layout-instability/move-transformed.html

<!DOCTYPE html>
<title>Layout Instability: shift of a transformed container</title>
<link rel="help" href="https://wicg.github.io/layout-instability/" />
<style>
body { margin: 0; }
#transformed { position: relative; transform: translateX(20px); width: 100px; height: 100px; background: blue; }
</style>
<div id="transformed"></div>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/util.js"></script>
<script>

promise_test(async () => {
  const watcher = new ScoreWatcher;

  // Wait for the initial render to complete.
  await waitForAnimationFrames(2);

  document.querySelector("#transformed").style = "top: 50px";

  const expectedScore = computeExpectedScore(100 * (100 + 50), 50);

  await watcher.promise;
  assert_equals(watcher.score, expectedScore);
}, 'Move transformed container');

</script>