Add unit tests for routes

**Feature request**
It would be great to have caching for lib.

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

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

First resolve the mismatch between the title, which requests unit tests for routes, and the body, which requests caching for lib. Identify the relevant route tests and configuration entry point, then define completion as an `enable_caching` option whose default is `false`, with coverage for the requested behavior.

Written by the indexing model from the issue text.