MOQ 4.0: The type initializer for 'Moq.Mock`1' threw an exception

Question

I'm getting the exception

The type initializer for 'Moq.Mock`1' threw an exception.

using Moq 4.0 I've checked around on a couple of forums and they allude to using the Moq-NoCastle version. I've tried both this and version in the Moq folder. Both with the same result.

I've got a solution with 2 projects, one for my interface, one for my tests. My main project has 2 files:

IMyInterface.cs:

using System;

namespace Prototype
{
    public interface IMyInterface
    {
        int Value { get; set; }
        void ProcessValue();
        int GetValue();
    }
}

My program.cs file has just the default code that's generated with the project.

My test project has a single file for my dummy test - TestProgram.cs

using System;
using NUnit.Framework;
using Moq;

namespace Prototype.UnitTests
{
    [TestFixture]
    public class TestProgram
    {
        Mock<IMyInterface> mock;

        [TestFixtureSetUp]
        void TestSetup()
        {
            mock = new Mock<IMyInterface>();
            mock.Setup(x => x.GetValue()).Returns(2);
        }

        [Test]
        public void RunTest()
        {
            IMyInterface obj = mock.Object; /* This line fails */
            int val = obj.GetValue();
            Assert.True(val == 2);
        }
    }
}

According to the documentation all is good and proper, and it compiles nicely. The problem comes when I try to run the test. It gets to the line marked above and crashes with the exception:

The type initializer for 'Moq.Mock`1' threw an exception.

I can't see what's going wrong here, can anyone shed some light on it?

Answer 1

This occurred to me when I updated the Castle.Core NuGet Package to the version 4.0.0. Something changed that is does not work properly with latest Moq (v4.5.30) at this moment.

I solved this by going back to the Castle.Core version 3.3.3.