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<title>RTCPeerConnection.prototype.ontrack</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="RTCPeerConnection-helper.js"></script>
<script>
  'use strict';

  // Test is based on the following editor draft:
  // https://w3c.github.io/webrtc-pc/archives/20170605/webrtc.html

  // The following helper functions are called from RTCPeerConnection-helper.js:
  //   getTrackFromUserMedia

  /*
    4.3.1.6.  Set the RTCSessionSessionDescription
      2.2.8.  If description is set as a remote description, then run the following
              steps for each media description in description:
        3.  Set transceiver's mid value to the mid of the corresponding media
            description. If the media description has no MID, and transceiver's
            mid is unset, generate a random value as described in [JSEP] (section 5.9.).
        4.  If the direction of the media description is sendrecv or sendonly, and
            transceiver.receiver.track has not yet been fired in a track event,
            process the remote track for the media description, given transceiver.

    5.1.1. Processing Remote MediaStreamTracks
      To process the remote track for an incoming media description [JSEP]
      (section 5.9.) given RTCRtpTransceiver transceiver, the user agent MUST
      run the following steps:

      1.  Let connection be the RTCPeerConnection object associated with transceiver.
      2.  Let streams be a list of MediaStream objects that the media description
          indicates the MediaStreamTrack belongs to.
      3.  Add track to all MediaStream objects in streams.
      4.  Queue a task to fire an event named track with transceiver, track, and
          streams at the connection object.

    5.7.  RTCTrackEvent
      [Constructor(DOMString type, RTCTrackEventInit eventInitDict)]
      interface RTCTrackEvent : Event {
        readonly attribute RTCRtpReceiver           receiver;
        readonly attribute MediaStreamTrack         track;
        [SameObject]
        readonly attribute FrozenArray<MediaStream> streams;
        readonly attribute RTCRtpTransceiver        transceiver;
      };

    [mediacapture-main]
    4.2.  MediaStream
      interface MediaStream : EventTarget {
        readonly attribute DOMString    id;
        sequence<MediaStreamTrack> getTracks();
        ...
      };

    [mediacapture-main]
    4.3.  MediaStreamTrack
      interface MediaStreamTrack : EventTarget {
        readonly attribute DOMString             kind;
        readonly attribute DOMString             id;
        ...
      };
   */

  function validateTrackEvent(trackEvent) {
    const { receiver, track, streams, transceiver } = trackEvent;

    assert_true(track instanceof MediaStreamTrack,
      'Expect track to be instance of MediaStreamTrack');

    assert_true(Array.isArray(streams),
      'Expect streams to be an array');

    for(const mediaStream of streams) {
      assert_true(mediaStream instanceof MediaStream,
        'Expect elements in streams to be instance of MediaStream');

      assert_true(mediaStream.getTracks().includes(track),
        'Expect each mediaStream to have track as one of their tracks');
    }

    assert_true(receiver instanceof RTCRtpReceiver,
      'Expect trackEvent.receiver to be defined and is instance of RTCRtpReceiver');

    assert_equals(receiver.track, track,
      'Expect trackEvent.receiver.track to be the same as trackEvent.track');

    assert_true(transceiver instanceof RTCRtpTransceiver,
      'Expect trackEvent.transceiver to be defined and is instance of RTCRtpTransceiver');

    assert_equals(transceiver.receiver, receiver,
      'Expect trackEvent.transceiver.receiver to be the same as trackEvent.receiver');
  }

  // tests that ontrack is called and parses the msid information from the SDP and creates
  // the streams with matching identifiers.
  promise_test(async t => {
    const pc = new RTCPeerConnection();

    t.add_cleanup(() => pc.close());

    // Fail the test if the ontrack event handler is not implemented
    assert_idl_attribute(pc, 'ontrack', 'Expect pc to have ontrack event handler attribute');

    const sdp = `v=0
o=- 166855176514521964 2 IN IP4 127.0.0.1
s=-
t=0 0
a=msid-semantic:WMS *
m=audio 9 UDP/TLS/RTP/SAVPF 111
c=IN IP4 0.0.0.0
a=rtcp:9 IN IP4 0.0.0.0
a=ice-ufrag:someufrag
a=ice-pwd:somelongpwdwithenoughrandomness
a=fingerprint:sha-256 8C:71:B3:8D:A5:38:FD:8F:A4:2E:A2:65:6C:86:52:BC:E0:6E:94:F2:9F:7C:4D:B5:DF:AF:AA:6F:44:90:8D:F4
a=setup:actpass
a=rtcp-mux
a=mid:mid1
a=sendonly
a=rtpmap:111 opus/48000/2
a=msid:stream1 track1
a=ssrc:1001 cname:some
`;

    const trackEventPromise = addEventListenerPromise(t, pc, 'track');
    await pc.setRemoteDescription({ type: 'offer', sdp });
    const trackEvent = await trackEventPromise;
    const { streams, track, transceiver } = trackEvent;

    assert_equals(streams.length, 1,
      'the track belongs to one MediaStream');

    const [stream] = streams;
    assert_equals(stream.id, 'stream1',
      'Expect stream.id to be the same as specified in the a=msid line');

