When you use Visual Studio 2012, the default Unit Test projects uses MS-Test, the testing framework of Microsoft. However, you can use third-party applications such as NUni, xUnit.NET, and MbUnit as your Unit Test Project. This will allow you to write unit tests using any testing framework of your choice but still use Visual Studio IDE to run tests.
This article explains Unit Test Project with NUnit, how to create a unit test project in Visual Studio 2012, install the Nunit adapter to act as a bridge between Visual Studio and NUnit framework, and ue NUnit within the Unit Test Project.
Read the rest of the tutorial here:Â http://www.codeguru.com/csharp/.net/using-nunit-with-visual-studio-2012-unit-test-projects.htm