PlaybackManager implements Playback.Callback { @Override public void setCurrentTrack(Track track) { Timber.d("setCurrentTrack %s", track); queueManager.setCurrentTrack(track); } PlaybackManager(QueueManager queueManager, PlaybackServiceCallback serviceCallback,
                  AndroidClock androidClock, Playback playback); Playback getPlayback(); @Override void onCompletion(); @Override void onPlaybackStatusChanged(); @Override void setCurrentTrack(Track track);  }
@Test public void setCurrentTrack() { Track currentTrack = createTrack(); playbackManager.setCurrentTrack(currentTrack); verify(mockQueueManager, times(1)).setCurrentTrack(currentTrack); }