The very common directory structure for even a simple Python module seems to be to separate the unit tests into their own test directory:

new_project/
    antigravity/
        antigravity.py
    test/
        test_antigravity.py
    setup.py
    etc.

for example see this Python project howto.

My question is simply What's the usual way of actually running the tests? I suspect this is obvious to everyone except me, but you can't just run python test_antigravity.py from the test directory as its import antigravity will fail as the module is not on the path.

I know I could modify PYTHONPATH and other search path related tricks, but I can't believe that's the simplest way - it's fine if you're the developer but not realistic to expect your users to use if they just want to check the tests are passing.

The other alternative is just to copy the test file into the other directory, but it seems a bit dumb and misses the point of having them in a separate directory to start with.

So, if you had just downloaded the source to my new project how would you run the unit tests? I'd prefer an answer that would let me say to my users: "To run the unit tests do X."