    assert_equals(track.kind, 'audio',
      'Expect track.kind to be audio');

    validateTrackEvent(trackEvent);

    assert_equals(transceiver.direction, 'recvonly',
      'Expect transceiver.direction to be reverse of sendonly (recvonly)');
  }, 'setRemoteDescription should trigger ontrack event when the MSID of the stream is is parsed.');

  promise_test(async t => {
    const pc = new RTCPeerConnection();

    t.add_cleanup(() => pc.close());

    assert_idl_attribute(pc, 'ontrack', 'Expect pc to have ontrack event handler attribute');

    const sdp = `v=0
o=- 166855176514521964 2 IN IP4 127.0.0.1
s=-
t=0 0
a=msid-semantic:WMS *
m=audio 9 UDP/TLS/RTP/SAVPF 111
c=IN IP4 0.0.0.0
a=rtcp:9 IN IP4 0.0.0.0
a=ice-ufrag:someufrag
a=ice-pwd:somelongpwdwithenoughrandomness
a=fingerprint:sha-256 8C:71:B3:8D:A5:38:FD:8F:A4:2E:A2:65:6C:86:52:BC:E0:6E:94:F2:9F:7C:4D:B5:DF:AF:AA:6F:44:90:8D:F4
a=setup:actpass
a=rtcp-mux
a=mid:mid1
a=recvonly
a=rtpmap:111 opus/48000/2
a=msid:stream1 track1
a=ssrc:1001 cname:some
`;

    pc.ontrack = t.unreached_func('ontrack event should not fire for track with recvonly direction');

    await pc.setRemoteDescription({ type: 'offer', sdp });
    await new Promise(resolve => t.step_timeout(resolve, 100));
  }, 'setRemoteDescription() with m= line of recvonly direction should not trigger track event');

  promise_test(async t => {
    const pc1 = new RTCPeerConnection();
    t.add_cleanup(() => pc1.close());
    const pc2 = new RTCPeerConnection();

    t.add_cleanup(() => pc2.close());

    const [track, mediaStream] = await getTrackFromUserMedia('audio');
    pc1.addTrack(track, mediaStream);
    const trackEventPromise = addEventListenerPromise(t, pc2, 'track');
    await pc2.setRemoteDescription(await pc1.createOffer());
    const trackEvent = await trackEventPromise;

    assert_equals(trackEvent.track.kind, 'audio',
      'Expect track.kind to be audio');

    validateTrackEvent(trackEvent);
  }, 'addTrack() should cause remote connection to fire ontrack when setRemoteDescription()');

  promise_test(async t => {
    const pc1 = new RTCPeerConnection();
    t.add_cleanup(() => pc1.close());
    const pc2 = new RTCPeerConnection();

    t.add_cleanup(() => pc2.close());

    pc1.addTransceiver('video');

    const trackEventPromise = addEventListenerPromise(t, pc2, 'track');
    await pc2.setRemoteDescription(await pc1.createOffer());
    const trackEvent = await trackEventPromise;
    const { track } = trackEvent;

    assert_equals(track.kind, 'video',
      'Expect track.kind to be video');

    validateTrackEvent(trackEvent);
  }, `addTransceiver('video') should cause remote connection to fire ontrack when setRemoteDescription()`);

  promise_test(async t => {
    const pc1 = new RTCPeerConnection();
    t.add_cleanup(() => pc1.close());
    const pc2 = new RTCPeerConnection();

    t.add_cleanup(() => pc2.close());

    pc1.addTransceiver('audio', { direction: 'inactive' });
    pc2.ontrack = t.unreached_func('ontrack event should not fire for track with inactive direction');

    await pc2.setRemoteDescription(await pc1.createOffer());
    await new Promise(resolve => t.step_timeout(resolve, 100));
  }, `addTransceiver() with inactive direction should not cause remote connection to fire ontrack when setRemoteDescription()`);

  ["audio", "video"].forEach(type => promise_test(async t => {
    const pc1 = new RTCPeerConnection();
    t.add_cleanup(() => pc1.close());
    const pc2 = new RTCPeerConnection();
    t.add_cleanup(() => pc2.close());

    const checkNoUnexpectedTrack = ({track}) => {
      assert_equals(track.kind, type, `ontrack event should not fire for ${track.kind}`);
    };

    pc2.ontrack = t.step_func(checkNoUnexpectedTrack);
    pc1.ontrack = t.step_func(checkNoUnexpectedTrack);

    await pc1.setLocalDescription(await pc1.createOffer(
      { offerToReceiveVideo: true, offerToReceiveAudio: true }));

    pc2.addTrack(...await getTrackFromUserMedia(type));

    await pc2.setRemoteDescription(pc1.localDescription);
    await pc2.setLocalDescription(await pc2.createAnswer());
    await pc1.setRemoteDescription(pc2.localDescription);

    await new Promise(resolve => t.step_timeout(resolve, 100));
  }, `Using offerToReceiveAudio and offerToReceiveVideo should only cause a ${type} track event to fire, if ${type} was the only type negotiated`));

</script>