Cheat: A minimal unit testing framework for the C programming language

by nkurz • 12 years ago

9 2 12 years ago

exDM69• 12 years ago

A while ago I was looking for a minimal unit testing framework for C. I evaluated these two alternatives:

https://github.com/mity/cutest https://github.com/silentbicycle/greatest

They're about 1/5th the size of the Cheat framework. I ended up using "greatest" because it doesn't do any dynamic allocations (intended for embedded) and I found that an interesting feature (I also do embedded stuff every now and then).

The way Cheat works is rather peculiar:

Imagine a source file including a header file. Then imagine the header file including the source file that included it. Now imagine doing that three times in a row within the same header file. ...

I would like to know the reasoning behind this. It sure seems clever but what is the advantage that this provides?

In the end, I wound up writing my own special purpose testing framework because of the nature of the job at hand. I am writing numerical/scientific code and the problem suffers from a very well understood and documented loss of numerical precision (it is about computing the motion of satellites and planets using Kepler's laws - and the numerical inaccuracy happens near escape velocity). My testing is perhaps closer to stress testing than unit testing.

Here's my test framework (it's only about 300 LOC): https://github.com/rikusalminen/libkepler/blob/master/test/n... https://github.com/rikusalminen/libkepler/blob/master/test/n...

Here's a few example test cases: https://github.com/rikusalminen/libkepler/blob/master/test/k...

The method is 1) create a pseudo random initial setting 2) perform a calculation in two different ways and verify that they match 3) analyze the results and verify that laws of physics apply 4) repeat (about 8 million times by default). My tests use about 15 minutes of CPU time currently, which gives me reasonable confidence that everything works as intended.

tordek• 12 years ago

I would like to know the reasoning behind this. It sure seems clever but what is the advantage that this provides?

Since C provides very little metaprogramming capabilities, this was the only way to obtain what I wanted: Most (if not all) other testing libraries/frameworks require some boilerplate to start testing (namely: defining your `main` function, which calls all of your tests). Additionally, every time you write a new test, you must remember to add it to your `main` function.

I decided that those two things were bothersome enough, so I wrote a proof of concept that evolved into a large project with tons of useful features beyond that.

Cheat: A minimal unit testing framework for the C programming language

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