I'm developing a project using BDD/TDD techniques and I'm trying my best to stay the course. A problem I just ran into is unit testing the DefaultModelBinder. I'm using mspec to write my tests. 
I have a class like this that I want to bind to:
public class EmailMessageInput : IMessageInput
    {
        public object Recipient
        {
            get; set;
        }
        public string Body
        {
            get; set;
        }
    }
Here's how I'm building my spec context. I'm building a fake 
form collection and stuffing it into a bindingContext object.
public abstract class given_a_controller_with_valid_email_input : 
            given_a_controller_context
        {
            Establish additional_context = () =>
                               {
                                   var 
form = new FormCollection
                                                  {
                                                      new NameValueCollection
                                                          {
                                                              { "EmailMessageInput.Recipient", "
[email protected]"},
                                                              { "EmailMessageInput.Body", "Test body." }
                                                          }
                                                  };
                                   _bindingContext = new ModelBindingContext
                                                         {
                                                             ModelName = "EmailMessageInput",
                                                             ValueProvider = 
form
                                                         };
                                   _modelBinder = new DefaultModelBinder();
                               };
            protected static ModelBindingContext _bindingContext;
            protected static DefaultModelBinder _modelBinder;
        }
        public abstract class given_a_controller_context
        {
            protected static MessageController _controller;
            Establish context =
                () =>
                    {
                        _controller = new MessageController();
                    };
        }
Finally, my spec throws an null reference exception when I execute .BindModel() from inside one of my specs:
Because of = () => 
                            {
                                _model = _modelBinder.BindModel(_controller.ControllerContext, _bindingContext);
                            };
Any clue what it could be? 
Feel free to ask me for more info, if needed. I might have taken something for granted.