Add unit tests for middleware

**Description**
Currently hooks lacks proper serialization support.

**Proposed solution**
Add configurable serialization with sensible defaults.

**Priority**: Low/Medium

Start by locating the hooks and middleware implementation and any existing unit-test files. Determine how serialization currently works and what configurable defaults the project expects; done means middleware hooks serialize correctly across the supported cases and the behavior is covered by unit tests.

Written by the indexing model from the issue text.