[TEST] thrown error when there are no REST tests to run

src/test/java/org/elasticsearch/test/rest/junit/RestTestSuiteRunner.java

@@ -336,6 +336,10 @@ public class RestTestSuiteRunner extends ParentRunner<RestTestCandidate> {
             }
         }
 
+        if (rootDescription.getChildren().size() == 0) {
+            throw new InitializationError("No tests to run");
+        }
+
         if (!parseExceptions.isEmpty()) {
             throw new InitializationError(parseExceptions);
         }