How to declare a friend assembly?

Question

I have 2 projects in my solution:

1. Assembly (Basic Library)
2. Test Assembly (NUnit)

I had declared the test assembly as friends assembly in first project:

[assembly: InternalsVisibleTo ("Company.Product.Tests")]

Everything was working fine till I realised that I have forgot to setup the solution to sign my assemblies. So created a snk file and setup the visual studio project to sign the first assembly (Basic Library). Now when I compile the first project, I get following error:

Friend assembly reference 'Company.Product.Tests' is invalid. Strong-name signed assemblies must specify a public key in their InternalsVisibleTo declarations.

I tried to extract the public key from my snk file using sn utility but it generates a wired binary file which I am unsure how to use. How can I fix the problem?

Answer 1

You need to sign both assemblies, because effectively both assemblies reference each other.

You have to put the public key in the InternalsVisibleTo attribute. For example, in Protocol Buffers I use:

[assembly:InternalsVisibleTo("Google.ProtocolBuffers.Test,PublicKey="+
"00240000048000009400000006020000002400005253413100040000010001008179f2dd31a648"+
"2a2359dbe33e53701167a888e7c369a9ae3210b64f93861d8a7d286447e58bc167e3d99483beda"+
"72f738140072bb69990bc4f98a21365de2c105e848974a3d210e938b0a56103c0662901efd6b78"+
"0ee6dbe977923d46a8fda18fb25c65dd73b149a5cd9f3100668b56649932dadd8cf5be52eb1dce"+
"ad5cedbf")]

The public key is retrieved by running

sn -Tp path\to\test\assembly.dll

Alternatively, get it from the .snk file:

sn -p MyStrongnameKey.snk public.pk
sn -tp public.pk

Answer 2

I think you need to put in the strong name, which would be something like "Company.Product.Tests, Version=1.0.0.0, Culture=neutral, PublicKeyToken=17135d9fcba0119f". I assume Company.Product.Tests is your assembly name and 17135d9fcba0119f is the public key.

Another way to resolve this problem would be not to use separate assemblies. I usually put the source code and the testing code in the same assembly. I don't know if you have any special concern that you must separate them.

Answer 3

You can directrly get publicKey from assembly which you interest, without magic with sn.exe

<!-- language: c# -->
var assemblyName = Assembly.GetExecutingAssembly().GetName();
Console.WriteLine("{0}, PublicKey={1}",
    assemblyName.Name,
string.Join("", assemblyName.GetPublicKey().Select(m => string.Format("{0:x2}", m))));