enumerateDevices-in-background.https.html

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This WPT test may be referenced by the following Test IDs:
- /mediacapture-streams/enumerateDevices-in-background.https.html - WPT Dashboard Interop Dashboard

<!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>