I didn't port zope.testrunner to Python 3, but I did make its tests pass (eventually) on 3.2 and 3.3. - If python setup.py test passes, and tox -e py27 passes, and detox indicates that all Python versions also pass all tests --- that might just mean you have a bug in your setup.py that doesn't do sys.exit(1) in case of failures. Oops. - Python guarantees that random.random() will return the same sequence of floats if you initialize the RNG with the same seed. This guarantee doesn't extend to methods like random.shuffle()! Workaround: random.shuffle(a_list, random.random) Note: I'm talking about numeric seeds here. If you use strings as seeds, you'll also have to deal with the different hashing methods: Python 2.x uses hash(your_string), which is already non-portable between 32-bit and 64-bit platforms, while Python 3.2+ uses SHA-512, unless you do random.seed(your_seed, version=1). Anyway, don't use strings as seeds (because 32-/64-bit nonportability of string hashes). Marius Gedminas -- http://pov.lt/ -- Zope 3/BlueBream consulting and development