Example on how to structure a package and testing modules

README.md

Arrange files like this:

apple/
  __init__.py
  apple.py
tests/
  test_everything.py

And execute with:

export PYTHONPATH=.
py.test

(This Gist was used to answer a question at stackoverflow)

apple.py

def eat():
    return 'eaten'

test_everything.py

from apple import apple

def test_apple():
    assert apple.eat() == 'eaten'

Wanted to notice that you can run set an environment variable just for one command:

PYTHONPATH=. pytest

# or in fish shell
env PYTHONPATH=. pytest

It worked for me. Thanks for your example on SO!