Check is an open source unit testing framework in the style of xUnit for C programs. The framework is considered stable—even though it has not reached its 1.0 release yet—and is available in the package distribution systems of most Linux distributions, as well as for Windows and OS X. Check is used by some well-known projects such as GStreamer. ==Example of Check unit test== Test writing using Check is very simple. The file in which the checks are defined must include check.h as so: