Our testing used the IWL MQTT Test Suite (IMTS) to test:

the Rabbit MQ MQTT broker with MQTT 3.1.1.
the Active MQ Artemis MQTT broker with MQTT 3.1.1.
the Eclipse Mosquitto (TM) broker with MQTT 3.1.1 and MQTT 5.

These brokers are used in communications exchanges for Internet of Things (IoT) applications and devices.

The IWL MQTT Test Suite generates a battery of MQTT messages and test traffic against each broker to determine how it handles the traffic. The tests include:

Basic Operation
Compliance with the MQTT v.3.1.1 and/or the MQTT v5 specification, as appropriate.
Robustness (in the face of pathological input conditions)

Why is this important?

IoT devices are used in many mission-critical environments that depend on their robustness and resilience to attacks, changing network conditions, and a variety of other factors. A poorly implemented MQTT device will fail in unpredictable ways that may be difficult to diagnose and correct. Thus, the importance of well- tested, reliable MQTT implementations.