mozilla-release/testing/web-platform/tests/mediacapture-record/MediaRecorder-disabled-tracks.https.html

<!doctype html>
<html>
<head>
  <title>MediaRecorder Disabled Tracks</title>
  <link rel="help" href="https://w3c.github.io/mediacapture-record/MediaRecorder.html#mediarecorder">
  <script src="/resources/testharness.js"></script>
  <script src="/resources/testharnessreport.js"></script>
</head>
<script>

  // This test verifies that MediaStream with disabled tracks can be correctly
  // recorded. See crbug.com/878255 for more context.

  [ ["video-only",  {video: true,  audio: false}],
    ["audio-only",  {video: false, audio: true}],
    ["audio-video", {video: true,  audio: true}]]
  .forEach( function(args) {
    async_test(function(test) {
      let recorder;
      const recorderOnDataAvailable = test.step_func(function(event) {
        if (recorder.state != "recording")
          return;

        recorder.onstop = recorderOnStopExpected;
        recorder.stop();
      });

      const recorderOnStopExpected = test.step_func_done();
      const recorderOnStopUnexpected = test.unreached_func('Recording stopped.');
      const recorderOnError = test.unreached_func('Recording error.');

      const gotStream = test.step_func(function(stream) {
        for (track of stream.getTracks())
          track.enabled = false;

        recorder = new MediaRecorder(stream);

        assert_equals(recorder.state, "inactive");
        recorder.ondataavailable = recorderOnDataAvailable;
        recorder.onstop = recorderOnStopUnexpected;
        recorder.onerror = recorderOnError;
        recorder.start();

        assert_equals(recorder.state, "recording");
        recorder.requestData();
      });

      const onError = test.unreached_func('Error creating MediaStream.');
      navigator.mediaDevices.getUserMedia(args[1]).then(gotStream, onError);
    }, args[0]);
  });

</script>