It would be nice to define a button eg "Test". This would eg send all the plugin settings to a defined action (eg Controller or API) and output / show the returned response.
For example a "FileSynchronizer" plugin could have one or multiple test buttons. When pressing "Test" next to "Source directory" it would list all files that would be synchronized. When pressing another "Test" button it would check whether syncing one file actually works.
This is not super trivial and not very high value so moving it to mid term.
:+1: This would be a useful diagnostic for debugging user installs as well.