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<title>RTCPeerConnection-remote-track-currentTime.https.html</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="RTCPeerConnection-helper.js"></script>
<script>
'use strict';

/*
 * This test is checking the below spec text for MediaStreamTracks received
 * through an RTCPeerConnection.
 *
 * § 6. MediaStreams in Media Elements
 *
 *   A MediaStream (...) represents a simple, potentially infinite, linear media
 *   timeline. The timeline starts at 0 and increments linearly in real time as
 *   long as the media element is potentially playing. The timeline does not
 *   increment when the playout of the MediaStream is paused.
 */

async function setupPeerConnectionAndWaitForTrack(t, kind) {
  const pc1 = createPeerConnectionWithCleanup(t);
  pc1.addTrack(... await createTrackAndStreamWithCleanup(t, "video"));
  const pc2 = createPeerConnectionWithCleanup(t);
  exchangeIceCandidates(pc1, pc2);

  const haveTrack = waitUntilEvent(pc2, "track");
  await exchangeOfferAnswer(pc1, pc2);
  const {track} = await haveTrack;
  return {pc1, pc2, track};
}

async function setupMediaElementAndCheckInitialCurrentTime(t, track) {
  const elem = document.createElement(track.kind);
  elem.srcObject = new MediaStream([track]);
  assert_equals(elem.currentTime, 0, "currentTime starts at 0");
  elem.play();
  await new Promise(r => elem.ontimeupdate = r);
  assert_between_exclusive(elem.currentTime, 0, 0.5,
    "currentTime starts at 0 and has progressed at first timeupdate"
  );
  assert_equals(elem.readyState, elem.HAVE_ENOUGH_DATA,
    "Media element has enough data once currentTime is progressing"
  );
  return elem;
}

async function checkCurrentTimeProgressing(t, elem) {
  const currentTime1 = elem.currentTime;
  // Note that when `currentTime1` was updated by the UA, it dispatched a task
  // to fire a "timeupdate" event (per the "time marches on" algorithm in the
  // spec). This event may not have fired yet, which is why we must wait for two
  // such events.
  try {
    await Promise.race([
      (async () =>
       {
         await waitUntilEvent(elem, "timeupdate");
         await waitUntilEvent(elem, "timeupdate");
       }
      )(),
      new Promise((res, rej) => t.step_timeout(rej, 3000)),
    ]);
  } catch(e) {
    assert_unreached("Timed out waiting for timeupdate");
  }
  assert_greater_than(elem.currentTime, currentTime1);
}

async function setSenderActive(t, sender, active) {
  const parameters = sender.getParameters();
  parameters.encodings[0].active = active;
  await sender.setParameters(parameters);
  // Wait a bit longer to be certain the parameter changes have propagated to
  // the receiver.
  await new Promise(r => t.step_timeout(r, 100));
}

promise_test(async t => {
  const {track} = await setupPeerConnectionAndWaitForTrack(t, "audio");
  const elem = await setupMediaElementAndCheckInitialCurrentTime(t, track);
  await checkCurrentTimeProgressing(t, elem);
}, 'currentTime advances for receive audio track of active sender');

promise_test(async t => {
  const {track} = await setupPeerConnectionAndWaitForTrack(t, "video");
  const elem = await setupMediaElementAndCheckInitialCurrentTime(t, track);
  await checkCurrentTimeProgressing(t, elem);
}, 'currentTime advances for receive video track of active sender');

promise_test(async t => {
  const {pc1, track} = await setupPeerConnectionAndWaitForTrack(t, "audio");
  const elem = await setupMediaElementAndCheckInitialCurrentTime(t, track);
  await setSenderActive(t, pc1.getSenders()[0], false);
  await checkCurrentTimeProgressing(t, elem);
}, 'currentTime advances for receive audio track of inactive sender');

promise_test(async t => {
  const {pc1, track} = await setupPeerConnectionAndWaitForTrack(t, "video");
  const elem = await setupMediaElementAndCheckInitialCurrentTime(t, track);
  await setSenderActive(t, pc1.getSenders()[0], false);
  await checkCurrentTimeProgressing(t, elem);
}, 'currentTime advances for receive video track of inactive sender');

</script>