Visual Studio 2017 and the new .csproj InternalsVisibleTo

Question

Where do I put InternalsVisibleTo from AssemblyInfo in the new Visual Studio 2017 .csproj project file?

Solution 1

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>")]

Solution 2

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>

Solution 3

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.

Comments

[Daniel Gimenez]

This technique is very useful. If you have multiple projects you can use a directory.build.props file in the solution root and have it apply to all of your projects.

[julealgon]

Is there any official documentation for this approach that you could link to?

[Ivan Zaruba]

Not sure this approach is documented since it is rather customization than common practice. But if you would like to know how this works, please refer to the Microsoft.NET.GenerateAssemblyInfo.targets file github.com/dotnet/sdk/blob/release/2.1/src/Tasks/…

[yurislav]

This should be the accepted answer, as the question states to add InternalsVisibleTo to .csproj file.

[Cocowalla]

This might be obvious, but it might be worth nothing that this won't work if you have GenerateAssemblyVersionAttribute set to false

[Andy Danger Gagne]

Alternative to ($MSBuildProjectName) is $(AssemblyName) in the event your project name is different than your assembly.

[dashesy]

No need to use PublicKeyin this case?

[Ivan Zaruba]

@dashesy, this approach changes nothing as if you have used an attribute. You will need a <_Parameter1>BlaBla, PublicKey=Bla</_Parameter1> for a signed assembly.

[void.pointer]

If you do end up adding this to your Directory.Build.props files, you want to make sure it's excluded from test projects. The following condition on my ItemGroup worked for me: <ItemGroup Condition="!$(ProjectName.EndsWith('.Tests'))">. My test naming convention for a project called Foo is Foo.Tests. This condition is built with that in mind.