The last time I wrote a C project I used "cunit":
It was nice that I could both compile the test-cases as standalone executables, and also build them into my main application. Running "./foo --tests" to run the test-suite post-installation was very nice for getting user-feedback.
There are a few frameworks for test-suites for C, and I looked around a fair bit before picking this one. Whether it suits you is an open question, but if you're not sold on it feel free to browse:
http://en.wikipedia.org/wiki/List_of_unit_testing_frameworks...