Header only.
Designed to be easily adaptable to other test suites.
Test cases are either free void functions or classes with a test() method.
The TestCollector script simply greps for simple patterns of each, and creates a .c file that builds a testsuite. That testsuite can use any test framework you like, such as CppUnit. I.e. my stuff can be considered just a simple interface to CppUnit, although it also works with other test frameworks.
URL? Project page? Development status?