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 possible "gotcha": The name of the friend assembly that you specify in the InternalsVisibleToAttribute must exactly match the name of your friend assembly as shown in the friend's project properties (in the Application tab).

In my case, I had a project Thingamajig and a companion project ThingamajigAutoTests (names changed to protect the guilty) that both produced unsigned assemblies. I duly added the attribute [assembly: InternalsVisibleTo( "ThingamajigAutoTests" )] to the Thingamajig\AssemblyInfo.cs file, and commented out the AssemblyKeyFile and AssemblyKeyName attributes as noted above. The Thingamajig project built just fine, but its internal members stubbornly refused to show up in the autotest project.

After much head scratching, I rechecked the ThingamajigAutoTests project properties, and discovered that the assembly name was specified as "ThingamajigAutoTests.dll". Bingo - I added the ".dll" extension to the assembly name in the InternalsVisibleTo attribute, and the pieces fell into place.

Sometimes it's the littlest things...