I have been making use of NUnit more and more as I reep the benifits. Recently I started using NCover, a code coverage tool. It provides stats on the code that is executed - and more importantly the code that isn't. With NCover explorer/browser you get a very good overall view of those stats, see a screenshot:
  http://www.kiwidude.com/blog/uploaded_images/NCoverExplorer-742691.png

Hook this up with your unit tests and you get a pretty good idea about how good you unit tests are...

Hmmm. After witing lots more unit tests (!) for my code I really started to appreciate NCover. Possibly the biggest area that lacked testing was the "exception" handling parts, i.e. performing "expected exception" tests with NUnit and making sure that if my code recieved an invalid parameter that an exception was handled correctly etc.

Verdict: NCover and NCoverExplorer Rocks.

Links:

• http://ncover.org/
• http://www.nunit.org/
• http://www.kiwidude.com/blog/2006/01/ncoverexplorer-debut.html

One of my recent ideas is around creating my own test runner (like NUnit) but is geared towards single line tests using attributes on the methods. I think I might be a little too ambitious here though! It would be a quick way of churning out lots of simple unit tests that would increase code coverage (especially now that I can see the gaps so easily!)