anchor.diff:  
   (define-test delete-album
     (with-prevalence-backend (backend)
  -    (let* ((artist-name (format nil "artist-~A" (gensym)))
  -	   (album-name (format nil "album-~A" (gensym))))
  +    (let* ((artist-name (generate-random-name "artist"))
  +	   (album-name (generate-random-name "album")))
         (ernestine-database:make-artist backend artist-name nil)
         (ernestine-database:make-album backend
   				     artist-name
  
positive.code: 
  (define-test delete-unknown-song
    (with-prevalence-backend (backend)
      (let* ((artist-name (format nil "artist-~A" (gensym)))
  	   (album-name (format nil "album-~A" (gensym)))
  	   (song-name (format nil "song-~A" (gensym))))
        (ernestine-database:make-artist backend artist-name nil)
        (ernestine-database:make-album backend
  				     artist-name
  
negative.code: 
  (define-test delete-song
    (with-prevalence-backend (backend)
      (let* ((artist-name (generate-random-name "artist"))
  	   (album-name (generate-random-name "album"))
  	   (song-name (generate-random-name "song")))
        (ernestine-database:make-artist backend artist-name nil)
        (ernestine-database:make-album backend
  				     artist-name
  