test to show to_predicate doesn't need to take a symbol

Author: jezhiggins

unit/analyses/variable-sensitivity/constant_abstract_value/to_predicate.cpp

@@ -49,5 +49,17 @@ SCENARIO(
       auto obj = make_constant(val2, environment, ns);
       THEN_PREDICATE(obj, "x == 2");
     }
+    WHEN("(1 + 2) = 3")
+    {
+      auto val1 = from_integer(1, type);
+      auto c3 = make_constant(from_integer(3, type), environment, ns);
+
+      auto pred = c3->to_predicate(plus_exprt(val1, val2));
+      THEN("predicate is (1 + 2) = 3")
+      {
+        auto repr = expr_to_str(pred);
+        REQUIRE(repr == "1 + 2 == 3");
+      }
+    }
   }
 }