Reorganized the unit test abstraction once more, now I'm really happy with it. Thanks for all the useful suggestions everyone. I will not spam the list with my patches anymore, it is here, with screenshots, explanation and .zip:
http://www.katjaas.nl/pdunittests/pdunittests.html
Please have a look at it, try it out. There's a few examples which should clarify the idea. In my experience, it takes on average a couple of minutes to create a test patch this way. I hope it is now decent enough to become part of a standardized method for testing Pd-extended.
Katja