Unit Test Internal Members

18 Jan

Applies to .Net application in Visual Studio 2010 and up.

Say I have C# project (call it QC project). In the project, I have class that has internal member(s) like this:

namespace QC
    public class PersonService
        public bool PromotePerson(string userName)

        internal bool FindPerson(string userName)

For unit test, I’d created separate project (call it QCTest project). Because internal members can only be accessed in same assembly, I won’t be able to invoke `QC.PersonService.FindPerson(string userName)` method from QCTest project.

To overcome this issue, in `AssemblyInfo.cs` of project being tested (in my case, QC project), simply add

[assembly: InternalsVisibleTo("QCTest")]

After rebuilding my solution, I am able to access `QC.PersonService.FindPerson(string userName)` in my QCTest project.

As an added bonus, if you use mock library like Moq or Rhino and try to mock internal members, you most likely need to add:

[assembly: InternalsVisibleTo("DynamicProxyGenAssembly2")]

What is `DynamicProxyGenAssembly2` ?

DynamicProxyGenAssembly2 is a temporary assembly built by mocking systems that use CastleProxy like Moq or NSubsitute. It is generated when the mock is needed and disposed of after the tests are finished.


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Posted by on January 18, 2019 in General


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