anchor.diff:  
   (define-test delete-unknown-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)
         (assert-error 'ernestine-database:unknown-album-error
   		    (ernestine-database:delete-album backend artist-name album-name)))))
   
   (define-test add-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))))
  +    (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
  
positive.code: 
  (define-test cant-add-existing-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:   `(let ((,backend (ernestine-database:get-backend :prevalence "/tmp/foo/")))
       ,@body))
  
  (defun generate-random-name (token)
    (format nil "~A-~A" token (gensym)))
  
  (define-test add-artist
    (with-prevalence-backend (backend)
      (let* ((name (generate-random-name "artist"))
  	   (data (ernestine-database:make-artist backend name nil)))
        (assert-true (eq (type-of data) 'ernestine-database:artist)))))
  
  (define-test delete-artist
    (with-prevalence-backend (backend)
      (let* ((name (generate-random-name "artist")))
        (ernestine-database:make-artist backend name nil)
        (assert-true (ernestine-database:delete-artist backend name)))))
  
  (define-test cant-add-existing-artist
    (with-prevalence-backend (backend)
      (let* ((name (generate-random-name "artist")))
        (ernestine-database:make-artist backend name nil)
        (assert-error 'ernestine-database:existing-artist-error
  		    (ernestine-database:make-artist backend name nil)))))
  
  (define-test delete-unknown-artist
    (with-prevalence-backend (backend)
      (let* ((name (generate-random-name "artist")))
        (assert-error 'ernestine-database:unknown-artist-error
  		    (ernestine-database:delete-artist backend name)))))
  
  (define-test add-album
    (with-prevalence-backend (backend)
      (let* ((artist-name (generate-random-name "artist"))
  	   (album-name (generate-random-name "album")))
        (ernestine-database:make-artist backend artist-name nil)
        (let ((data (ernestine-database:make-album backend
  						 artist-name
  