a nifty bash script testing technique via logging

In the following git hub link to the testing code a simple technique to check whether something has been set or went via a particular execution path is demonstrated. In this particular use case the actual code to test should implement a logic as follows: - check that a var is set , if not set to default value ( the var is the "mysql_scripts_dir" As the time of writing the function is not even ready ... the challenge was how-to test that the var was set according to the desired logic ... echoing the var into the /tmp/ or /var/log / dir is out of question - since ( at least for this tool ) the tool should write data only bellow its root dir ... The solution ?! Echo the value of the var into the implementation code's tool log file ( the line contains the pid of the run ), build the desired log line result into the testing code and verify it by the child pid - after the code has executed there should be 1 and only 1 occurrence of that log line ... I might be doing something reeeaally wrong here ... if you do have better ideas please comment ...