fullscreen/api/element-request-fullscreen-timing.html

<!DOCTYPE html>
<title>Element#requestFullscreen() timing</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/resources/testdriver.js"></script>
<script src="/resources/testdriver-vendor.js"></script>
<script src="../trusted-click.js"></script>
<div id="log"></div>
<script>
promise_test(async t => {
  const div = document.querySelector('div');

  // If fullscreenchange is an animation frame event, then animation frame
  // callbacks should be run after it is fired, before the timer callback.
  // The resize event should fire before the fullscreenchange event.
  const events = [];
  const p = new Promise(resolve => {
    const callback = t.step_func(event => {
      // fullscreenElement should have changed before either event is fired.
      assert_equals(document.fullscreenElement, div, `fullscreenElement in {event.type} event`);
      events.push(event.type);
      if (event.type == 'fullscreenchange') {
        step_timeout(t.unreached_func('timer callback'));
        requestAnimationFrame(t.step_func_done(() => {
          // Removed 'resize' expectation for now, see https://crbug.com/381127087.
          assert_array_equals(events, ['fullscreenchange'], 'event order');
          resolve();
        }));
      }
    });
    document.onfullscreenchange = window.onresize = callback;
  });
  await trusted_request(div);
  await p;
  // so the user doesn't have to exit for themselves
  document.exitFullscreen();
}, 'Timing of fullscreenchange and resize events');

async_test(t => {
  // Gecko throttles requestAnimationFrame before the first paint, so
  // wrap the test to work around that.
  requestAnimationFrame(t.step_func(() => {
    var promise = document.createElement('a').requestFullscreen();
    var promise_executed = false;
    promise.catch(()=>{promise_executed = true; });
    // If fullscreenerror is an animation frame event, then animation frame
    // callbacks should be run after it is fired, before the timer callback.
    document.onfullscreenerror = t.step_func(() => {
      assert_true(promise_executed, "promise executed");
      step_timeout(t.unreached_func('timer callback'));
      requestAnimationFrame(t.step_func_done());
    });
  }));
}, 'Timing of fullscreenerror event');
</script>