Interop Testing Plan

The test material is based upon the current OASIS consultation draft of the specification.

The test material described below can be found in the Paho testing git repository.

Conformance Statements

The specification contains a list of identified conformance statements, which are labelled with sequence numbers. Although the statements are to a certain extent arbitrary, due to the use of language in the specification (wherever the words MUST or SHOULD are used), nevertheless they are a good place to start in determining conformance. I anticipate adding more statements to this list in due course, but for now we will go with the list as identified in the current version of the specification.

I have extracted the list into a spreadsheet where tests for both MQTT clients and servers are briefly described. I am using this as a coverage checklist to view progress of the current test material.

Model Based Testing

I have taken the approach of what can be described as model based testing. A fully automated test at its core is comprised of two sets of data:

• input sequences
• expected results, or outputs.

MQTT is a client/server protocol, meaning that in general there are two components, clients and servers to test.

Test Material Components

I'll start by describing the components of the test material.

Test Broker

A test or "model" broker is in the package mqtt/broker. The first question I will be asked (thanks Ian Skerrett) is why write another broker, when Mosquitto, RSMB or others already exist. The reasons are:

• I already had one written before (but that is not really important)
• a model broker need not have all the implementation details of a production server
• the model is seeded with conformance statements - it knows when they have been executed
• the model is written in Python and is intended to be simple and serve as an illustration and clarification for the specification.

I hope the source can be scrutinized and discussed by the community, both for understanding the specification, and discussion of MQTT server implementation. The source consists of the following files:

• start.py
• MQTTBrokers.py