With this tutorial, you have learned how to create a basic MQTT test. You can now improve it in multiple ways:
Fill in the message by getting data from your database or file. See the Data-Driven Tutorial for additional information on creating data-driven functional tests.
Validate the received message by using assertions to make sure that your service responds quickly enough and sends the correct response.
Simulate multiple simultaneous connections to your server. For that, you can run your test cases as separate load testing scenarios. Learn more about running load tests in the Load Testing Getting Started Tutorial.