dx:setof3:12">setof/3 followed by a value-check or using the
setoptions. The following are equivalent tests:
test(member) :- findall(X, member(X, [a,b,c]), Xs), Xs == [a,b,c]. test(member, all(X == [a,b,c])) :- member(X, [a,b,c]).
Error-conditions are tested using the option