2. Running and writing tests

Good code needs tests.

A project like django CMS simply can’t afford to incorporate new code that doesn’t come with its own tests.

Tests provide some necessary minimum confidence: they can show the code will behave as it expected, and help identify what’s going wrong if something breaks it.

Not insisting on good tests when code is committed is like letting a gang of teenagers without a driving licence borrow your car on a Friday night, even if you think they are very nice teenagers and they really promise to be careful.

We certainly do want your contributions and fixes, but we need your tests with them too. Otherwise, we’d be compromising our codebase.

So, you are going to have to include tests if you want to contribute. However, writing tests is not particularly difficult, and there are plenty of examples to crib from in the code to help you.

2.1. Running tests

There’s more than one way to do this, but here’s one to help you get started:

# create a virtual environment
virtualenv test-django-cms
# activate it
cd test-django-cms/
source bin/activate
# get django CMS from GitHub
git clone git@github.com:divio/django-cms.git
# install the dependencies for testing
# note that requirements files for other Django versions are also provided
pip install -r django-cms/test_requirements/django-1.4.txt
# run the test suite
django-cms/runtests.py

It can take a few minutes to run.

When you run tests against your own new code, don’t forget that it’s useful to repeat them for different versions of Python and Django.

2.2. Writing tests

Contributing tests is widely regarded as a very prestigious contribution (you’re making everybody’s future work much easier by doing so). Good karma for you. Cookie points. Maybe even a beer if we meet in person :)

2.2.1. What we need

We have a wide and comprehensive library of unit-tests and integration tests with good coverage.

Generally tests should be:

  • Unitary (as much as possible). i.e. should test as much as possible only one function/method/class. That’s the very definition of unit tests. Integration tests are interesting too obviously, but require more time to maintain since they have a higher probability of breaking.
  • Short running. No hard numbers here, but if your one test doubles the time it takes for everybody to run them, it’s probably an indication that you’re doing it wrong.
  • Easy to understand. If your test code isn’t obvious, please add comments on what it’s doing.