Mocking IObjectSet<T> with Rhino Mocks

Question

Is there a way of using Rhino Mocks to generate Stub for an IObjectSet<T> ?

What is am after is something like the following code:

var context = MockRepository.GenerateMock <IContext>();
//generate stub
var mockProjectObjectSet = MockRepository.GenerateStub<IObjectSet<Project>>();
TestObjectSets.GenerateFakeProjectList(mockProjectObjectSet);
context.Expect(p => p.Projects).Return(mockProjectObjectSet);
var projectRepository = new ProjectRepository(context);

In the GenerateFakeProjectList static helper method, I am simply creating the objects of the type specified and adding them to the stub via the AddObject method on the IObjectSet :

public static IObjectSet<Project> GenerateFakeProjectList(IObjectSet<Project> projectsObjectSet)
{     
   projectsObjectSet.AddObject(new Project()
   {
     Categories = null,
     DateCreated = DateTime.Now.AddDays(-10),
    .......

Answer 1

I know I'm late to this party, but here's a simple implementation of IObjectSet<T> that I've used before. I forget where I got it from:

public class MockObjectSet<T> : IObjectSet<T> where T : class {
        readonly List<T> _container = new List<T>();

        public void AddObject(T entity) {
            _container.Add(entity);
        }

        public void Attach(T entity) {
            _container.Add(entity);
        }

        public void DeleteObject(T entity) {
            _container.Remove(entity);
        }

        public void Detach(T entity) {
            _container.Remove(entity);
        }

        public IEnumerator<T> GetEnumerator() {
            return _container.GetEnumerator();
        }

        IEnumerator IEnumerable.GetEnumerator() {
            return _container.GetEnumerator();
        }

        public Type ElementType {
            get { return typeof(T); }
        }

        public System.Linq.Expressions.Expression Expression {
            get { return _container.AsQueryable<T>().Expression; }
        }

        public IQueryProvider Provider {
            get { return _container.AsQueryable<T>().Provider; }
        }
    }

Answer 2

I'd use a concrete instance, or a simple fake. That interface has a small number of methods and the implementation appears trivial. Mocking that interface just adds unnecessary complexity.

Answer 3

Since you're mocking an interface, there's no actual code to all. Just set up a stub for your interface and then stub out the Projects property to return what you want (I assume Projects is a property, but you didn't include a definition of the Project class).

Something like this should work:

var stubSet = MockRepository.GenerateStub<IObjectSet<Project>>();
stubSet.Stub(s => s.Projects).Return(new[]
                                                {
                                                    new Project {Categories = null},
                                                    new Project {Categories = "abc"}
                                                });