Hi Alexander
The build agent invokes MSTest.exe command line tool during a build to run tests. MSTest.exe doesn't recognize NUnit test assemblies. So MSTest.exe doesn't execute any test methods.
To integrate NUnit to a team build, please take a look at
http://nunit4teambuild.codeplex.com/. I haven't tried it yet. Hope it can help you solve this problem.
Please remember to mark the replies as answers if they help and unmark them if they provide no help.
Send us any feedback you have about the help from MSFT at
fbmsdn@microsoft.com.