Hi Wolfgang,
a re-organisation has already taken place when ThisG did the restructuring.
There are now a number of different Projects for the Tests - check out trunk in a separate directory if you haven't done so after ThiasG's changes and load Solution 'OpenPetra.sln', which is found in directory \trunk\delivery\projects\sharpdevelop3.
This re-organisation is only about Projects, and does not contain different Solutions for different Test targets. I am not sure we would need that, though - what might be handy would be an auto-generated 'Testing.sln' that would only contain the Projects of the Test targets.