Py.test won't find tests

Question

I'm using pytest , but in this project, the tests are in the regular modules, not modules labeled test_stuff.py

I tried to change the test discovery by adding a pytest.ini file in the root of my project with the following contents:

[pytest]
python_files = *.py
python_functions=test_*

When I run the tests, still nothing is found:

$ py.test
================================ test session starts ================================
platform linux2 -- Python 2.7.6 -- py-1.4.20 -- pytest-2.5.2
collected 0 items 

=================================  in 0.03 seconds ==================================

My layout could hardly be simpler:

$ ls
foo.py
pytest.ini

Where foo.py contains:

def add(a, b):
    return a+b

def test_add():
    assert 4 == add(2, 2)

Answer 1

Upgrade!

$ sudo pip install pytest --upgrade

This setup works with pytest 2.8, fails with 2.5.