Re-work of the contrived example, too hurried

test.cs

[TestFixture]
public class When_a_user_submits_a_form
{
        [Test]
        public void An_email_is_sent_to_his_boss()
        {
             var form = new FormBuilder()
                               .WhichFullyValidates()
                               .ForUser(DefaultUser)
                               .Build();

             var emailEngine = new FakeEmailEngine();

             var formService = new FormService(emailEngine);
             
             formService.Submit(form);
             
             emailEngine.ShouldHaveSentEmail(email => email
                                       .ToUser(DefaultBoss)
                                       .FromUser(DefaultUser);  
        }
 
}