Edit: For those who prefer visual content, I've recorded this as a video on Youtube which you can find at: https://youtu.be/toKW2YLnGFQ
Ok, so I've had to convert some Django projects to use Pytest as the test runner rather than the built in one that Django uses. This is actually pretty straightforward, and I even recorded a Youtube video showing the process.
That's all fine and good, but one of the complaints I've heard from
Django-ista's (is that a term? Djangoites? Django Devotees?) is that it means
now the good old plain
python manage.py test no longer works (well, I suppose
technically it still works, but doesn't use Pytest).
So challenge accepted, as one can certainly create custom manage.py commands in Django, so lets create a custom management command to run our unit tests with Pytest instead of the default built-in runner.
Python Manage.py pytest
So first challenge is "how do we run pytest from Python?" as typically you run Pytest as a command line tool. As it turns out there's docs on how to do this on Pytest's site.
The trick is to
import pytest and then call
pytest.main() passing in the
same command line arguments you'd give to Pytest in the terminal to that
function. As an example:
Would be the same thing as doing
pytest --lf on the command-line. Easy peasy.
So started a basic custom management command in a file called
put it into my Django project's
import pytest from django.core.management.base import BaseCommand class Command(BaseCommand): help = "Runs tests with Pytest" def handle(self, *args, **options): pytest.main()
This works, in that now I can do
python manage.py pytest and it'll run Pytest
as if I just ran the
pytest executable in the current directory.
Cool, but how do I start passing arguments? Typically in a custom Django
management command you define a
add_arguments function and use the
module to define the expected arguments for your custom command. In this case
though, I essentially want the interface to Pytest, which would be non-trivial
to recreate by hand (there's a lot of options on that Pytest executable).
But, with argparse, there is a way to essentially say "accept any arguments",
and that's the
argparse.REMAINDER value for the
argparse.REMAINDER. All the remaining command-line arguments are gathered into a list. This is commonly useful for command line utilities that dispatch to other command line utilities
Perfect, that's exactly what I want. Adding to our management command is straighforward:
import argparse import pytest from django.core.management.base import BaseCommand class Command(BaseCommand): help = "Runs tests with Pytest" def add_arguments(self, parser): parser.add_argument("args", nargs=argparse.REMAINDER) def handle(self, *args, **options): pytest.main(list(args))
Now whatever arguments we pass to our
manage.py pytest command will be passed
directly through to the
pytest.main function. Exactly what I want, and super
But That's Still Different
At this point it worked, but I could still hear those nagging voices saying,
manage.py pytest is not the same as
manage.py test". Fine, as it
turns out though you can override any of the built-in manage.py commands.
The trick is to just create a custom management command with the name of the
command you want to override, and make sure your app is the last one in Django's
INSTALLED_APPS setting. So in our case we could just rename our
management/pytest.py file to
management/test.py and it'd work. But I kinda
liked having both (ie both
manage.py pytest and
manage.py test being
effectively an alias to it). So I created a
management/test.py file and put
in the following:
# Override the built in Django manage.py test with pytest from djangotest.management.commands.pytest import Command
Yup, that's it, 1 line of code. Now doing a
python manage.py test runs Pytest
as the test runner.
Did this all on a test project, source is up on Github at: https://github.com/pzelnip/djangotest
Or if you just want to see the management commands, they're at: https://github.com/pzelnip/djangotest/tree/master/djangotest/management/commands