Testing was done manually, using a streamlit program.

Is there any testing we can do here? To check if the rendering as expected?

I have a proposal for regression testing in the playwright branch. It makes use of Playwrights visual snapshots to compare the current version against stored images under version control.

However, when working on the #1877 issue, I got an idea that may be even simpler. We can use _to_png() with fixed size to make visual snapshots.

I have a boatload of regression tests that I'd like to check in. I think it would make folium development much more solid if we had better snapshot testing.