datalog: magic over rule with negation regression test (227/227)

lib/datalog/tests/magic.sx

@@ -197,6 +197,20 @@
         6)
 
       ;; dl-magic-query: end-to-end driver, doesn't mutate caller's db.
+      ;; Magic over a rule with negated body literal — propagation
+      ;; rules generated only for positive lits; negated lits pass
+      ;; through unchanged.
+      (dl-mt-test! "magic over rule with negation"
+        (let
+          ((db (dl-program
+                 "u(a). u(b). u(c). banned(b).
+                  active(X) :- u(X), not(banned(X)).")))
+          (let
+            ((semi (dl-query db (list (quote active) (quote X))))
+              (magic (dl-magic-query db (list (quote active) (quote X)))))
+            (= (len semi) (len magic))))
+        true)
+
       ;; Magic over a rule whose body contains an aggregate.
       ;; The rewriter passes aggregate body lits through unchanged
       ;; (no propagation generated for them), so semi-naive's count