def setUp(self):
        """
        Create a L{UserDatabase} with no user data in it.
        """
        self.database = UserDatabase()
        self._counter = SYSTEM_UID_MAX + 1

        Create a L{UserDatabase} with no user data in it.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/python/test/test_fakepwd.py