Switch Django Evolution's test suite to use pytest.

Review Request #11917 — Created Jan. 9, 2022 and submitted — Latest diff uploaded


Django Evolution


Historically, we've used nose as the test runner, with a custom test
runner script responsible for setting up a Django environment for the
given version of Django.

Unfortunately, nose 1.x hasn't been updated in a long while, and isn't
compatible with modern versions of Python 3. The forks also don't
support Python 3 very well. nose2 does, but is so different that it's
not a great option for us.

Instead, we're moving to pytest. This is a much more modern test
runner with a lot of interesting capabilities and a wide ecosystem of

We now use this and define all our custom setup logic using pytest
hooks in conftest.py. This handles Django setup, and adds a --db
option for specifying which test database we want to use to run the

Developers can now run pytest directly to run the test suite. The old
./tests/runtests.py still works, but is deprecated, and merely wraps
pytests anyway.

Tested with manual test runs, using a variety of parameters.

Ran the whole Python/Django compatibility matrix using tox. All
tests passed.