Add unit test for issue opencog#2886

Author: ngeiswei

tests/query/PresentUTest.cxxtest

@@ -61,6 +61,9 @@ public:
 
 	void test_literal(void);
 	void test_virtual(void);
+	// TODO: re-enable test_monotonicity as soon as
+	// https://github.com/opencog/atomspace/issues/2886 is fixed.
+	void xtest_monotonicity(void);
 };
 
 void PresentUTest::tearDown(void)
@@ -116,5 +119,29 @@ void PresentUTest::test_virtual(void)
 	logger().debug("END TEST: %s", __FUNCTION__);
 }
 
+/**
+ * Test the monotonicity of PresentLink.  This is for issue
+ * https://github.com/opencog/atomspace/issues/2886
+ *
+ */
+void PresentUTest::xtest_monotonicity(void)
+{
+	logger().debug("BEGIN TEST: %s", __FUNCTION__);
+
+	eval->eval("(load-from-path \"tests/query/present-monotonicity.scm\")");
+
+	Handle query = eval->eval_h("query");
+	Handle results = HandleCast(query->execute());
+	Handle P = an(PREDICATE_NODE, "P");
+	Handle Q = an(PREDICATE_NODE, "Q");
+	Handle expected = al(SET_LINK, al(LIST_LINK, P, Q));
+
+	printf("Expecting: %s\n", expected->to_string().c_str());
+	printf("Got: %s\n", results->to_string().c_str());
+	TS_ASSERT_EQUALS(results, expected);
+
+	logger().debug("END TEST: %s", __FUNCTION__);
+}
+
 #undef al
 #undef an

tests/query/present-monotonicity.scm

@@ -0,0 +1,46 @@
+;; Query
+(define query
+  (let* (
+     ;; Constants
+     (R (Predicate "R"))
+     (A (Execution (Schema "A")))
+     ;; Variables
+     (P (Variable "$P"))
+     (Q (Variable "$Q"))
+     ;; Clauses
+     (P→Q (Quote
+            (Implication
+              (Unquote P)
+              (Unquote Q))))
+     (Q∧A (And Q A))
+     (Q∧A→R (Implication
+              Q∧A
+              R)))
+    ;; Query
+    (Get
+      (VariableSet P Q)
+      (Present P→Q Q∧A→R))))
+
+;; KB
+
+;; Culprit
+(Implication
+  (And
+    (Predicate "Qbis") ; Culprit
+    (Execution (Schema "A"))
+  )
+  (Predicate "R"))
+
+;; Premises
+(Implication
+  (Predicate "P")
+  (Predicate "Q"))
+(Implication
+  (And
+    (Predicate "Q")
+    (Execution (Schema "A"))
+  )
+  (Predicate "R"))
+
+;; PM
+(define results (cog-execute! query))