Node-appendChild-script-with-mutation-observer-takeRecords.html

<!DOCTYPE html>
<meta charset=utf-8>
<title>Node.appendChild: inserted script should be able to take own mutation record</title>
<script src=/resources/testharness.js></script>
<script src=/resources/testharnessreport.js></script>
<body>
<main></main>
<script>

test(() => {
  window.mutationObserver = new MutationObserver(() => {});
  window.mutationObserver.observe(document.querySelector("main"), {childList: true});
  const script = document.createElement("script");
  script.textContent = `
    window.mutationRecords = window.mutationObserver.takeRecords();
  `;
  document.querySelector("main").appendChild(script);
  assert_equals(window.mutationRecords.length, 1);
  assert_array_equals(window.mutationRecords[0].addedNodes, [script]);
}, "An inserted script should be able to observe its own mutation record with takeRecords");
</script>

chromium/third_party/blink/web_tests/external/wpt/dom/nodes/insertion-removing-steps/Node-appendChild-script-with-mutation-observer-takeRecords.html