ITEC 380 - Testing Prolog Programs

It is useful to have a way to test prolog programs, and here is one way to do it. Create a group of predicates that test your your prolog program, and put the predicates in a file. Here is an example file, called p1Test.P:

 
o :- 
p2, p3, p4,
q2, q3, q4,
r2, r3, r4,
s2, s3, s4.

p2 :- checkLast([b, a], a).
p3 :- checkLast([a], a).
p4 :- not checkLast([], a).

q2 :- checkNextToLast([b, a], b).
q3 :- not checkNextToLast([a], a).
q4 :- not checkNextToLast([], a).

r2 :- checkLastTwoReversed([b, a], [a,b]).
r3 :- not checkLastTwoReversed([a], [a,b]).
r4 :- not checkLastTwoReversed([], [a,b]).

s2 :- checkReverseLastTwo([b, a], [a,b]).
s3 :- not checkReverseLastTwo([a], [a,b]).
s4 :- not checkReverseLastTwo([], [a,b]).


:- consult(p1).

checkLast(X, Y) :- write(X), write(Y), last(X, Y).
checkNextToLast(X, Y) :- write(X), write(Y), nextToLast(X, Y).
checkLastTwoReversed(X, Y) :- write(X), write(Y), lastTwoReversed(X, Y).
checkReverseLastTwo(X, Y) :- write(X), write(Y), reverseLastTwo(X, Y).

• Note that the check functions write the arguments and then call the predicate.
• Some should fail, and they are called with not.
• Predicate o calls all of the tests.
• consult(p1). causes the file p1.P to be loaded.

  /software/unix/bin/xsb  <  loadP1Test   

[p1Test].
o.
p2.
p3.
p4.
q2.
q3.
q4.
r2.
r3.
r4.
s2.
s3.
s4.

If all of the tests work, then this will be seen by the success of o and you do not need to look at the results of the other tests. If o fails, then you can look at the other tests to see which one failed.