NUnit: Unit testing for .NET . This is the second major release of the xUnit based unit testing tool for Microsoft .NET, available at www.nunit.org . It is written entirely in C# and has been completely redesigned to take advantage of many .NET language features, for example custom attributes and other reflection related capabilities.

NMock . A dynamic mockobject-generating framework. Can generate mockobjects at runtime from Interfaces, Abstract Classes, or concrete classes.