chromium/third_party/blink/web_tests/media/controls/volume-slider-controlled-by-scroll.html

<!DOCTYPE html>
<title>media controls volume slider should be controlled by scrolling</title>
<script src="../../resources/gesture-util.js"></script>
<script src="../../resources/testharness.js"></script>
<script src="../../resources/testharnessreport.js"></script>
<script src="../media-controls.js"></script>
<body></body>
<script>
// Ensure that we will show the volume slider.
internals.settings.setPreferHiddenVolumeControls(false);

var video = document.createElement('video');
var videoWithAudio = document.createElement('video');
var audio = document.createElement('audio');

const testElements = [video, videoWithAudio, audio];
let currentTest = 0;

testElements.forEach(element => {
  element.controls = true;
  element.preload = 'none';
});

video.id = 'video';
videoWithAudio.id = 'video-with-audio';
audio.id = 'audio';

video.src = '../content/test.webm'
videoWithAudio.src = '../content/test.oga';
audio.src = '../content/test.oga';


async_test(function(t) {
  runNextTest(t);
});

// Need to run each test synchronously to avoid the race conditions causing the
// slider to open/close.
function runNextTest(t) {
  if (currentTest == testElements.length) {
    t.done();
  }

  const testElement = testElements[currentTest];
  currentTest++;

  document.body.append(testElement);
  testMediaElement(t, testElement);
}

function testMediaElement(t, element) {
  const muteBtn = muteButton(element);
  const volumeSlider = volumeSliderElement(element);
  const currentTime = currentTimeElement(element);

  element.onloadedmetadata = t.step_func(function() {
    // Hovering over the mute button after preloading should open the volume
    // slider.
    hoverMuteButton(element, t.step_func(() => {
      assert_true(isVolumeSliderOpen(element), element.id + ': volume slider should open when hovering the mute button');
      assert_equals(element.volume, 1, element.id + ': volume should start at 1');

      wheelTick(0, 20, elementCenter(muteBtn)).then(t.step_func(() => {
        assert_less_than(element.volume, 1, element.id + ': volume should change when scrolling on the mute button');

        wheelTick(0, -30, elementCenter(volumeSlider)).then(t.step_func(() => {
          assert_equals(element.volume, 1, element.id + ': volume should change when scrolling on the volume slider');
          runNextTest(t);
        }));
      }));
    }));
  });

  element.load();
}
</script>