Add support for serialized rollback

[luzfcb]

Fixes #329.

TODO:

• add test(s)

This is the code made by @blueyed in #353 with some additional inspired by #619

This issue reported by @aaugustin seems to be a blocker
https://code.djangoproject.com/ticket/26552

[luzfcb]

Is there any particular reason for the current Travis-ci configuration only testing against MySQL using Python2.7 + Django 1.11, and not testing against the new versions of django and python3?

[blueyed]

Is there any particular reason for the current Travis-ci configuration only testing against MySQL using Python2.7 + Django 1.11, and not testing against the new versions of django and python3?

It is meant to have a smaller build matrix.

[lapp0]

Your branch gives me this warning:

  /nix/store/ih3aih50m19mdhlr07f1lhandghj07qv-python3.7-pytest-django-3.5.1/lib/python3.7/site-packages/pytest_django/fixtures.py:223: PytestDeprecationWarning: The `funcargnames` attribute was an alias for `fixturenames`, since pytest 2.3 - use the newer attribute instead.
    if "django_db_serialized_rollback" in request.funcargnames:

This is a very important PR for me, thanks for implementing it!

[luzfcb]

@lapp0 Thanks for pointing me the warnings. I already fix the code.

Anyway, a key duplication error is occurring, however, this seems to be erratic behavior since the same commit causes the test suite to fail differently on two different instances of travis-ci

https://travis-ci.org/pytest-dev/pytest-django/builds/605222978

https://travis-ci.org/luzfcb/pytest-django/builds/605222952

[luzfcb]

The ticket https://code.djangoproject.com/ticket/26552 was fixed in Django master branch.

django/django#12736
django/django#12651
django/django#12453

[aleehedl]

@luzfcb Apart from resolving conflicts and adding tests, is there something else that needs to be done before this is ready for merging?

Has someone come up with some kind of a temporary workaround for this problem before this PR is finalized?

[coiax]

@aleehedl There are a number of work arounds in the comments of #329, although I haven't used any of them.

[daniel-ruiz]

@luzfcb Hi! I found this PR after encountering an error in a large Django test suite and it would be fantastic to count on this feature to solve that problem!
Can I help in moving this forward? I'm not knowledgeable of pytest's internals, so I'd appreciate some pointers in order to get started 😄

[bluetech]

A PR which will replace this PR is in #970. I intend to merge and release it in a few days. Comments and tests are welcome.