Import path for unit tests

[Ben Finney]

Howdy all,

My practice when writing unit tests for a project is to make 'test/'
subdirectories for each directory containing modules I want to test.

    project-foo/
    +-- lib/
    |   +-- test/
    +-- data/
    +-- gui/
    |   +-- test/
    +-- server/
        +-- test/

This means that I need to use relative paths to import the subject
code into the unit test module.

    import unittest

    import sys
    sys.path.append('..')
    import foomodule

    class Test_Foo(unittest.TestCase):
        # ...

This works, so long as the foomodule is *not* in the path before the
appended '..' directory. When writing unit tests for a development
version of a package that is already installed at an older version in
the Python path, this fails: the unit tests are not importing the
development version of foomodule.

What is the common idiom here? I can conceive of several possible ways
to get around it, all of which seem hackish to some degree.

-- 
 \            "It's not what you pay a man, but what he costs you that |
  `\                                          counts."  -- Will Rogers |
_o__)                                                                  |
Ben Finney