The following page describes how to make internal types visible to the generated fakes assembly. http://msdn.microsoft.com/en-us/library/hh708916.aspx#bkmk_internal_types
Which says:
The Fakes code generator will generate shim types and stub types for types that are visible to the generated Fakes assembly. To make internal types of a shimmed assembly visible to Fakes and your test assembly, add
InternalsVisibleToAttribute
attributes to the shimmed assembly code that gives visibility to the generated Fakes assembly and to the test assembly.
So you need an InternalsVisibleToAttribute
that grants your test assembly access to the internal types of the target assembly. In other words:
[assembly: InternalsVisibleTo("TargetAssembly.Fakes")]
[assembly: InternalsVisibleTo("TestAssembly")]