Please consider why this could be extremely useful.
Typically,  for a sufficiently large codebase, we have a humongous testsuite - broken down by 
components.

To add/update testcases in the CVS world is relatively easy - just COPY over the parent directory 
(with the "CVS" directories contained in it) from somewhere that the directory is visible ; make ur 
changes; add and commit. 
It is this behavior that is highly desirable - checking out codebases wont kill you, checking out entire 
test repositories will