How to discover unit tests from your project

Within code snippet below implemented very primitive way to collect your unit tests within your project.  This is not for real project - I know at least two of fancy discovering tools - it's nose and discover , which do same thing in more convenient and accurate way.

I was curious and I did it.

# -*- coding: utf-8 -*-
import os
import sys
import unittest


FILE_ABSPATH = lambda p: os.path.dirname(os.path.abspath(p))
COMPARE_DIRS = lambda a, b: FILE_ABSPATH(a) == FILE_ABSPATH(b)


def collect_tests():
    """
    Function to collect tests from whole project
    """

    basedir = os.path.abspath(os.path.dirname(__file__))
    main_module = os.path.basename(basedir)

    test_file = "tests.py"
    test_dir = "tests"
    tests = []
    new_locals = {}

    for root, dirs, files in os.walk(basedir):
        if test_file in files and \
            os.path.join(root, test_file) != os.path.abspath(__file__):
            tests.append(os.path.join(root, test_file))

        if os.path.dirname(root) == test_dir:
            tests.append(root)

    for test in tests:
        test_path = test.replace(basedir, '').replace('.py', '')
        module_name = "%s%s" % (main_module, test_path.replace('/', '.'))
        __import__(module_name)

        module = sys.modules[module_name]

        for cls in dir(module):
            attr = getattr(module, cls)
            try:
                attr.__module__
            except AttributeError:
                continue

            # we don't want to import anything from current file
            if COMPARE_DIRS(sys.modules[attr.__module__].__file__, __file__):
                continue

            try:
                if issubclass(attr, unittest.TestCase):
                    new_locals[cls] = attr
            except TypeError:
                pass

    return new_locals

# execute tests
if __name__ == '__main__':
    locals().update(collect_tests())
    unittest.main()