Testing code that uses an RTOS API

Colin Walls, Mentor Graphics
Embedded.com (April 16, 2015)

Embedded application software, which is designed to work under the control of a real time operating system, presents an interesting debugging and testing challenge. The code is most likely littered with RTOS system API (Application Program Interface) calls, which need to be verified, along with the logic applied to any response received. Ideally, the testing process would involve linking the application to the RTOS and debugging. However, this introduces a number of other unknowns and necessitates a target execution environment (which may or may not be the final hardware). It would be useful if this testing could simply be done on a host computer, as PCs are readily available. This article explores an approach to making progress in testing such code by running it natively and using a "test harness".

The concepts discussed here arose after a talk about OS-aware debuggers at a conference and someone asked whether there is a good technique for unit testing of code for a multi-threaded application. They were considering an environment where a number of engineers were working on an embedded application (using Nucleus RTOS). Each guy was developing one or more tasks, which interact with one another and those written by other engineers. The questioner was wondering how these engineers could make some solid progress with testing and debugging ahead of building the complete system.

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