Add unit tests and improve code coverage

[rosenbalchev]

Hi 👋
First of all, thanks for this great project—I really enjoy using it at home.
I noticed that the repository currently does not include unit tests and has 0% code coverage. I’d like to contribute by improving this area.
As part of my learning process, I’m also exploring AI-assisted development tools like GitHub Copilot, Codex, and Claude. I thought this project would be a great opportunity to experiment with adding tests without modifying the core logic.
My goal is to:

Introduce unit tests
Increase code coverage
Keep the existing implementation unchanged

I’ll be using this as a learning playground, but I’ll make sure any contributions are clean and useful for the project.
Let me know if you have any preferences regarding:

Testing frameworks
Coverage targets
Contribution guidelines specific to testing

Thanks again for the awesome project!
Rosen

[rosenbalchev]

Added initial implementation and added code coverage >50% in the initial commint:
#61