CuTest lets you write unit tests for your C code. You should use it because: (1) It has the cutest name, (2) It looks and feels like JUnit, (3) It is cross-platform, (4) It ships in a single .c and .h file for ease of deployment.
cfix is a xUnit unit testing framework for C and C++, specialized for Win32 and NT kernel mode. The aim of the framework is to make the development of test suites as easy as possible while fully exploiting the services provided by Windows.
xUnit is a XP style unit testing framework. xUnit uses a protocol between a front-end to display test results and a test driver linked into applications - removing the link time dependencies between the application and the graphics, formatting libraries.