Issues #2 and #6 propose some significant changes to the codebase. It will be helpful to develop a test suite afterward to ensure the existing functionality remains the same for future changes. Unit tests should be fairly straightforward, but functional tests will take some time. Developing a test suite also provides a great ROI when it comes to working on this project on and off.

I'm going to use doctest as the testing framework to learn something new. It seems to be pretty popular for how new it is so I'm hoping that it becomes a standard alongside Catch2 in some time. In the event that it doesn't, they're both pretty similar so I'll be making a lateral.

doctest is a header-only library and it seems pretty flexible so I have a few options for adding it to my project:

1. manually download and include the header
2. add the repository as a submodule
3. install using vcpkg

I plan to install using vcpkg since the project already has support for that. Should I find the need to add more dependencies to this project, it'll be nice in the future to have them consolidated.