Speaker: Casey Kinsey
You should care about the speed of unit tests because if you're serious about testing you should be serious about having lots of tests and running those tests frequently. Slow test suites get in the way of testing goals because your developers won't run the tests, especially for perceived small changes.
Write unit tests. The Django test client is an integration test. Don't use the test client if you are trying to write a unit test. So establish a good ratio of unit tests to integration tests. For every method that contains business logic there should be a unit test. For each page/view/user path there should be an integration test.
Set up tests cautiously. Only include stuff you really need for every test in this case. Don't put stuff in setUp just to be lazy. Take advantage of setUpClass and tearDownClass instead, which run once per test case instead of once per test in the test case.
Work whenever possible with read-only non persisted data. Use in-memory model instances.
# instead of this
car = Car.objects.create(make='Scion', model='tC')
# do this
car = Car(make='Scion', model='tC')
# and don't save the car
Avoid fixtures, because they are loaded/purged between each test case. They don't adapt with your data-model and schema changes will result in test failures.
When you do write, use in-memory sqlite. (just don't provide a name for the db in your test settings and it will be in-memory)
Try to live without django.test.TestCase.
Use mock to emulate model instances. Set the attributes you need for testing directly. Use the "spec" argument to give guidelines. Then you'll have no model/ORM overhead. "spec" is a reference to the real class.
Don't be afraid to invest engineering efor into your test suite. Write tools to help you test. Leverage 3rd party tools. Use decorators, custom test runners, if you need to.
And if you can't test the code efficiently, refactor the code. If the code is difficult to write tests for, your code probably needs to be refactored anyway.
Developer consultant who works for Celerity.
@cordiskinsey