var gcm = require('node-gcm');
  var sender = new gcm.Sender('');
  var message = new gcm.Message({
           collapseKey: 'demo',
           priority: 10,
           contentAvailable: true,
           delayWhileIdle: true,
           timeToLive: 3,
           restrictedPackageName: "",
           data: {
              title: 'Test 5',
              body: 'Test 5 for notification, marwan if you see this let me know the number of test on slack',
            },
            notification: {
              title: "test",
              body: "This is a notification that will be displayed if your app is in the background."
           }
        });


        var regTokens = [];
        sender.send(message, { registrationTokens: regTokens }, function (err, response) {
           if (err) console.error('error : ',err);
           else console.log('response',response);
        });