Hi all,
Please Note that there was a smiley after my suggestion of regression tests ;-)
On a serious note, regression tests and unit tests are good things with proven positive effects on software quality and supportability and could make finding out if a new build works properly easy, but.....
Adding even unit tests to a mature working application almost never repays the effort to create them, so as I would classify Geany as mature and working, I think it is too late to add even unit tests now, it won't repay the effort.
Glad you decided not to or Geany wouldn't have many of its good features since you would still be writing the unit tests.
At work we use many software packages from lots of places and regularly get suggestions to add unit tests, but it is never worth the effort for an existing package, the few who tried have come away sorry but wiser.
When you do the complete re-write at Geany version 2.0 maybe that would be another story ...
As for the GUI testing, unfortunately all the testers I can find require the application to be accessibility enabled, so that the tests can address widgets by name not screen position and read their content for comparison with expected. What this adds to the application effort I don't know, but again I doubt it is worthwhile for an existing application by the time the tests are written as well.
Cheers Lex