chromium/third_party/blink/web_tests/external/wpt/media-source/dedicated-worker/mediasource-worker-play-terminate-worker.html

<!DOCTYPE html>
<html>
<title>MediaSource-in-Worker looped playback test case with worker termination at various places</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="mediasource-message-util.js"></script>
<body>
<script>

function terminateWorkerAfterMultipleSetTimeouts(video, test, worker, timeouts_remaining) {
  if (timeouts_remaining <= 0) {
    // Terminating the worker may introduce errors in the video element we don't care about.
    video.onerror = null;
    worker.terminate();
    test.step_timeout(() => { test.done(); }, 0);
  } else {
    test.step_timeout(() => {
      terminateWorkerAfterMultipleSetTimeouts(video, test, worker, --timeouts_remaining);
    }, 0);
  }
}

function startWorkerAndTerminateWorker(test, when_to_start_timeouts, timeouts_to_await) {
  // Fail fast if MSE-in-Workers is not supported.
  assert_true(MediaSource.hasOwnProperty("canConstructInDedicatedWorker"), "MediaSource hasOwnProperty 'canConstructInDedicatedWorker'");
  assert_true(MediaSource.canConstructInDedicatedWorker, "MediaSource.canConstructInDedicatedWorker");

  const worker = new Worker("mediasource-worker-play-terminate-worker.js");
  worker.onerror = test.unreached_func("worker error");

  const video = document.createElement("video");
  document.body.appendChild(video);
  video.onerror = _ => {
    assert_unreached(
        `video element error: \"${video.error.message}\": ${video.error.code}`);
  }

  if (when_to_start_timeouts == "after first ended event") {
    video.addEventListener("ended", test.step_func(() => {
      terminateWorkerAfterMultipleSetTimeouts(video, test, worker, timeouts_to_await);
      video.currentTime = 0;
      video.loop = true;
    }), { once : true });
  } else {
    video.loop = true;
  }

  if (when_to_start_timeouts == "before setting srcObject") {
    terminateWorkerAfterMultipleSetTimeouts(video, test, worker, timeouts_to_await);
  }

  worker.onmessage = test.step_func(e => {
    let subject = e.data.subject;
    assert_true(subject != undefined, "message must have a subject field");
    switch (subject) {
      case messageSubject.ERROR:
        assert_unreached("Worker error: " + e.data.info);
        break;
      case messageSubject.HANDLE:
        const handle = e.data.info;
        video.srcObject = handle;
        if (when_to_start_timeouts == "after setting srcObject") {
          terminateWorkerAfterMultipleSetTimeouts(video, test, worker, timeouts_to_await);
        }
        video.play().catch(error => {
          // Only rejections due to MEDIA_ERR_SRC_NOT_SUPPORTED are expected to possibly
          // occur, except if we expect to reach at least 1 'ended' event.
          assert_not_equals(when_to_start_timeouts, "after first ended event");
          assert_true(video.error != null);
          assert_equals(video.error.code, MediaError.MEDIA_ERR_SRC_NOT_SUPPORTED);
          // Do not rethrow. Instead, wait for the step_timeouts to finish the test.
        });
        break;
      default:
        assert_unreached("Unexpected message subject: " + subject);
    }
  });
}

[ "before setting srcObject", "after setting srcObject", "after first ended event" ].forEach(when => {
  for (let timeouts = 0; timeouts < 10; ++timeouts) {
    async_test(test => { startWorkerAndTerminateWorker(test, when, timeouts); },
        "Test worker MediaSource termination after at least " + timeouts +
          " main thread setTimeouts, starting counting " + when);
  }
});

</script>
</body>
</html>