Yes, test_font_set could be split up.  But then the setup would have to be repeated for each, and it would be harder to verify that each .set() call was being tested the same way.  

The event graph for indent_scale is a simple linear chain, and the simple liner test mirrors that.

The combined test of bold_toggle and set_samples is not what I wanted, but I prefer it to the alternative of depending on an undocumented internal detail of the tcl wrapper maker (_tkinter, I suspect).