public void ShouldGetAllHandlers(
[Frozen] Mock <IServiceProvider> services,
MessageHandlerFactory sut)
{
var handlers = Fixture.CreateMany <IMessageHandler <TestMessage> >();
services.Setup(x => x.GetService(typeof(IEnumerable <IMessageHandler <TestMessage> >)))
.Returns(handlers);
var result = sut.GetHandlersFor <TestMessage>();
Assert.Equal(handlers, result);
}