Python unittest import issues

Question

This is my project set up:

my_project
    ./my_project
         ./__init__.py
         ./foo
              ./__init__.py
              ./bar.py
         ./tests
             ./__init__.py
             ./test_bar.py

Inside test_bar.py I have the following import statement: from foo import bar

However when I run python /my_project/tests/test_bar.py I get this error:

ImportError: No module named foo.

Any ideas on how to fix this?

Answer 1

Think about what is on your PYTHONPATH. The toplevel package for your project is my_project, so that must be the start of any import for something in your project.

from my_project.foo import bar

You could also use a relative import, although this isn't as clear, and would break if you ever changed the relative location of the module you were performing this import from.

from ..foo import bar

---

Ideally, the test folder is not a package at all, and is not part of your application package. See pytests's page on good practices. This requires that you add a setup.py to your package and install it to your virtualenv in develop mode.

pip install -e .

---

Don't run the tests by pointing directly at a file within your application. After structuring/installing your project correctly, use the discovery mechanism for whatever framework you're using to run the tests for you. For example, with pytest, just point at the test folder:

pytest tests

Or for the built-in unittest module:

python -m unittest discover -s tests

Answer 2

import sys
sys.path.append('/path/to/my_project/')

Now you can import

from foo import bar