Add tests for addDemoMonitors

Server/controllers/monitorController.js

@@ -469,7 +469,7 @@ const addDemoMonitors = async (req, res, next) => {
 
     return res.status(200).json({
       success: true,
-      message: successMessages.MONITOR_DEMO_ADDED,
+      msg: successMessages.MONITOR_DEMO_ADDED,
       data: demoMonitors.length,
     });
   } catch (error) {