chromium/third_party/blink/web_tests/external/wpt/css/css-flexbox/flexbox_first-letter.html

<!DOCTYPE html>
<title>flexbox | first-letter</title>
<meta name="assert" content="This test is ensures that flexbox placement does not apply to ::first-letter psuedo-content">
<link rel="author" title="Vince Falconi" href="[email protected]">
<link rel="help" href="https://drafts.csswg.org/css-flexbox-1/#placement">
<style>
  div { display: flex; }
  div::first-letter { order: 2 }
</style>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>

<div>Triceratops</div>

<script>
  test(function() {
    let order = getComputedStyle(document.querySelector('div'), '::first-letter').order;
    assert_not_equals(order, '2');
  });
</script>