transition-after-animation-001.html

<!DOCTYPE html>
<title>Starting transition after animation has ended</title>
<link rel="help" href="https://drafts.csswg.org/css-transitions/">
<link rel="help" href="https://crbug.com/1261155">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="./support/helper.js"></script>
<style>
  @keyframes anim {
    from { left: 100px }
    to { left: 200px }
  }
  #div {
    left: 0px;
    position: relative;
    width: 50px;
    height: 50px;
    background-color: green;
  }
  #div.animate {
    animation: anim 0.1s linear;
  }
  #div.transition {
    left: 300px;
    transition: left 1000s steps(2, start);
  }
</style>
<div id=div>
</div>
<script>

promise_test(async t => {
    const watcher = new EventWatcher(t, div, ['animationend']);

    assert_equals(getComputedStyle(div).left, '0px');

    div.classList.toggle('animate');
    assert_equals(getComputedStyle(div).left, '100px');

    await watcher.wait_for('animationend');
    assert_equals(getComputedStyle(div).left, '0px');

    div.classList.toggle('transition');
    assert_equals(getComputedStyle(div).left, '150px');
}, 'Starting transition after animation has ended');

</script>

chromium/third_party/blink/web_tests/external/wpt/css/css-transitions/transition-after-animation-001.html