Python Testing with pytest

Avoiding Test File Name Collision

The __init__.py file affects pytest in one way and one way only: it allows you to have duplicate test file names.

If you have __init__.py files in every test subdirectory, you can have the same test file name show up in multiple directories. That’s it—the only reason to have a __init__.py file.

Here’s an example:

$ cd /path/to/code/ch8/dup
$ tree tests_with_init
tests_with_init
├── api
│   ├── __init__.py
│   └── test_add.py
├── cli
│   ├── __init__.py
│   └── test_add.py
└── pytest.ini

We might want to test some add functionality both through the API and through the CLI, so having a test_add.py in both seems reasonable.

As long as we also have a __init__.py file in both the api and cli directories, ...