<!doctype html>
<meta charset=utf-8>
<title>DocumentTimeline interface: style change events</title>
<link rel="help"
      href="https://drafts.csswg.org/web-animations-1/#model-liveness">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="../../testcommon.js"></script>
<body>
<div id="log"></div>
<script>
'use strict';

// NOTE: If more members are added to the DocumentTimeline interface it might be
// better to rewrite these test in the same style as:
//
//  web-animations/interfaces/Animation/style-change-events.html
//  web-animations/interfaces/KeyframeEffect/style-change-events.html

promise_test(async t => {
  const div = createDiv(t);

  let gotTransition = false;
  div.addEventListener('transitionrun', () => {
    gotTransition = true;
  });

  // Create a covering animation but don't play it yet.
  const coveringAnimation = new Animation(
    new KeyframeEffect(div, { opacity: [0, 1] }, 100 * MS_PER_SEC)
  );

  // Setup transition start point.
  div.style.transition = 'opacity 100s';
  getComputedStyle(div).opacity;

  // Update specified style but don't flush style.
  div.style.opacity = '0.5';

  // Get the currentTime
  document.timeline.currentTime;

  // Run the covering animation
  coveringAnimation.play();

  // If getting DocumentTimeline.currentTime produced a style change event it
  // will trigger a transition. Otherwise, the covering animation will cause
  // the before-change and after-change styles to be the same such that no
  // transition is triggered on the next restyle.

  // Wait for a couple of animation frames to give the transitionrun event
  // a chance to be dispatched.
  await waitForAnimationFrames(2);

  assert_false(gotTransition, 'A transition should NOT have been triggered');
}, 'DocumentTimeline.currentTime does NOT trigger a style change event');

promise_test(async t => {
  const div = createDiv(t);

  let gotTransition = false;
  div.addEventListener('transitionrun', () => {
    gotTransition = true;
  });

  // Create a covering animation but don't play it yet.
  const coveringAnimation = new Animation(
    new KeyframeEffect(div, { opacity: [0, 1] }, 100 * MS_PER_SEC)
  );

  // Setup transition start point.
  div.style.transition = 'opacity 100s';
  getComputedStyle(div).opacity;

  // Update specified style but don't flush style.
  div.style.opacity = '0.5';

  // Create a new DocumentTimeline
  new DocumentTimeline();

  // Run the covering animation
  coveringAnimation.play();

  // Wait for a couple of animation frames to give the transitionrun event
  // a chance to be dispatched.
  await waitForAnimationFrames(2);

  assert_false(gotTransition, 'A transition should NOT have been triggered');
}, 'DocumentTimeline constructor does NOT trigger a style change event');

</script>
</body>
