Assignment02RulesSpec: add test case

java-feedback-rascal/test/Assignment02RulesSpec.rsc

 module Assignment02RulesSpec
 
 import Set;
+import IO;
 
 import SpecUtil;
 import Assignment02Rules;
@@ -9,4 +10,10 @@ test bool allGood()
 {
   errors = allAssignment02Rules(loadTestProject("assignment02-hangman-example-solution"));
   return isEmpty(errors);
+}
+
+test bool wrongProject()
+{
+  errors = allAssignment02Rules(loadTestProject("assignment01-good"));
+  return "There should be one class called Gallows" in { message | error(message, _) <- errors };
 }
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