Why cProfile module doesn't work with unittest?

I would to use cProfile module to profile my unit tests. But when I run

python -mcProfile mytest.py

I got 'Ran 0 tests in 0.000s'. Here is the source code of mytest.py

import unittest

class TestBasic(unittest.TestCase):
    def testFoo(self):
        assert True == True

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

I've tested with other more complex unittests as well. Always got 'Ran 0 tests' if I run it with cProfile. Please help.

UPDATE: My OS is MacOS 10.7 with built-in python 2.7. The same code works properly on ubuntu.