Enable testing functions

[Rindrics]

Feature Request

Is your feature request related to a problem? Please describe.

I need tests before adding features to this tool

Describe the solution you'd like

• add testing tool as dev dependency
• enable it to run on CI

Describe alternatives you've considered

Are you willing to resolve this issue by submitting a Pull Request?

• Yes, I have the time, and I know how to start.
• Yes, I have the time, but I don't know how to start. I would need guidance.
• No, I don't have the time, although I believe I could do it if I had the time...
• No, I don't have the time and I wouldn't even know how to start.

[nilbuild]

Thank you for the suggestion. Feel free to take it up.