((GroupArtist) group).addArtist(memberA);
((GroupArtist) group).addArtist(memberB);
Track trackMockA = EasyMock.createMock(Track.class);
group.addTrack(trackMockA);
assertTrue(group.getTracks().contains(trackMockA));
assertTrue(memberA.getTracks().contains(trackMockA));
assertTrue(memberB.getTracks().contains(trackMockA));