template-shadowroot-reflection.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>Template shadowRoot reflection</title>
<script src='../resources/testharness.js'></script>
<script src='../resources/testharnessreport.js'></script>

<!-- This simply tests whether HTMLTemplateElement has a `shadowRoot` attribute.
  It should not, since that was deprecated and removed as part of the original
  declarative Shadow DOM. -->

<script>
  test(() => {
    assert_false(HTMLTemplateElement.prototype.hasOwnProperty("shadowRoot"));
  }, "HTMLTemplateElement should not have a shadowRoot own property");
</script>

chromium/third_party/blink/web_tests/shadow-dom/template-shadowroot-reflection.html