Limitations of xUnit Fixtures

Following are a few of the limitations of xUnit fixtures:

• xUnit fixtures don’t show up in -setup-show and -setup-plan. This might seem like a small thing, but when you start writing a bunch of fixtures and debugging them, you’ll love these flags.

• There are no session scope xUnit fixtures. The largest scope is module.

• Picking and choosing which fixtures a test needs is more difficult with xUnit fixtures. If a test is in a class that has fixtures defined, the test will use them, even if it doesn’t need to.

• Nesting is at most three levels: module, class, and method.

• The only way to optimize fixture usage is to create modules and classes with common fixture requirements for all the tests in them.

• No parametrization is supported at the fixture level. You can still use parametrized tests, but xUnit fixtures cannot be parametrized.

There are enough limitations of xUnit fixtures that I strongly encourage you to forget you even saw this appendix and stick with normal pytest fixtures.