Answer from stackoverflow
It's a lot easier if you can upgrade to standard/pro and install ReSharper - it's got a really nice integrated test runner. However, if you can't do that...
* Launch the NUnit GUI
* Load the relevant tests, from debug builds
* In Visual Studio, attach to the NUnit GUI process
* Set your breakpoints
* Launch the relevant testIt's a bit of a pain, but when you've got the shortcut keys memorised (Alt-P is attach to process, IIRC - but check) it's not too bad
http://stackoverflow.com/questions/274619/what-is-the-best-way-to-debug-...