[SOLVED] Need to Stub a Function that takes a Func<> as a Parameter

Need to Stub a Function that takes a Func<> as a Parameter

I have a method on my data access layer that can take any function as search criteria and run this against our Entity Framework entities. I am trying to create unit tests using Rhino Mocks on the business layer, but this calls the DAL method. When I try to create a stub for this search method, I cannot seem to get it to run correctly. I have the following method that needs to be stubbed:

IQueryable<T> AllSearchBy<T>(params Expression<Func<T, bool>>[] search) where T : class;

I cannot seem to find a generic expression to use such as Arg.Is.Anything for functions, so I tried setting up my own. I have the following that should return the first value in my _fakeObjs if the Id is 1 and should return a null if the Id is 0 (two separate tests):

myObjId = 1;  // or 0 for returning a null
System.Linq.Expressions.Expression<Func<MyObj, bool>> myFunc = (a => a.Id == objId); 
IRepository repositoryMock = MockRepository.GenerateMock<IRepository>();
repositoryMock.Stub(x => x.AllSearchBy<MyObj>(myFunc)).Return(_fakeObjs.Where(x => x.Id == myObjId));

However, I am getting the following errors. For the one that should return an object (value = 1):

Message: Test method
NS.MyApp.Test.ObjTest.SearchById_ReturnsObj threw exception:
System.ArgumentNullException: Value cannot be null.
Parameter name: source

For the one that should return a null (value = 0):

Message: Test method
NS.MyApp.Test.ObjTest.SearchById_ReturnsNull threw exception:
Rhino.Mocks.Exceptions.ExpectationViolationException:
IRepository.AllSearchBy<NS.EF.MyObj>([]); Expected #1, Actual #0.

What do I need to do to set up a parameter to pass into the AllSearchBy in my repository?

Thanks in advance for any help!!

Solution

What if you try to pass following as an argument instead of current myFunc:

Arg<Expression<Func<MyObj, bool>>[]>.Is.Anything