      def get_response(self, request):
          # This is the simplest place we can hook into to patch the
          # request object.
          force_authenticate(request, self._force_user, self._force_token)
          return super(ForceAuthClientHandler, self).get_response(request)
  
  
  class APIClient(APIRequestFactory, DjangoClient):
      def __init__(self, enforce_csrf_checks=False, **defaults):
          super(APIClient, self).__init__(**defaults)
 
</s> remove         super(ForceAuthClientHandler, self).__init__(*args, **kwargs)
 </s> add         super().__init__(*args, **kwargs) </s> remove         super(APIClient, self).__init__(**defaults)
 </s> add         super().__init__(**defaults) </s> remove         class AuthRaisesAttributeError(object):
 </s> add         class AuthRaisesAttributeError: </s> remove         request = super(ViewSetMixin, self).initialize_request(request, *args, **kwargs)
 </s> add         request = super().initialize_request(request, *args, **kwargs) </s> remove         instance = super(Field, cls).__new__(cls)
 </s> add         instance = super().__new__(cls)
        return super().get_response(request)
      def get_response(self, request):
          # This is the simplest place we can hook into to patch the
          # request object.
          force_authenticate(request, self._force_user, self._force_token)
        return super().get_response(request)
  
  
  class APIClient(APIRequestFactory, DjangoClient):
      def __init__(self, enforce_csrf_checks=False, **defaults):
          super(APIClient, self).__init__(**defaults)
keep keep keep keep replace keep keep keep keep keep
 Dropped Python 2 compatibility. (#6615)

Thanks to Jon Dufresne (@jdufresne) for review.

Co-authored-by: Asif Saif Uddin <auvipy@gmail.com>
Co-authored-by: Rizwan Mansuri <Rizwan@webbyfox.com> 
rest_framework/test.py