Add unit tests for types

**Feature request**
It would be great to have filtering for middleware.

**Use case**
Many users need this functionality for production deployments.

**Implementation idea**
Add a new config option `enable_filtering` with default `false`.

The issue names no files, tests, or entry points, and its title conflicts with the feature request. Start by locating the middleware configuration and existing type tests, then determine where enable_filtering belongs and how its default false value should be verified. Done means middleware filtering works for the stated production use case and the behavior is covered by unit tests.

Written by the indexing model from the issue text.