Sadly, usually tests are written after the fact to satisfy a code coverage requirement. Perhaps that's why people hate testing. That's why I did!

At my startup we're indirectly tackling difficulties associated with unit testing. Our tool Alive [0] is an interactive programming extension to Visual Studio that made me really enjoy writing tests first and then implementing the features - when with each keystroke I get to see what the code does.

[0] http://comealive.io/