@Test public void countsTracks() { assertEquals(2, order.countTracks()); }
public abstract long countTracks();
Order { public abstract long countTracks(); }
Order { public abstract long countTracks(); Order(List<Album> albums); }
Order { public abstract long countTracks(); Order(List<Album> albums); abstract long countRunningTime(); abstract long countMusicians(); abstract long countTracks(); }
Order { public abstract long countTracks(); Order(List<Album> albums); abstract long countRunningTime(); abstract long countMusicians(); abstract long countTracks();  }