Yeah it might be good to have a generic testunit/shoulda/testspec/rspec controller -> test/spec -> controller toggle.
Currently you have the "Go to xxx" commands which are Shift+Cmd+Alt+Down from nearly any Rails file to any other related Rails file.
RSpec bundle has Shift+Ctrl+Down.
Perhaps we could have a version of that for Controller -> Test/Spec -> Controller.
For developing Bundle commands, 99% of the code isn't in the Command text field. Rather, all the code is in Support/lib + /bin and tests in Support/test.
Have a look in there and see what you can make of it. Ping any questions to the mailing list.
Cheers
Nic