chromium/third_party/blink/web_tests/external/wpt/css/css-contain/content-visibility/content-visibility-050.html

<!doctype HTML>
<html>
<meta charset="utf8">
<title>Content Visibility: focus on new element</title>
<link rel="author" title="Rakina Zata Amni" href="mailto:[email protected]">
<link rel="help" href="https://drafts.csswg.org/css-contain/#content-visibility">
<meta name="assert" content="focus can target content-visibility: auto subtrees created while hidden">

<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>

<style>
.auto {
  content-visibility: auto;
}
.spacer {
  height: 3000px;
}
</style>

<div class=spacer></div>
<div id=container class=auto></div>

<script>
async_test((t) => {
  function runTest() {
    const focusable = document.createElement("div");
    focusable.tabIndex = 0;
    container.appendChild(focusable);
    focusable.focus();
    step_timeout(finish, 0);
  }
  function finish() {
    t.step(() => assert_greater_than(document.scrollingElement.scrollTop, 500));
    t.done();
  }
  onload = requestAnimationFrame(() => requestAnimationFrame(runTest));
}, "Using tabindex to focus an newly constructed element in an auto subtree focuses element");
</script>
</html>