Lessons from zope.testrunner

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

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