CQRS - generic handlers

gistfile1.txt

using FluentAssertions;
using MediatR;
using NUnit.Framework;
using StructureMap.Graph;
using System;
using System.IO;
using System.Linq;
using System.Security.Cryptography.X509Certificates;
using StructureMap;
using StructureMap.Graph.Scanning;
using Container = StructureMap.Container;

namespace MediatorTests
{
    [TestFixture]
    public class UnitTest1
    {
        public class HomeItem : IItem
        {
            
        }

        [Test]
        public void ShouldResolveGenericHandler()
        {
            var container = new Container(cfg =>
            {
                cfg.Scan(scanner =>
                {
                    scanner.TheCallingAssembly();
                    scanner.IncludeNamespaceContainingType<HomeItem>();
                    scanner.AddAllTypesOf(typeof(IRequestHandler<,>));
                    scanner.With(new AddRequestHandlersWithGenericParametersToRegistry());
                    scanner.WithDefaultConventions();
                });
                cfg.For<SingleInstanceFactory>().Use<SingleInstanceFactory>(ctx => t => ctx.GetInstance(t));
                cfg.For<MultiInstanceFactory>().Use<MultiInstanceFactory>(ctx => t => ctx.GetAllInstances(t));
                cfg.For<IMediator>().Use<Mediator>();
            });

            var mediator = container.GetInstance<IMediator>();
            Console.Write(container.WhatDoIHave());
            var response = mediator.Send(new CreateItemCommand<HomeItem>());

            response.Should().NotBeNull();
        }

    }

    public class CreateItemCommand<T> : IRequest<T> where T: IItem
    {

    }

    public class CreateItemCommandHandler<T> : IRequestHandler<CreateItemCommand<T>, T> where T : IItem
    {
        public T Handle(CreateItemCommand<T> message)
        {
            return Activator.CreateInstance<T>();
       }
    }

    public class AddRequestHandlersWithGenericParametersToRegistry : IRegistrationConvention
    {
        public void ScanTypes(TypeSet types, Registry registry)
        {
            foreach (var concreteClass in types.FindTypes(TypeClassification.Concretes))
            {
                if (concreteClass.GetInterfaces().Contains(typeof(IItem)))
                {
                    var genericCommand = typeof (CreateItemCommand<>).MakeGenericType(concreteClass);
                    var interfaceHandlerType = typeof(IRequestHandler<,>).MakeGenericType(genericCommand, concreteClass);
                    var concreteHandlerType = typeof(CreateItemCommandHandler<>).MakeGenericType(concreteClass);
                    registry.For(interfaceHandlerType).Use(concreteHandlerType);
                }
            }
        }
    }

    public interface IItem
    {
    }
}

TODO: currently only adds commands that implement CreateItemCommand - would be better if this found any commands that take a type of