begin migrating tests to pure prolog, correct bug in toplevel

src/tests/predicates.pl

@@ -0,0 +1,37 @@
+
+:- dynamic(p/2).
+:- dynamic(p/3).
+
+:- dynamic(q/1).
+
+p(_, a).
+p(b, _).
+
+test_queries_on_predicates :-
+    findall(Y, p(x, Y), [a]),
+    findall(X, p(X, a), [_,b]),
+    findall(X, p(b, X), [a,_]),
+    findall(X, p(X, X), [a,b]),
+    p(b, a),
+    \+ p(a, b),
+    retract(p(_,a)),
+    retract(p(b,_)),
+    assertz(p(_, _,a)),
+    assertz(p(_,a,_)),
+    assertz(p(_,_,a)),
+    findall(X, p(c,d,X), [a,a]),
+    findall(X, p(a,a,a), [a,a,a]),
+    \+ p(b,c,d),
+    findall(., retract(p(_,_,_)), _),
+    assertz(p(_, a)),
+    assertz(q(z)),
+    findall(Y, p(_,Y), [a]),
+    p(x,a),
+    p(_,a),
+    \+ p(_,b),
+    assertz((p(X, Y) :- q(Z), p(X, X))),
+    once(p(X,b)),
+    retract((p(X, Y) :- q(Z), p(X, X))),
+    retract(q(z)).    
+
+:- initialization(test_queries_on_predicates).