Visual Studio understands a number of configurations of your program. In particular, it understands a production configuration and a debug one. You can set up your debug configuration to start up a new copy of NUnit. So if you set a breakpoint and then start with debugging, NUnit will run. You can select the test of interest in the NUnit GUI, then run, andvoila!you get the breakpoint you were interested in.
To set up your startup program, check the Help in Visual Studio for Modifying Project Properties And Configuration Settings. Dont expect it to be entirely accurate, however. Its not in my version, though it is close. Heres how to do it in my Visual Studio, Microsoft Development Environment 2002, Version 7.0.9466.
Select the project in the Solution Explorer. Bring up the project Properties, via a right-click on the project name or via the Project menu. Click Configuration Properties, Debugging. Youll get a window like this:
Set the window as shown. Under Debug Mode, select Program. Then, under Start Application, use the little ... button to browse to the NUnit- GUI.exe file and select it. Apply or OK the window. From now on, when you do Debug/Start, or press F5, NUnit will start up. Works fine.