Accessing argparse arguments from the class
You could do this by making the test classes take args as parameter, and crafting a custom make_suite method instead of unittest.makeSuite, like this:

class ParentTest(unittest.TestCase):
    def __init__(self, methodName='runTest', args=None):
        super().__init__(methodName)
        self.args = args

class Test1(ParentTest):
    def test_if_verbose(self):
        print("Success!") if self.args.verbose else ""

class Test2(ParentTest):
    pass

if __name__ == '__main__':
    parser = argparse.ArgumentParser(add_help=False)
    parser.add_argument("-?", "--help",     action="help",                        help="show this help message and exit" )
    parser.add_argument("-v", "--verbose",  action="store_true", dest="verbose",  help="increase output verbosity" )
    parser.add_argument('files', nargs='*')
    args = parser.parse_args()

    print(args.verbose)

    def make_suite(testcase_class):
        testloader = unittest.TestLoader()
        testnames = testloader.getTestCaseNames(testcase_class)
        suite = unittest.TestSuite()
        for name in testnames:
            suite.addTest(testcase_class(name, args=args))
        return suite

    # Add tests.
    alltests = unittest.TestSuite()
    alltests.addTest(make_suite(Test1))
    alltests.addTest(make_suite(Test2))

    result = unittest.TextTestRunner(verbosity=2).run(alltests) # Run tests.
    sys.exit(not result.wasSuccessful())


The sample output is the same as the original code:


$ python t2.py ; python t2.py -v
False
test_if_verbose (__main__.Test1) ... ok

----------------------------------------------------------------------
Ran 1 test in 0.000s

OK
True
test_if_verbose (__main__.Test1) ... Success!
ok

----------------------------------------------------------------------
Ran 1 test in 0.000s

OK



The code in my answer was inspired by these posts:


https://stackoverflow.com/a/17260551/641955
http://eli.thegreenplace.net/2011/08/02/python-unit-testing-parametrized-test-cases/