How would you even test a UI library? For example, if some weird input makes the bar charts too spread apart, how do you convert that to a unit test? If you tried to unit test this, you'd either be fully reproducing the actual source code for spacing logic or you'd be hard-coding in thresholds that might all break if the maintainer decides on a UI change such as "increase the spacing for bar charts having many grouped bars".
It seems for UI projects, testing can only cover about 1-10% of the issues that eventually end up on the GitHub issue tracker, so 25% of your time on this project would go toward writing tests, which would save you 1-10% of your time. Doesn't make sense.
You can test more than you'd realize: The generated math, the number of axes and number of visible points, etc. I'm not saying its def. a valuable use of time here, but I've been surprised how investing a little bit in helper methods (like, `getSelectedOption` or `isVisible`, etc) can generate quite useful and expressive unit tests.
