I am currently looking for some good options to do this as well. As a result, I came across this question, and a few other potential candidate solutions. Admittedly, I haven’t tried any of them yet, so I can’t speak to their quality, but at least they are some other avenues potentially worthy of researching.
- Jenni Tennison’s Unit Testing Package
- UTF-X Unit Testing Framework
- Juxy
- XTC
Additionally, I found the following article to be informative in terms of a general methodology for unit testing XSLT.
Unit test XSL transformations