def test_semaphoreInvalidTokens(self):
        """
        If the token count passed to L{DeferredSemaphore} is less than one
        then L{ValueError} is raised.
        """
        self.assertRaises(ValueError, defer.DeferredSemaphore, 0)
        self.assertRaises(ValueError, defer.DeferredSemaphore, -1)

        If the token count passed to L{DeferredSemaphore} is less than one
        then L{ValueError} is raised.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_defer.py