### Question:
TrackCounter { public int getPlayCount(int trackNum) { return trackCounts.containsKey(trackNum)?trackCounts.get(trackNum):0; }  void trackPlayed(int trackNum); void countTrack(int trackNum); int getPlayCount(int trackNum);  }### Answer:
@Test public void test() { blankDisc.playTrack(1); blankDisc.playTrack(3); blankDisc.playTrack(3); blankDisc.playTrack(3); blankDisc.playTrack(4); blankDisc.playTrack(4); assertEquals(1, trackCounter.getPlayCount(1)); assertEquals(0, trackCounter.getPlayCount(2)); assertEquals(3, trackCounter.getPlayCount(3)); assertEquals(2, trackCounter.getPlayCount(4)); }