  
      def get_renderer_mock(self, media_type):
          return type('RendererMock', (BaseRenderer,), {
              'media_type': media_type,
          })
  
      def test_determine_accept_list_accept_header(self):
          """
          Test that determine_accept_list takes the Accept header.
          """
 
</s> remove         request = RequestFactory().get(url, HTTP_ACCEPT=','.join(accept_list))
 </s> add         kwargs = {}
        if accept_list is not None:
            kwargs['HTTP_ACCEPT'] = HTTP_ACCEPT=','.join(accept_list)
        request = RequestFactory().get(url, **kwargs) </s> remove         self.assertTrue(isinstance(renderer, JRenderer))
 </s> add         self.assertTrue(renderer, jrenderer)

    def test_determine_renderer_default(self):
        """
        Test determine renderer when Accept was not specified.
        """
        prenderer = self.get_renderer_mock('application/pickle')

        response = self.get_response(accept_list=None, renderers=(prenderer,))
        renderer, media_type = response._determine_renderer()
        self.assertEqual(media_type, '*/*')
        self.assertTrue(renderer, prenderer) </s> remove         raise ErrorResponse(content={'detail': 'Could not satisfy the client\'s Accept header',
 </s> add         raise ImmediateResponse(content={'detail': 'Could not satisfy the client\'s Accept header', </s> remove         PRenderer = self.get_renderer_mock('application/pickle')
        JRenderer = self.get_renderer_mock('application/json')
 </s> add         prenderer = self.get_renderer_mock('application/pickle')
        jrenderer = self.get_renderer_mock('application/json')
        })()
  
      def get_renderer_mock(self, media_type):
          return type('RendererMock', (BaseRenderer,), {
              'media_type': media_type,
        })()
  
      def test_determine_accept_list_accept_header(self):
          """
          Test that determine_accept_list takes the Accept header.
          """
keep keep keep keep replace keep keep keep keep keep
 cleaned a bit Response/ResponseMixin code, added some documentation + renamed ErrorResponse to ImmediateResponse 
djangorestframework/tests/response.py