* All of these should return 0 if ok or a value != 0 on errors.
*
* Then, at the end of your module_test you can write:
+ * \code
* #include TEST_ONLY(whatuneed.h)
* #include TEST_ONLY(whatuneed.c)
* #include TEST_ONLY(...)
*
* TEST_MAIN(module);
+ * \endcode
*
* The macro TEST_ONLY expand to nothing in non-TEST mode or to
* the specified filename if _TEST is defined.