Error handling for providing no valid tests in Jenkins master-trigger

Change-Id: I6fa8ff402bba55b6d548d0a1024142f5e77d0b6e
diff --git a/TestON/JenkinsFile/MasterTrigger.groovy b/TestON/JenkinsFile/MasterTrigger.groovy
index 776d50d..82b5802 100644
--- a/TestON/JenkinsFile/MasterTrigger.groovy
+++ b/TestON/JenkinsFile/MasterTrigger.groovy
@@ -56,6 +56,10 @@
     timeout( time: INITIALIZATION_TIMEOUT_MINUTES, unit: "MINUTES" ){
         init()
     }
+    if ( selectedTests == [:] && manually_run ){
+        echo "No valid tests provided. Check if the provided test(s) is/are in test.json, and try again.\n\nProvided Tests:\n" + testsParam
+        throw new Exception( "No valid tests provided. Check if the provided test(s) is/are in test.json, and try again." )
+    }
     timeout( time: pipelineTimeOut, unit: "MINUTES" ){
         runTests()
         generateGraphs()