<!DOCTYPE html>
<html>
<head>
  <title>Discard a new BrowsingContext during window.open nested event loop</title>
  <script src="/tests/SimpleTest/SimpleTest.js"></script>
  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
</head>
<body>
<script>
add_task(async function() {
  const TOPIC = "dangerous:test-only:new-browser-child-ready";

  let found = false;
  function observer(subject, topic, data) {
    let win = SpecialPowers.wrap(subject);
    if (SpecialPowers.compare(win.opener, window)) {
      found = true;
      SpecialPowers.removeObserver(observer, TOPIC);

      win.close();
      // window.close() is not synchronous, so we need to wait for the
      // BrowsingContext to actually become discarded after we call it, to
      // make sure that the window provider actually has a discarded BC at the
      // end of its own nested event loop.
      SpecialPowers.Services.tm.spinEventLoopUntil(
        "Test(test_window_open_discarded_bc.html:add_task)",
        () => !win.opener
      );
    }
  }
  SpecialPowers.addObserver(observer, TOPIC);

  let win = window.open();

  is(found, true, "Our observer should have fired for the new window");
  is(win, null, "window.open() should return null when new window is already closed");
});
</script>
</body>
</html>
