Charles,
"you want test your code without running Revit ?" -Correct. That is exaclty what I want. And to be honest, it is rather crucial for efficient coding and ensuring high quality of the code.
Visual Studio Enterprise provides the opportunity of creating fake assemblies of refered dlls (see pics). This should enable unit testing of API-dependentg code, if RevitAPI.dll did not require Revit to run. When i try to run a simple test, it throws an exception.