Subversion rocks :-)

Actually, it just occurred that subversion would offer another solution to the separation of tests issue. You could create a separate directory in a subversion repository that had a per-module Makefile.PL and external definition links to the appropriate module and test code from the main directory.

You could then checkout a module that could be worked on stand alone, and have all changes automatically checked into the main tree.

No idea if/how you would do this in CVS.