enumerateDevices-with-navigation.https.html

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

<!doctype html>

<title>enumerateDevices() with navigation</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';

const blank_url = '/common/blank.html';

const search2 = '?2';

function promise_new_task(t) {

  return new Promise(resolve => t.step_timeout(resolve, 0));

function promise_event(target, name) {

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

promise_test(async t => {

  // Gecko persists only toplevel documents, so load documents in a toplevel.

  await test_driver.bless('window.open()');

  const proxy = window.open(blank_url);

  t.add_cleanup(() => proxy.close());

  await promise_event(proxy, 'pageshow');

  const devices = proxy.navigator.mediaDevices;

  // Use another task so that another load creates a new session history entry.

  await promise_new_task(t);

  proxy.location = blank_url + search2;

  await promise_event(proxy, 'pagehide');

  // Use another task to ensure the first subdocument is no longer fully

  // active and proxy refers to the realm of the second document.

  await promise_new_task(t);

  assert_equals(proxy.location.search, search2, 'navigated search');

  // Enumerate from the inactive first Window.

  const promise_enumerate = devices.enumerateDevices();

  // `then()` is used rather than static Promise methods because microtasks

  // for `PromiseResolve()` do not run when Promises from inactive realms are

  // involved.  Whether microtasks for `then()` run depends on the realm of

  // the handler rather than the realm of the Promise.

  // Don't use `finally()`, because it uses `PromiseResolve()` and so

  // microtasks don't run.

  // See https://github.com/whatwg/html/issues/5319.

  let promise_state = 'pending';

  promise_enumerate.then(() => promise_state = 'resolved',

                         () => promise_state = 'rejected');

  // Enumerate in the active second Window to provide enough time to check

  // that the Promise from the inactive Window does not settle.

  await proxy.navigator.mediaDevices.enumerateDevices();

  proxy.history.back();

  await promise_event(proxy, 'pagehide');

  // enumerateDevices() Promise resolution is triggered only in parallel

  // steps, so manipulation of the Promise (if the first document was

  // persisted) would occur through a queued task, which would run after

  // the pagehide event is dispatched and so after the associated

  // microtask that runs the following assert.

  // https://html.spec.whatwg.org/multipage/webappapis.html#event-loop-for-spec-authors

  assert_equals(promise_state, 'pending', 'Promise state while inactive');

  // If the first document is restored, then that will occur immediately after

  // pagehide (and associated microtasks), before the next global task is run.

  // https://html.spec.whatwg.org/multipage/history.html#traverse-the-history-by-a-delta

  await promise_new_task(t);

  if (proxy.navigator.mediaDevices == devices) {

    // The first document was persisted and restored.

    assert_equals(proxy.location.search, '', 'history search');

    await promise_enumerate;

  } else {

    // The first document was not restored, but gets re-fetched.

    await t.step_wait(() => proxy.location.search == '', 'navigation');

    assert_not_equals(proxy.navigator.mediaDevices, devices, 'new realm')

    await proxy.navigator.mediaDevices.enumerateDevices();

    assert_equals(promise_state, 'pending', 'Promise state after discard');

}, 'enumerateDevices with navigation');

</script>