Something frustrating I learned today about my favorite Mocking tool today, or at least in version 4.0 that I have installed, it can’t handle anonymous objects in method parameters. This is very depressing in web programming where it doesn’t make much sense to create a static DTO type for every version of a API call.

using Microsoft.VisualStudio.TestTools.UnitTesting;
using Moq;
//Moq version 4.0.10827

namespace AX.Test.Common
{
    public class ExampleAnonObjMockSetup
    {
        public interface IThing
        {
            string DoIt<T>(T it);
        }

        public class Subject
        {
            private readonly IThing _thing;

            public Subject(IThing thing)
            {
                _thing = thing;
            }

            public string Execute()
            {
                var param = new
                {
                    Foo = "bar",
                    Baz = 23
                };
                return _thing.DoIt(param);
            }
        }

        [TestClass]
        public class SubjectTest
        {
            [TestMethod]
            public void Test()
            {
                var mockThing = new Mock<IThing>();
                mockThing.Setup(t => t.DoIt(It.IsAny<object>()))
                    .Returns("expectedResult");

                var subject = new Subject(mockThing.Object);
                var result = subject.Execute();

                Assert.AreEqual("expectedResult", result);
                //Assert.AreEqual failed. Expected:<expectedResult>. Actual:<(null)>
            }
        }
    }
}

I’ve played with this code some more this Gist: https://gist.github.com/thomaslangston/46734b4577d1d3eac8c9d2c331f9e278

Others have reported that this behavior is fixed in Moq 4.1, but I have not yet verified. http://stackoverflow.com/questions/34185691/moq-setup-method-with-generic-anonymous-parameter