You can use TAbstractTest.Status
procedure to show some debug messages in DUnit GUI during your tests.
But when I run the group of tests, I can see only the status messages from the last executed test. Can I see the complete log somehow, without selecting each single test to run?
The DUnit source code uses a IStatusListener interface and a public method
procedure TAbstractTest.SetStatusListener(Listener: IStatusListener);
which could be overriden to use a new implementation in your test classes. I have not tried it but it could be the cleanest solution.