'Asssign a calculator to a counter_type. Raise when the calculator is missing.'

def test_calculator_decorator(self):

    @calculator(123456)
    def do_something(*args, **kwargs):
        'A    function    that    does    something.'
        pass
    self.assertEquals('do_something', do_something.__name__)
    self.assertEquals('A    function    that    does    something.', do_something.__doc__)
    self.assertTrue(get_calculator(123456))
    self.assertRaises(UndefinedCalculator, get_calculator, 654321)
