<!doctype html>
<title>enumerateDevices() in background tab with focus in chrome</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>
<body></body>
<script>
'use strict';
// This test is not in cross-browser wpt because it uses Gecko-specific API
// for focusing browser chrome and it assumes a specific tab browser design.
// It assumes that
// * browser chrome widget focus is associated with a single current document
//   presentation (tab),
//   https://github.com/w3c/mediacapture-main/issues/752#issuecomment-742036800
// * window.open() focuses the new tab and makes the current tab hidden, and
// * the opener tab becomes the current and visible tab again when the new tab
//   is closed.
const blank_url = '/common/blank.html';

function promise_event(target, name) {
  return new Promise(resolve => target[`on${name}`] = resolve);
}

promise_test(async t => {
  // Open a new tab, which is expected to receive focus and hide the first tab.
  await test_driver.bless('window.open()');
  assert_true(document.hasFocus(), 'This test needs focus on the browser.');
  const promise_hidden = promise_event(document, 'visibilitychange');
  const proxy = window.open(blank_url);
  t.add_cleanup(() => proxy.close());
  await Promise.all([
    promise_hidden,
    promise_event(proxy, 'focus'),
    promise_event(proxy, 'load'),
  ]);
  assert_true(proxy.document.hasFocus(), 'proxy.document.hasFocus()');

  await Promise.all([
    promise_event(proxy, 'blur'),
    SpecialPowers.spawnChrome([], function focus_url_bar() {
      this.browsingContext.topChromeWindow.gURLBar.focus();
    }),
  ]);
  assert_false(proxy.document.hasFocus(), 'proxy.document.hasFocus()');
  assert_false(document.hasFocus(), 'document.hasFocus()');
  assert_equals(document.visibilityState, 'hidden', 'visibilityState');

  // Enumeration should remain pending while the first tab is background.
  const promise_enumerate = navigator.mediaDevices.enumerateDevices();
  // Enumerate in the foreground tab to confirm that URL bar focus is
  // sufficient, and to provide enough time to check that the Promise from the
  // background tab does not settle.
  await proxy.navigator.mediaDevices.enumerateDevices();
  // Race a settled Promise to check that the enumeration in the background tab
  // has not settled.
  const result = await Promise.race([promise_enumerate, 'pending']);
  assert_equals(result, 'pending', 'pending Promise while background.');

  // The enumeration Promise should resolve after the first tab returns to the
  // foreground.
  proxy.close();
  await promise_event(document, 'visibilitychange');
  assert_equals(document.visibilityState, 'visible', 'visibilityState');
  await promise_enumerate;
}, 'enumerateDevices in background');
</script>
