gistfile1.txt

$ python2 test-unittest.py Foo.test_b
b
.
----------------------------------------------------------------------
Ran 1 test in 0.000s

OK

test-unittest.py

import unittest

class Foo(unittest.TestCase):
    def test_a(self):
        print 'a'

    def test_b(self):
        print 'b'

unittest.main()