MQTT Broker and Client testing

[Domoticatorino]

Dear all,
I am testing MQTT apps. I have a MQTT client which send a Json topic to LM Broker.

After that I set LM MQTT client app in order to read data sent received by. Topic name I use is the same I set on the MQTT client.

LM client app is correctly link to broker but how can I understand if data are received from broker? 

I follow the script but there's a way, before setting the scripts, if data are correctly reveived by broker? 

Thanks.

BR