mutation-observer.html

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This test has a WPT meta file that expects 2 subtest issues.
This WPT test may be referenced by the following Test IDs:
- /dom/nodes/moveBefore/tentative/mutation-observer.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<title>slotchanged event</title>

<script src="/resources/testharness.js"></script>

<script src="/resources/testharnessreport.js"></script>

<body>

<div id=oldParent>

  <p id=target></p>

</div>

<div id=newParent></div>

<script>

async function runTest(oldParent, target, newParent) {

  const observations = [];

  const observer = new MutationObserver(mutationList => observations.push(mutationList));

  observer.observe(oldParent, {childList: true});

  observer.observe(target, {childList: true});

  observer.observe(newParent, {childList: true});

  newParent.moveBefore(target, null);

  // Wait for microtasks to settle.

  await new Promise(resolve => queueMicrotask(resolve));

  assert_equals(observations.length, 1, "MutationObserver has emitted a single mutation list");

  assert_equals(observations[0].length, 2, "Mutation list has two MutationRecords");

  const removalRecord = observations[0][0];

  const insertionRecord = observations[0][1];

  assert_equals(removalRecord.target, oldParent, "removalRecord target is correct");

  assert_equals(removalRecord.removedNodes[0], target, "removedNodes contains the moved node");

  assert_equals(insertionRecord.target, newParent, "insertionRecord target is correct");

  assert_equals(insertionRecord.addedNodes[0], target, "addedNodes contains the moved node");

  observer.disconnect();

promise_test(async t => {

  await runTest(oldParent, target, newParent);

}, "[Connected move] MutationObserver removal + insertion is tracked by moveBefore()");

promise_test(async t => {

  const oldParent = document.createElement('div');

  const target = document.createElement('p');

  const newParent = document.createElement('div');

  // We must append `newParent` as well, since the origin and destination nodes

  // must share the same shadow-including root.

  oldParent.append(target, newParent);

  await runTest(oldParent, target, newParent);

}, "[Disconnected move] MutationObserver removal + insertion is tracked by moveBefore()");

</script>