You could use the exported job in your jUnit tests. A job can be called as command from from OS or you use the libraries and call from the entry class runInTos(String contextArgs) One problem remains, in the Open Source release there is currently no way to build the job outside the studio.
Ok I might be able to call the job from outside, but how I compare the result with some expected result. I cannot compare the file generated (I generate PDF) but usually (in other development tool) I make Junit tests to call this unit and compare the output (before pdf generation) of this unit using different use cases according the expected result. I do not want something fancy, only to be able to test parts of my jobs (of course continuous integration would be the ultimate goal)