Using Visual NUnit I can't debug the code and set breakpoints. So I wanted to attach the VS to the NUnit process, because then I can set the breakpoints and watch, what in variables I have.
But after attached to this process I couldn't look at the breakpoints, because I had no symbol loaded, so the brakepoints were disabled with info: "The brakepoint will not currently be hit. No symbols have been loaded for this document".
After some investigation, I found that, the tests and core projects must have the platform target property set to 'Any CPU' and the Attach to process must be set to nunit-agent.exe, not to nunit.exe. Now the symbols should work. If it doesn't, in debug mode we must go to Debug/Windows/Modules window, and there on the list, there should be out assemblies loaded. Pressing the right mouse button on each of our assemblies we have possibility to show, where on the disc the symbols (*.pdb files) are placed.