[Zope-dev] Porting zope.dottedname to Python 3

[Marius Gedminas]

This ought to be a wiki page somewhere, but since I can't even figure out how
to log in to http://wiki.zope.org, I'll settle for an email.

I'm trying to dip my toes into Python 3 migration of zope.*.  Stephan
Richter suggested I start with zope.dottedname, since it's a very
trivial package with no dependencies.

The mailing list archive contains a lot of advice.  (If this were a wiki
page, I'd add links to the relevant emails).  What I'm trying to do
here is to provide a concrete example of the porting pattern discovered
by others (especially Lennart Regebro and Tres Seaver):

- make sure you've got Python interpreters for all the interesting
  versions (2.6, 2.7, 3.2, 3.3) (duh)

- check out the sources (duh)

    svn co svn+ssh://svn.zope.org/repos/main/zope.dottedname/trunk

- get the tests to pass with 'python setup.py test'

    this basically means you need a
    test_suite='zope.dottedname.tests.test_suite', which was already
    there, and a tests_require=[...] if your tests have any
    dependencies.

- get the tests to pass using tox -e py27, i.e. add a tox.ini

    existing packages on github.com/zopefoundation provided examples
    there; here's the one I started with for zope.dottedname:

        [tox]
        envlist =
            py26,py27,py32,py33
            # you can also add pypy because why not?

        [testenv]
        commands =
            python setup.py test -q

- add a MANIFEST.in, because tox builds sdists and installs them into
  virtualenvs under ./.tox, and because setuptools doesn't understand
  Subversion 1.7 working trees

    I used 'check-manifest --create' from https://gist.github.com/4277075

- see how the tests fail with tox -e py32 and/or py33

- decide that the easiest way to fix them for zope.dottedname would be
  to add a renormalizer

    https://github.com/zopefoundation/zope.dottedname/commit/1a2440c#diff-3

    Alternative (and perhaps better) strategies would include rewriting
    doctests into unittests

- this adds a test dependency on zope.testing:

   + edit setup.py and add tests_require=['zope.testing'],
   + also add extras={'testing': ['zope.testing']} because
   + you need to update buildout.cfg to require zope.dottedname[zope.testing]
   + also edit tox.ini and add

       [testenv]
       deps = zope.testing

    (otherwise setup.py test will unpack zope.testing et al into $PWD and
    clutter your working tree)

- get the tests passing (detox is very useful here as it runs tests for
  all Pythons in parallel)

- check test coverage

    I tried to get tox -e coverage working, gave up, and used the old

      python setup.py bootstrap
      bin/buildout
      bin/test --coverage=coverage

    method

- update Trove classifiers in setup.py:

      'Programming Language :: Python :: 2.6',
      'Programming Language :: Python :: 2.7',
      'Programming Language :: Python :: 3.2',
      'Programming Language :: Python :: 3.3',

- update CHANGES.txt and indicate Python 3.x support

- bump version number in CHANGES.txt and setup.py to 4.0.0 to indicate
  Python 3.x support

- maybe migrate to github while you're at it

- make a release to PyPI eventually (zest.releaser FTW)


Marius Gedminas
-- 
http://pov.lt/ -- Zope 3/BlueBream consulting and development
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