chromium/third_party/blink/web_tests/external/wpt/css/css-flexbox/dynamic-isize-change-002.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS Flexbox Test: Dynamic change to the inline-size of a row flex container</title>
<link rel="author" title="Ting-Yu Lin" href="mailto:[email protected]">
<link rel="author" title="Mozilla" href="https://www.mozilla.org/">
<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1700580">
<link rel="match" href="../reference/ref-filled-green-100px-square.xht">
<meta name="assert" content="This test verifies that the dynamic change to the flex container's inline-size triggers the reflow for flex items with percentage padding.">

<style>
#flexbox {
  display: flex;
  inline-size: 50px;
  block-size: 100px;
  background: red;
}

#flexbox > div {
  box-sizing: border-box;

  /* The following flex-basis and padding will give our flex item a content-box
     inline-size of 25px, both before and after this test's dynamic change. */
  flex-basis: 100%;
  padding-right: calc(100% - 25px);
  background: green;
}
</style>

<p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
<div id="flexbox">
  <div></div>
</div>

<script>
/* Make sure the layout is up-to-date, which is essential to trigger the bug. */
document.documentElement.offsetHeight;

/* Change the flexbox's inline-size to trigger incremental reflow. */
document.getElementById("flexbox").style.inlineSize = "100px";
</script>