Nice to see you using JSFUnit in a different way. I've often wondered how far you can get with this type of testing if you use JSFUnit to start the session and then just do lots of fine-grained unit tests in-container.
You might also take a look at the Arquillian which seems to have this kind of testing as its main goal. So you would use Arquillian for fine-grained in-container tests and then use JSFUnit for course-grained tests where you need to test integrated application logic and UI.
That being said, I'm not sure why you are getting that error. I'm going to see if someone from the Seam team has any ideas.
Thank you for your promt answer. And thanks for introducing Arquilian. I'll keep an eye on this project. But since it hasn't already reached alpha stage, I'll be loyal to JSFUnit
In the meantime I've deactivated the problematic testcases. So it would be very nice if you could inform me if there are any news on this topic. Of course, I will check the seam-forum at regular intervals.