Using pytest with a src layer

问题

pytest recommends including an additional directory to separate the source code within a project:

my_package
├── src  # <-- no __init__.py on this layer
│   └── my_package
│       ├── __init__.py
│       └── util_module
│           ├── __init__.py
│           └── utils.py
└── tests
    ├── __init__.py
    └── test_util_module
        ├── __init__.py
        └── test_utils.py

Sadly, they say nothing¹ about how imports in the test code should work in such a case, which work for my IDE just fine in this naive example², but causes the following error with pytest:

my_package $ pytest

====================== test session starts ======================
platform linux -- Python 3.6.4, pytest-3.5.1, py-1.5.3, pluggy-0.6.0
rootdir: /home/user/workspace/my_package, inifile:
collected 0 items / 1 errors     

============================ ERRORS =============================
___ ERROR collecting tests/test_util_module/test_utils.py ___
ImportError while importing test module '/home/user/workspace/my_package/tests/test_util_module/test_utils.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
tests/test_util_module/test_utils.py:1: in <module>
    from test.test_module.some_file import starify
E   ModuleNotFoundError: No module named 'my_package.util_module'
!!!! Interrupted: 1 errors during collection !!!!!

I can fix the issue by changing the import of the test to from src.my_package.util_module.utils import starify, but then my IDE complaints about the src part being redundant, so I'd like to keep it out.

1: Not the case any more. As of version 3.7.3, pytest recommends the editable install also featured in @hoefling's answer at the top of its good practices.

2: Setup is virtualenv env -p python3.6; source env/bin/activate; pip install pytest

回答1:

Adjusting the PYTHONPATH (as suggested in the comments) is one possibility to solve the import issue. Another is adding an empty conftest.py file in the src directory:

$ touch src/conftest.py

and pytest will add src to sys.path. This is a simple way to trick pytest into adding codebase to sys.path.

However, the src layout is usually selected when you intend to build a distribution, e.g. providing a setup.py with (in this case) explicitly specifying the root package dir:

from setuptools import find_packages, setup


setup(
    ...
    package_dir={'': 'src'},
    packages=find_packages(where='src'),
    ...
)

and installing the package in the development mode (via python setup.py develop or pip install --editable .) while you're still developing it. This way, your package my_package is correctly integrated in the Python's site packages structure and there's no need to fiddle with PYTHONPATH.

来源：https://stackoverflow.com/questions/50155464/using-pytest-with-a-src-layer

标签

python

pytest