How are NUnit assemblies appearing in VS "Add Reference" dialog?

Question

So after installing NUnit, the assemblies (nunit.framework, etc.) now appear in the References > Add Reference dialog, but they're not in the %WINDIR%\Microsoft.NET\Framework\v2.0.50727 dir and there is no NUnit registry entry for the Assembly Path (i.e. HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft.NETFramewokr\AssemblyFolder). There's also no automatic entries created in the project properties Reference Paths for the NUnit install directory. How the heck are they appearing in the "Add Dialog"?!?! I thought the mentioned way were the only ways assemblies could appear in "Add Reference".

Answer 1

Strange, [HKEY_CURRENT_USER\SOFTWARE\Microsoft.NETFramework\AssemblyFolders] should be the only thing driving this.

Perhaps this snippet from this page is relevant?

If you install the .NET Framework 3.0 Service Pack 1 (SP1), the following registry subkey is added:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\AssemblyFolders\v3.0

If you install the .NET Framework 3.5, the following registry subkey is added:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\AssemblyFolders\v3.5

Answer 2

On my install of NUnit I have a registry key

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\AssemblyFolders\NUnit 2.4.3

It seems to be the driver of this behaviour on my computer. Once I removed that key the references did not appear.

Answer 3

I dug deeper into this at the weekend. Reproduced verbatim from my blog:

Why is NUnit not in the GAC? (or Why does [assembly X] not appear in Visual Studio's Add Reference dialog?)

Because Visual Studio doesn’t look for references in the GAC:

• http://blogs.msdn.com/msbuild/archive/2007/04/12/new-reference-assemblies-location.aspx
• http://blogs.msdn.com/junfeng/archive/2004/03/22/93708.aspx

This is by design.

You can either add your files explicitly, which doesn’t work if other people in your team have installed the files somewhere else, for example C:\Program Files\NUnit 2.4.6 vs. C:\Program Files\NUnit-2.4.6. Or (more specifically, because this is the problem I was having this morning) C:\Program Files\NUnit 2.4.6 vs. C:\Program Files (x86)\NUnit 2.4.6. Note the (x86) – my home PC is (as of last weekend) running Vista Ultimate x64.

You have a couple of options:

• If your assemblies don’t already have homes, you can put them in the VS PublicAssemblies folder: http://blogs.msdn.com/csharpfaq/archive/2004/10/20/245239.aspx
• If they already have homes, you can add them to the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\AssemblyFolders registry key: http://support.microsoft.com/?kbid=306149.
• If you’re developing assemblies for other developers to use (i.e. you’re Microsoft or a development tool vendor), you can put these in a subdirectory of C:\Program Files\Reference Assemblies directory, and then add that to the AssemblyFolders registry key.

This means that your project files will reference the assembly by name (i.e. name, version, public key token, all that jazz), and it won’t matter where it’s actually installed on your PC.

Note, however, that this doesn’t work as-is on 64-bit, because Visual Studio is a 32-bit application. You actually need to register your stuff under HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\.NETFramework\AssemblyFolders, and you should probably register under both.

There are also corresponding HKEY_CURRENT_USER variants of those keys, but (since that roams), it’s not much use (because the paths are usually relative to the machine, anyway).