DejaGnu uses a single header file, dejagnu.h to assist in unit testing. As this file also produces its one test state output, it can be run stand-alone, which is very useful for testing on embedded systems. This header file has a C and C++ API for the test states, with simple totals, and standardized output. Because the output has been standardized, DejaGnu can be made to work with this test case, without writing almost any Tcl. The library module, dejagnu.exp, will look for the output messages, and then merge them into DejaGnu’s.