Érico Andrei: Plone + pytest: Tips and tricks

Link to talk information on Plone conference website.

Plone loves tests. The first was committed in October 2002 by Sidnei da Silva. We have used lots of different testing framework. I like using pytest. The unittest framework was inspired by Java testing and you see it. pytest is simple and pythonic. It does dependency injection, which can look magical, okay. There is a large ecosystem of plugins. It has support for unittest. There is a Brazilian maintainer.

I have created pytest-plone, built upon zope.pytest. It provides fixtures and helpers. it is the default in cookieplone templates. Take a look at plone.distribution and plone.exportimport for examples.

Golden rules

If you need a Plone site in your test, you need to wrap your test in a class. That helps for not tearing down everything after every test. Start with a method that gets portal and probably get_fti, and use @pytest.fixture(autouse=True).

Use @parametrize to run the same test function with multiple inputs and output.

Use fixtures.

Trust and love pytest plugins. There are plugins for running the tests in random order, or in parallel. Code coverage is a plugin. You can start a docker container.

Use helpers in pytest-plone to check that your latest upgrade step matches the metadata profile version. Check that your add-on is installed.

plone-pytest 1.0 is coming. Small problem: the tests are breaking on Python 3.9.

Write more tests with less code.  I will sprint on pytest-plone.