chromium/third_party/blink/web_tests/accessibility/css-first-letter-children.html

<!DOCTYPE html>
<script src="../resources/testharness.js"></script>
<script src="../resources/testharnessreport.js"></script>
<style>
p::first-letter {
  font-size: 200%;
}
</style>
<h1 id="heading">Test heading</h1>
<p id="text">Test text</p>
<script>
test(function () {
  if (!window.accessibilityController) {
    assert_unreached("This test requires accessibilityController.");
    return;
  }

  // Test an element that gets its own accessible name.
  let element = accessibilityController.accessibleElementById("heading");
  assert_equals(element.name, "Test heading");

  function getAccessibilityChildren(element) {
    let children = [];
    let childrenCount = element.childrenCount;
    for (let i = 0; i < childrenCount; i++) {
      let child = element.childAtIndex(i);
      children.push(child);
    }
    return children;
  }

  // Test by concatenating names of all children.
  element = accessibilityController.accessibleElementById("text");
  let children = getAccessibilityChildren(element);
  assert_equals(children.length, 1);
  let name = children.map(e => e.name).join('');
  assert_equals(name, "Test text");
});
</script>