A friend at work is always saying how important it is to unit test. His main argument is that unit testing makes refactoring easier. This is something I've heard before but never really thought about. I have refactored lots of code and written lots of unit tests, but I've never really thought deeply about their relationship with each other. Today I decided it was time to consider this issue. So I did some Googleing. I found the following link which is a short blog post where someone discusses the relationship. This solidified my understanding. So, if you want to
start thinking about the link between unit testing and refactoring have a look:

http://www.artima.com/weblogs/viewpost.jsp?thread=156555

-Marshall