fullscreen/api/fullscreen-reordering.html

<!DOCTYPE html>
<title>Re-requesting fullscreen doesn't fail but doesn't change order</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/resources/testdriver.js"></script>
<script src="/resources/testdriver-vendor.js"></script>
<script src="/common/top-layer.js"></script>

<div class="elements">
  <div id="A">Element A</div>
  <div id="B">Element B</div>
</div>

<style>
  .elements > div {
    width: 200px;
    height: 200px;
  }
  #A { background: blue; }
  #B { background: green; }
</style>

<script>
promise_test(async (t) => {
  t.add_cleanup(async () => {
    while (document.fullscreenElement)
      await document.exitFullscreen();
  });
  document.onfullscreenerror = () => assert_unreached('fullscreenerror should not happen');
  const A = document.getElementById('A');
  const B = document.getElementById('B');
  assert_true(!isTopLayer(A) && !isTopLayer(B));
  await blessTopLayer(document.body);
  await A.requestFullscreen();
  assert_equals(document.fullscreenElement, A, 'first A request');
  assert_true(isTopLayer(A), 'A top layer');
  await blessTopLayer(A);
  try {
    await B.requestFullscreen();
  } catch (error) {
    assert_unreached('The second call to requestFullscreen rejected - it should be possible to put siblings into fullscreen together');
  }
  assert_equals(document.fullscreenElement, B, 'B request');
  assert_true(isTopLayer(B), 'B top layer');
  assert_true(isTopLayer(A), 'A still top layer');
  await blessTopLayer(B);
  await A.requestFullscreen();
  assert_true(isTopLayer(A), 'A is still top layer');
  assert_true(isTopLayer(B), 'B is still top layer');
  assert_equals(document.fullscreenElement, A, 'A is moved back to the top of the top layer stack');
  assert_equals(document.elementFromPoint(10, 10), A, 'A should be topmost');

  await document.exitFullscreen();
  assert_equals(document.fullscreenElement, B, 'B goes back to being the fullscreen element');
  assert_true(isTopLayer(B), 'B is still top layer');
  assert_false(isTopLayer(A), 'A is no longer top layer');
  await document.exitFullscreen();
  assert_equals(document.fullscreenElement, null, 'Both closed');
  assert_false(isTopLayer(A), 'A is no longer top layer');
  assert_false(isTopLayer(B), 'B is no longer top layer');
}, 'Requesting fullscreen on A, then B, then A');
</script>