Relative imports with unittest in Python

I am trying to use Python unittest and relative imports, and I can't seem to figure it out. I know there are a lot of related questions, but none of them have helped so far. Sorry if this is repetitive, but I would really appreciate any help. I was trying to use the syntax from PEP 328 http://www.python.org/dev/peps/pep-0328/ but I must have something wrong.

My directory structure is:

project/
    __init__.py
    main_program.py
    lib/
        __init__.py
        lib_a
        lib_b
    tests/
        __init__.py
        test_a
        test_b

I run my tests using:

python -m unittest test_module1 test_module2

test_a needs to import both lib/lib_a and main_program. This is the code from test_a I am trying to use for the import:

from ..lib import lib_a as lib
from ...project import main_program

both raise this error:

ValueError: Attempted relative import in non-package

All of my init.py files are currently empty.

Any specific advice would be greatly appreciated!!

Edit:

This may be the answer: Python Packages? I'm still verifying if this will work.

Edit II:

To clarify, at this point I have attempted to run my test file in 3 different ways:

project/tests $ python -m unittest test_a
project/tests $ python -m test_a
project/tests $ ./test_a

All three fail with the same error as above. When I use the same three syntaxes but in the project directory, I get this error:

ValueError: Attempted relative import beyond toplevel package

Thanks again.

In my experience it is easiest if your project root is not a package, like so:

project/
  test.py
  run.py
  package/
    __init__.py
    main_program.py
    lib/
      __init__.py
      lib_a
      lib_b
    tests/
      __init__.py
      test_a
      test_b

However, as of python 3.2 , the unittest module provides the -t option, which lets you set the top level directory, so you could do (from package/):

python -m unittest discover -t ..

More details at the unittest docs.