In the 5 years since the release of NUnit 2.0, there have been millions of lines of code written using the various unit testing frameworks for .NET. About a year ago it became clear to myself and Brad Wilson that there were some very clear patterns of success (and failure) with the tools we were using for writing tests. Rather than repeating guidance about "do X" or "don't do Y", it seemed like it was the right time to reconsider the framework itself and see if we could codify some of those rules.
Additionally, the .NET framework itself has evolved a lot since its v1 release in early 2002. Being able to leverage some of the new framework features can help us write clearer tests.
[...] While any one of these reasons would not necessarily have been sufficient to create a new testing framework, the combination of them all made us want to undertake a new project: xUnit.net.
Download: xUnit.net 1.0
xUnit.net, .NET Framework, Software, Download