Add unit tests for types

**Feature request**
It would be great to have import for controllers.

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

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

The issue names no files, tests, or entry points and its title conflicts with the request about importing controllers. First clarify whether the goal is unit tests for types or an `enable_import` configuration option, then locate the configuration and controller-loading paths. Done should include a stated behavior and corresponding tests.

Written by the indexing model from the issue text.