          class MockView(View):
              permissions = ()
  
              def get(self, request):
                  return self.response_class({'a':1, 'b':2, 'c':3})
  
          self.req = RequestFactory()
 
</s> remove                 return Response({'a':1, 'b':2, 'c':3})
 </s> add                 return self.response_class({'a':1, 'b':2, 'c':3}) </s> remove     renderers = (DocumentingHTMLRenderer, JSONRenderer)
 </s> add     renderer_classes = (DocumentingHTMLRenderer, JSONRenderer) </s> remove     renderers = (DocumentingHTMLRenderer, )
 </s> add     renderer_classes = (DocumentingHTMLRenderer, ) </s> remove     renderers = (RendererA, RendererB)
 </s> add     renderer_classes = (RendererA, RendererB) </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)
            response_class = Response
          class MockView(View):
              permissions = ()
            response_class = Response
  
              def get(self, request):
                  return self.response_class({'a':1, 'b':2, 'c':3})
  
          self.req = RequestFactory()
keep add keep keep keep keep keep
 cleaned a bit Response/ResponseMixin code, added some documentation + renamed ErrorResponse to ImmediateResponse 
djangorestframework/tests/accept.py