Add unit tests for core

**Feature request**
It would be great to have backup for store.

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

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

Start by locating the core configuration handling and existing unit-test layout; the issue does not name specific files or entry points. Clarify what store backup should cover and how it is triggered, then verify the default-disabled configuration and the agreed backup behavior with focused tests.

Written by the indexing model from the issue text.