Hi Lukas, I noticed that you override two times the changes I pushed in the PPCompositeTest, and as expected, these changes break most of the external tests :). In particular, there are two things that I found useful: - the result instance variable holding the side effect of executing #parse:rule:. This is useful for reusing the grammar tests in the parser tests. - the fail:rule: method for negative tests. In the last comment, you mentioned that this was due to incompatibilities with Helvetia. Should we create a new class with these utilities? Cheers, Doru -- www.tudorgirba.com "When people care, great things can happen."