It depends what "working as exepcted" means.
If you are looking only for return values you can do like this:
create a script which calls al your functions and saves the associated return values in a text file.
run that script from virtuoso , using load()... save the output.txt file in something like golden_image.txt.
Keep a copy of of your CDS.log file .
Letter when you have modified the functions, you just have to run
virtuoso -replay CDS.log
then you have to compare output.txt with golden_image.txt
If output means something more complex (e.g. create/modify cells, etc, etc) then you must do a diff like of the golden_output and the output of the last run.
anyway to automate the jobs you may want to use "virtuoso -replay", eventually "virtuoso -nograph -reply ..." to not splash the windows al over the screen .