IDLE *will* fail if idleConf.SetOption is called with a wrong config-type (KeyError) or the wrong number of other arguments (TypeError).  I did not add the check because it does not cover the non-default callbacks (the majority), let alone all the other idleConf calls.  The important thing is to make sure that every callback gets called in a test (and indeed, eventually, that every line is executed).  Enhancing the doc string should be enough.