Add unit tests for middleware

**Feature request**
It would be great to have serialization for auth.

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

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

The issue names no files, tests, or entry points, and its title asks for middleware tests while the body requests auth serialization. First clarify which work is intended and locate the middleware and configuration entry points; done should include the requested behavior and focused unit-test coverage.

Written by the indexing model from the issue text.