I would like to setup unit tests for a python application. There are many ways to do this, including doctest and unittest, as well as 3rd-party frameworks that leverage python’s unittest, such as pytest and nose.

I found the plain-old unittest framework to be the easiest to work with, although I often run into questions about how best to organize tests for various sized projects. Regardless of the size of the projects, I want to be able to easily run all of the tests, as well as run specific tests for a module.

The standard naming convention is “test_ModuleName.py”, which would include all tests for the named module. This file can be located in the same directory (package) as the module, although I prefer to keep the tests in their own subdirectory (which can easily be excluded from production deployments).

In other words, I end up with the following:

package/
 - __init__.py
 - Module1.py
 - Module2.py
 - test/
    - all_tests.py
    - test_Module1.py
    - test_Module2.py

Each of the test_*.py files looks something like this:

#!/usr/bin/env python
# vim: set tabstop=4 shiftwidth=4 autoindent smartindent:
import os, sys, unittest

## parent directory
sys.path.insert(0, os.path.join( os.path.dirname(__file__), '..' ))
import ModuleName

class test_ModuleName(unittest.TestCase):

    def setUp(self):
        ''' setup testing artifacts (per-test) '''
        self.moduledb = ModuleName.DB()

    def tearDown(self):
        ''' clear testing artifacts (per-test) '''
        pass

    def test_whatever(self):
        self.assertEqual( len(self.moduledb.foo()), 16 )


if __name__ == '__main__':
    unittest.main()

With this approach, the tests can be run by all_tests.py, or I can run the individual test_ModuleName.py.

The all_tests.py script also must add the parent directory on the path, i.e.,

#!/usr/bin/env python
# vim: set tabstop=4 shiftwidth=4 autoindent smartindent:
import sys, os
import unittest

## set the path to include parent directory
sys.path.insert(0, os.path.join( os.path.dirname(__file__), '..' ))

## run all tests
loader = unittest.TestLoader()
testSuite = loader.discover(".")
text_runner = unittest.TextTestRunner().run(testSuite)