await doEventsFire(t, audio, video, "ended");
    assert_equals(audio.ended, true, "audio element remains ended from before");
    assert_equals(audioDidEnd, false, "no second audio ended event should fire");
    assert_equals(video.ended, true, "video element ended because no more tracks");
    assert_equals(videoDidEnd, true, "got video ended event");
  }
}, "Test that removal from a MediaStream fires ended on media elements (audio first)");

</script>
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