Using Prolog to Generate Test Data

#!/usr/bin/swipl -q -t run -f

subset([], []).
subset([E | Tail], [E | NTail]) :-
   subset(Tail, NTail).
subset([_ | Tail], NTail) :-
   subset(Tail, NTail).

validate(0, 1).
validate(X, Max) :-
   Max > 1,
   Y is Max - 1,
   (
      X = Y
   ;
      validate(X, Y)
   ).

generate(L) :-
   validate(N, 5),
   length(L, N).

main :-
   generate(L),
   subset(['A', 'A#', 'B', 'C', 'C#', 'D',
           'D#', 'E', 'F', 'F#', 'G', 'G#'], L),
   format("~q~n", [L]),
   fail.

main :-
   true.

run :-
   main, halt.