Structure: uvicorn app.main:app runs fine from myproject/. But pytest from the same folder: ChatGPT told me to add sys.path.insert0, ... at the top of every tes

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Question

pytest: ModuleNotFoundError: No module named 'app' but the app runs fine

Solved · 268 views · asked last month by ravi_k · edited

Structure:

myproject/
  app/
    main.py
    services/pricing.py
  tests/
    test_pricing.py

uvicorn app.main:app runs fine from myproject/. But pytest from the same folder:

ImportError while importing test module 'tests/test_pricing.py'.
E   ModuleNotFoundError: No module named 'app'

ChatGPT told me to add sys.path.insert(0, ...) at the top of every test file. There has to be a better way?

What I’ve tried

The sys.path hack (works but ugly), adding init.py to tests/ (didn't help), running from inside tests/.

Comment

The sys.path thing is in half of all ChatGPT test files I've seen. Glad there's a real answer here. ines_data last month · edited

3 answers

Marked as helpful by the asker

marco_pylast month · edited

uvicorn works because python -m-style startup puts the current directory on sys.path. The pytest command doesn't. Tell pytest in config:

# pyproject.toml
[tool.pytest.ini_options]
pythonpath = ["."]
testpaths = ["tests"]

Or run it as python -m pytest, which puts the cwd on the path the same way.

Delete the sys.path lines after that.

Comment

pyproject thing worked, removed the hack from 7 files. Thanks! ravi_k last month · edited

Short and correct. olu_backend last month · edited

olu_backendlast month · edited

For a bigger project the "proper" route is to make the app an installable package ([project] table in pyproject, then pip install -e .). Then imports work the same in tests, scripts and production, no path config at all.

For this size pythonpath = ["."] is completely fine though.

Comment

grace_mwlast month · edited

Third option you'll see in older projects: an empty conftest.py in the project root. With the default import mode pytest puts that folder on sys.path. Works, but the pyproject setting says what it does, so I'd use that.

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pytest: ModuleNotFoundError: No module named 'app' but the app runs fine

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pytest: ModuleNotFoundError: No module named 'app' but the app runs fine

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