chromium/third_party/blink/web_tests/http/tests/mediasession/media-control-action-reaches-client.html

<!DOCTYPE html>
<title>MediaSession Mojo Test</title>
<script src="../../../resources/testharness.js"></script>
<script src="../../../resources/testharnessreport.js"></script>
<script type="module">
import {MediaSessionServiceMock} from './resources/mediasessionservice-mock.js';
import {MediaSessionAction} from '/gen/services/media_session/public/mojom/media_session.mojom.m.js';

var mock;

var expectations = [
  "play",
  "pause",
  "previoustrack",
  "nexttrack",
  "seekbackward",
  "seekforward",
];

var nextExpectation = 0;

function checkExpectation(t, action, e) {
  assert_equals(e.action, action);

  var expectedEvent = expectations[nextExpectation];
  assert_equals(expectedEvent, action);
  if (++nextExpectation >= expectations.length)
    t.done();
}

function runTests(t) {
  window.navigator.mediaSession.setActionHandler(
      "play", t.step_func(checkExpectation.bind(null, t, "play")));
  window.navigator.mediaSession.setActionHandler(
      "pause", t.step_func(checkExpectation.bind(null, t, "pause")));
  window.navigator.mediaSession.setActionHandler(
      "previoustrack", t.step_func(checkExpectation.bind(null, t, "previoustrack")));
  window.navigator.mediaSession.setActionHandler(
      "nexttrack", t.step_func(checkExpectation.bind(null, t, "nexttrack")));
  window.navigator.mediaSession.setActionHandler(
      "seekbackward", t.step_func(checkExpectation.bind(null, t, "seekbackward")));
  window.navigator.mediaSession.setActionHandler(
      "seekforward", t.step_func(checkExpectation.bind(null, t, "seekforward")));

  mock.getClient().didReceiveAction(MediaSessionAction.kPlay);
  mock.getClient().didReceiveAction(MediaSessionAction.kPause);
  mock.getClient().didReceiveAction(MediaSessionAction.kPreviousTrack);
  mock.getClient().didReceiveAction(MediaSessionAction.kNextTrack);
  mock.getClient().didReceiveAction(MediaSessionAction.kSeekBackward);
  mock.getClient().didReceiveAction(MediaSessionAction.kSeekForward);
}

// Use async_test to do asynchronous setup since setup() only works for
// synchronous setup.
async_test(function(t) {
  mock = new MediaSessionServiceMock();
  mock.setClientCallback(t.step_func(runTests.bind(null, t)));
  // Touch window.navigator.mediaSession to start the service.
  window.navigator.mediaSession.metadata = null;
}, "test that the mock service is setup");

</script>