setcan be used to specify a different expected result. See section 2 for details. In this section we illustrate typical test-scenarios by testing SWI-Prolog built-in and library predicates.
Deterministic predicates are predicates that must succeed exactly once and, for well behaved predicates, leave no choicepoints. Typically they have zero or more input- and zero or more output arguments. The test goal supplies proper values for the input arguments and verifies the output arguments. Verification can use test-options or be explicit in the body. The tests in the example below are equivalent.
test(add) :- A is 1 + 2, A =:= 3. test(add, [true(A =:= 3)]) :- A is 1 + 2.
The test engine verifies that the test-body does not leave a choicepoint. We illustrate that using the test below:
test(member) :- member(b, [a,b,c]).