unit testing

[Perry Smith]

I took something called "yari" and added "buttons" to it and now I have 
"yari-with-buttons".  What it does is it parses the output of a command called 
"ri" (from Ruby's documentation system).  The problem is that the output of ri 
changes (like the wind)... and the internal API changes even faster.

What I need to do is come up with some unit tests so that I can see if it 
parses all the different types of buffers that ri can produce correctly.  Is 
there any quasi-formal test unit system already available?

Thank you,
pedz