We can't use relative imports any more since the tests are now located outside the package. I had to add __init__.py to Tests/feaLib/ so that pytest does not get confused by the presence of two test files with the same basename: i.e. Tests/feaLib/builder_test.py and Tests/feaLib/builder_test.py https://github.com/pytest-dev/pytest/issues/774 http://stackoverflow.com/questions/12582503/py-test-test-discovery-failure-when-tests-in-different-directories-are-called