Unit testing error, could not load file or assembly

Question

I have unit tests for my controllers (around 36). When I run them. I get same error for all the tests

Unable to get type AdminPortal.Tests.Controller_Test.OwnedModuleControllerTest. Error: System.IO.FileLoadException: Could not load file or assembly 'AdminPortal.Tests, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. Signature missing argument. (Exception from HRESULT: 0x801312E3)
File name: 'AdminPortal.Tests, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' ---> System.Runtime.InteropServices.COMException (0x801312E3): Signature missing argument. (Exception from HRESULT: 0x801312E3)
   at System.Reflection.RuntimeAssembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
   at System.Reflection.RuntimeAssembly.nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
   at System.Reflection.RuntimeAssembly.InternalLoadAssemblyName(AssemblyName assemblyRef, Evidence assemblySecurity, RuntimeAssembly reqAssembly, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
   at System.Reflection.RuntimeAssembly.InternalLoadFrom(String assemblyFile, Evidence securityEvidence, Byte[] hashValue, AssemblyHashAlgorithm hashAlgorithm, Boolean forIntrospection, Boolean suppressSecurityChecks, StackCrawlMark& stackMark)
   at System.Reflection.Assembly.LoadFrom(String assemblyFile)
   at Microsoft.VisualStudio.TestPlatform.MSTestFramework.TypeCache.LoadType(String typeName, String assemblyName).

Here is my assemblyinfo class

using System.Reflection;
using System.Runtime.InteropServices;

// General Information about an assembly is controlled through the following 
// set of attributes. Change these attribute values to modify the information
// associated with an assembly.
[assembly: AssemblyTitle("AdminPortal.Tests")]
[assembly: AssemblyDescription("")]
[assembly: AssemblyConfiguration("")]
[assembly: AssemblyCompany("")]
[assembly: AssemblyProduct("AdminPortal.Tests")]
[assembly: AssemblyCopyright("Copyright ©  2013")]
[assembly: AssemblyTrademark("")]
[assembly: AssemblyCulture("")]

// Setting ComVisible to false makes the types in this assembly not visible 
// to COM components.  If you need to access a type in this assembly from 
// COM, set the ComVisible attribute to true on that type.
[assembly: ComVisible(false)]

// The following GUID is for the ID of the typelib if this project is exposed to COM
[assembly: Guid("0412bc0c-30bc-4e0c-9a8d-bcbcd7876702")]

// Version information for an assembly consists of the following four values:
//
//      Major Version
//      Minor Version 
//      Build Number
//      Revision
//
// You can specify all the values or you can default the Revision and Build Numbers 
// by using the '*' as shown below:
[assembly: AssemblyVersion("1.0.0.0")]
[assembly: AssemblyFileVersion("1.0.0.0")]

Solution

It took me a while to track this issue down. The problem was that my test project implicitly referenced a class in another project that wasn't referenced explicitly in my test project. As soon as I added the reference (to the implicitly referenced project) to my test project, and rebuilt, the tests started populating in the Test Explorer again. The link @wal posted was the hint that got me thinking in that direction. From the post it seems this is a Visual Studio / Rhino Mocks issue.

when using generics and/or delegation, make sure all types implicitly referenced by your code are explicitly referenced in the project References.

Source: C# Compiler Bug, or just something obscure and frustrating? ^[alt]

Comments

[Nick.T]

This triggered for me too. Just for others to find a solution: I added the references in the app.config of the Test project