How would I test, using the same testing code, a C, C++, Perl, and LISP implementation of the same design? I want to use the same testing code so I can demonstrate that I code the same functionality in different languages.
You might want to consider producing a scriptable interface to your code base and testing via that. Implement the scriptable API in each language and Bob's your Father's brother.
You might want take a gander at Developing a timeclock application. It's in Ruby, but I think the point comes across.