How to make your internal classes accessible to your unit tests in .NET

Here a little tip I’ve found while reading Moq source code. If you want to test some internal classes of your library, you don’t have to make your classes public in order to be visible in your test assembly (like how I was doing untill now…)

The trick is to add this little line into your assembly properties (AssemblyInfo.cs)

[assembly: InternalsVisibleTo("NameOfYourTestAssembly")]

Now all class with the internal visibility will be accessible to your unit tests. For private visibility, one solution is to use reflection or just look on Google 😉