test_getCoalescedEvents_retained_event_leak.html

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<html>

<!--

https://bugzilla.mozilla.org/show_bug.cgi?id=2076389

-->

<head>

  <meta charset="utf-8">

  <title>Test that a retained pointermove event with coalesced events does not keep its document alive</title>

  <script src="/tests/SimpleTest/EventUtils.js"></script>

  <script src="/tests/SimpleTest/SimpleTest.js"></script>

  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>

</head>

<body>

<script type="text/javascript">

/** Test for Bug 2076389 */

SimpleTest.waitForExplicitFinish();

// Loads a same-origin iframe whose "pointermove" listener calls

// getCoalescedEvents() and retains the event object.

async function loadFrame() {

  const frame = document.createElement("iframe");

  frame.style = "width: 200px; height: 100px; border: 0";

  frame.src = "file_getCoalescedEvents_retained_event_leak.html";

  document.body.appendChild(frame);

  await new Promise(resolve => (frame.onload = resolve));

  return frame;

SimpleTest.waitForFocus(async () => {

  let frame = await loadFrame();

  // The first synthesized mouse move into the iframe only generates the

  // boundary events, so keep moving until the iframe has seen a pointermove.

  let x = 50;

  await SimpleTest.promiseWaitForCondition(() => {

    synthesizeMouse(frame, x++, 30, { type: "mousemove" });

    return frame.contentWindow.events.length >= 1;

  }, "Waiting for a pointermove event to be dispatched into the iframe");

  ok(frame.contentWindow.events.length >= 1,

     "The pointermove event should have been dispatched and retained");

  ok(frame.contentWindow.coalescedEventCount >= 1,

     "getCoalescedEvents() should have returned at least one event");

  const weakWindow = SpecialPowers.Cu.getWeakReference(frame.contentWindow);

  const weakDocument = SpecialPowers.Cu.getWeakReference(frame.contentDocument);

  ok(weakWindow.get(), "Should be able to create a weak reference to the window");

  ok(weakDocument.get(), "Should be able to create a weak reference to the document");

  frame.remove();

  frame = null;

  // Move the mouse away so that the removed frame is not the last hovered

  // content anymore.

  synthesizeMouseAtCenter(document.body, { type: "mousemove" });

  // Perform many GCs to avoid intermittent delayed collection, spinning the

  // event loop between attempts.

  for (let i = 0; i < 10 && (weakWindow.get() || weakDocument.get()); i++) {

    await new Promise(resolve => SimpleTest.executeSoon(resolve));

    await new Promise(resolve => SpecialPowers.exactGC(resolve));

  ok(!weakWindow.get(),

     "The iframe's window should be collected after the frame is removed");

  ok(!weakDocument.get(),

     "The iframe's document should be collected after the frame is removed");

  SimpleTest.finish();

});

</script>

</body>

</html>