InternalsVisibleTo attribute isn't working

Question

I am trying to use the InternalsVisibleTo assembly attribute to make my internal classes in a .NET class library visible to my unit test project. For some reas

Answer 1

Another possibility that may be tricky to track down, depending on how your code is written.

1. You're invoking an internal method defined in X from another assembly Y
2. The method signature uses internal types defined in Z
3. You then have to add [InternalsVisibleTo] in X AND in Z

For example:

// In X
internal static class XType
{
    internal static ZType GetZ() { ... }
}

// In Y:
object someUntypedValue = XType.GetZ();

// In Z:
internal class ZType { ... }

If you have it written like above, where you're not referring to ZType directly in Y, after having added Y as a friend of X, you may be mystified why your code still doesn't compile.

The compilation error could definitely be more helpful in this case.