What is TDD? Introduction to Test Driven Design (TDD) http://en.wikipedia.org/wiki/Test-driven_development The book I am reading now: Test-Driven Development in Microsoft .Net http://www.amazon.com/gp/product/0735619484/104-6335027-2160757?v=glance&n=283155   In this book, author uses NUnit(http://www.nunit.org/index.php) as the TDD tool. Since I used the Visual Studio Team System, and it has supported TDD. So no need to install NUnit. Just use VSTS. [...]