If you use external programs as part of your testing process, the only reliable way I have found to get their test results merged is to run each of them individually, like:
PERL5OPT=-MDevel::Cover; export PERL5OPT; for program in
(where I use "test.pl" for the main test program, and the other *.pl are the external programs).
Have I missed something really simple, or is this the easiest way to get complete test coverage results? It takes a lot longer to run each program twice -- once by "test.pl", and once by itself. Comments are encouraged.