content: import unittest
  
  from websockets.extensions.base import *
  from websockets.frames import Frame, Opcode
  
  
  class ExtensionTests(unittest.TestCase):
      def test_encode(self):
          with self.assertRaises(NotImplementedError):
              Extension().encode(Frame(Opcode.TEXT, b""))
  
      def test_decode(self):
          with self.assertRaises(NotImplementedError):
              Extension().decode(Frame(Opcode.TEXT, b""))
  
  
  class ClientExtensionFactoryTests(unittest.TestCase):
      def test_get_request_params(self):
          with self.assertRaises(NotImplementedError):
              ClientExtensionFactory().get_request_params()
  
      def test_process_response_params(self):
          with self.assertRaises(NotImplementedError):
              ClientExtensionFactory().process_response_params([], [])
  
  
  class ServerExtensionFactoryTests(unittest.TestCase):
      def test_process_request_params(self):
          with self.assertRaises(NotImplementedError):
              ServerExtensionFactory().process_request_params([], [])
  