Pex

Microsoft Research has released Pex Power Tool for Visual Studio, which is an automated White box Testing system for .NET. You can find it @ http://research.microsoft.com/en-us/projects/pex/.

Pex uses Moles (another project) which is a lightweight framework for test stubs and detours in .NET that is based on delegates. Moles may be used to detour any .NET method, including non-virtual/static methods in sealed types and is available for free @ http://research.microsoft.com/en-us/projects/moles/