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 reason, I keep getting an error message that says:

'MyClassName' is inaccessible due to its protection level

Both assemblies are signed and I have the correct key listed in the attribute declaration. Any ideas?

Answer 1

Are you absolutely sure you have the correct public key specified in the attribute? Note that you need to specify the full public key, not just the public key token. It looks something like:

[assembly: InternalsVisibleTo("MyFriendAssembly, PublicKey=0024000004800000940000000602000000240000525341310004000001000100F73 F4DDC11F0CA6209BC63EFCBBAC3DACB04B612E04FA07F01D919FB5A1579D20283DC12901C8B66 A08FB8A9CB6A5E81989007B3AA43CD7442BED6D21F4D33FB590A46420FB75265C889D536A9519 674440C3C2FB06C5924360243CACD4B641BE574C31A434CE845323395842FAAF106B234C2C140 6E2F553073FF557D2DB6C5")] 

It's 320 or so hex digits. Not sure why you need to specify the full public key - possibly with just the public key token that is used in other assembly references it would be easier for someone to spoof the friend assembly's identity.