tor-browser

The Tor Browser
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context-time-monotonic-on-setsinkid.https.html (3655B)

      1 <!DOCTYPE html>
      2 <html>
      3 <head>
      4 <title>currentTime and getOutputTimestamp().contextTime after setSinkId</title>
      5 <meta name="flags" content="--use-fake-device-for-media-stream">
      6 <script src="/resources/testharness.js"></script>
      7 <script src="/resources/testharnessreport.js"></script>
      8 </head>
      9 <body>
     10 <script>
     11 promise_test(async t => {
     12  // A timeout for waiting for the audio context to transition to a new state.
     13  const TRANSITION_TIMEOUT = 250;
     14 
     15  const context = new AudioContext();
     16  t.add_cleanup(() => context.close());
     17  await context.resume();
     18 
     19  // Let it run for a bit to ensure time values are advancing.
     20  await new Promise(resolve => t.step_timeout(resolve, TRANSITION_TIMEOUT));
     21 
     22  const initialCurrentTime = context.currentTime;
     23  const initialContextTime = context.getOutputTimestamp().contextTime;
     24  assert_true(
     25      initialCurrentTime > 0,
     26      'Pre-check: currentTime should be > 0 after running for a while');
     27  assert_true(
     28      initialContextTime > 0,
     29      'Pre-check: contextTime should be > 0 after running for a while');
     30 
     31  const devices = await navigator.mediaDevices.enumerateDevices();
     32  const audioOutputDevices = devices.filter(d => d.kind === 'audiooutput');
     33  if (audioOutputDevices.length < 2) {
     34    // This test requires at least two audio output devices.
     35    assert_unreached(
     36        'Not enough audio output devices to run this test. Need at least 2.');
     37  }
     38 
     39  // Find a device that is not the current one.
     40  const newDeviceId =
     41      audioOutputDevices.find(d => d.deviceId !== context.sinkId)?.deviceId;
     42  if (!newDeviceId) {
     43    assert_unreached('Could not find a different device to switch to.');
     44  }
     45 
     46  // Capture timestamps just before the switch.
     47  const timeBeforeSetSinkId = context.currentTime;
     48  const contextTimeBeforeSetSinkId = context.getOutputTimestamp().contextTime;
     49 
     50  await context.setSinkId(newDeviceId);
     51 
     52  // Capture timestamps immediately after the switch.
     53  const timeAfterSetSinkId = context.currentTime;
     54  const contextTimeAfterSetSinkId = context.getOutputTimestamp().contextTime;
     55 
     56  // The time should not go backwards for either currentTime or contextTime.
     57  assert_true(
     58      timeAfterSetSinkId >= timeBeforeSetSinkId,
     59      `currentTime should not go backwards after setSinkId. Before: ${
     60          timeBeforeSetSinkId}, after: ${timeAfterSetSinkId}`);
     61  assert_true(
     62      contextTimeAfterSetSinkId >= contextTimeBeforeSetSinkId,
     63      `contextTime should not go backwards after setSinkId. Before: ${
     64          contextTimeBeforeSetSinkId}, after: ${contextTimeAfterSetSinkId}`);
     65 
     66  // The time should not jump too far ahead. A small delta is expected for the
     67  // device change while the context is running.
     68  assert_true(
     69      timeAfterSetSinkId - timeBeforeSetSinkId < 1,
     70      `setSinkId took too long or currentTime jumped. Before: ${
     71          timeBeforeSetSinkId}, after: ${timeAfterSetSinkId}`);
     72 
     73  // Let it run for a bit more to ensure it's still advancing.
     74  await new Promise(resolve => t.step_timeout(resolve, TRANSITION_TIMEOUT));
     75 
     76  const finalCurrentTime = context.currentTime;
     77  const finalContextTime = context.getOutputTimestamp().contextTime;
     78  assert_true(
     79      finalCurrentTime > timeAfterSetSinkId,
     80      `currentTime should increase after setSinkId. After switch: ${
     81          timeAfterSetSinkId}, final: ${finalCurrentTime}`);
     82  assert_true(
     83      finalContextTime > contextTimeAfterSetSinkId,
     84      `contextTime should increase after setSinkId. After switch: ${
     85          contextTimeAfterSetSinkId}, final: ${finalContextTime}`);
     86 }, 'currentTime and getOutputTimestamp().contextTime should not reset after ' +
     87       'setSinkId');
     88 </script>
     89 </body>
     90 </html>