public void testUniqueArtist() {
Artist artist1 = new Artist("john");
Album album1 = new Album("coolAlbum");
album1.artist=artist1;
album1.replaceDuplicateArtist();
album1.save();
// name must be unique
Artist artist2 = new Artist("john");
Album album2 = new Album("coolAlbum2");
album2.artist=artist2;
album2.replaceDuplicateArtist();