chromium/third_party/blink/web_tests/fast/frames/unique-name-ancestor-concatenation-conflict.html

<!DOCTYPE html>
<!--
This test highlights that the old unique name generation algorithm
could generate non-unique names even for static-html pages (i.e. with
no renames and with no removal or addition of frames via DOM).

This test would fail before FrameTree.cpp changes in
https://crrev.com/1968213002.
  -->
<html>
<script>
if (window.testRunner) {
    testRunner.dumpAsText();
    testRunner.dumpChildFrames();
}
</script>
<body>

<iframe name="foo" srcdoc="
  <iframe name='bar' srcdoc='
    <iframe></iframe>
    <iframe></iframe>
    <iframe></iframe>
  '></iframe>
"></iframe>

<iframe name="foo/bar" srcdoc="
    <iframe></iframe>
    <iframe></iframe>
    <iframe></iframe>
"></iframe>

</body>
</html>