test_harness.h allows for easy mocking in C unit tests. It is a very low tech approach to unit test boilerplating automation for the C language.
K - eep
I - t
S - imple and
S - eparated.
Please refer to the presentation at https://github.com/t-lo/test_harness/blob/master/test_harness_h_KISS_testing_for_C.pdf?raw=true for a quick introduction.