Visual Studio 2017 and the new .csproj InternalsVisibleTo

Just in case anyone would like to put InternalsVisibleTo within a .csproj file instead of AssemblyInfo.cs (a possible scenario is to have a naming convention between a project under test and a test project), you can do it like this:

<ItemGroup>
    <AssemblyAttribute Include="System.Runtime.CompilerServices.InternalsVisibleTo">
      <_Parameter1>$(MSBuildProjectName).Test</_Parameter1>
    </AssemblyAttribute>
</ItemGroup>

Having this the following code will be generated

[assembly: System.Runtime.CompilerServices.InternalsVisibleTo("MyProject.Test")]

inside auto-generated AssemblyInfo.cs (e.g. for Debug configuration and .NET Standard 2.0 target)

/obj/Debug/netstandard2.0/MyProject.AssemblyInfo.cs

Additional Info

In case you're on .NET Core 3.1 and this approach isn't working, you may have to explicitly generate assembly info by adding the following to your .csproj file:

<PropertyGroup>
  <!-- Explicitly generate Assembly Info -->
  <GenerateAssemblyInfo>true</GenerateAssemblyInfo>
</PropertyGroup>

To clarify Hans Passant's comment above, you simply have to add InternalsVisibleTo to any cs file in your project. For example, I created an AssemblyInfo.cs file in the root of the project and then added the following content (only):

using System.Runtime.CompilerServices;

[assembly: InternalsVisibleTo("DynamicProxyGenAssembly2, PublicKey=<ADD_KEY_HERE>")]

As of .NET 5 this actually works once added to your csproj:

<ItemGroup>
  <InternalsVisibleTo Include="YourProject.Tests.Unit" />
</ItemGroup>

Work and discussion around this feature can be seen on this PR on dotnet's GitHub repo.

Visual Studio 2017 and the new .csproj InternalsVisibleTo

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