Create a unit tests
===================

1. create the file test_MODULE_NAME. It must have a main fn. Each testcase
   should be an int function, 1 for error 0 if not. 

2. create the make target. In the Makefile add test_MODULE_MANE: ...
   To find which modules add to the target try building and then for each "undefined reference to"
   grep:
   grep -rn ^FN_NAME
   If ^FN_NAME gives not results find the function and insert a newline so that the fn name is
   at the begninnig of the line like:
   Err
   the_function(void) ...

