Question

I have the following code in my function to retrieve the data from the database:

var oldFareSpecification = new ObservationOnOrBeforeDateSpecification(previousOutboundDate));

var oldFare = _fareRepository.Find(oldFareSpecification).SingleOrDefault();

the specification is:

public class ObservationOnOrBeforeDateSpecification : Specification<Fare>
    {
        public ObservationOnOrBeforeDateSpecification(DateTime date)
        : base(fh => EntityFunctions.DiffDays(fh.ObservationTS, date) >= 0)
    {
    }
    }

which uses System.Data.Entity.
Repository is

Repository<TEntity> : IRepository<TEntity>
private readonly DbContext _context;
        private readonly DbSet<TEntity> _entitySet;
public IEnumerable<TEntity> Find(ISpecification<TEntity> criteria)
        {
            return criteria.SatisfyingEntitiesFrom(_entitySet).AsEnumerable();
        }

it works fine, but when I try to Moq repository in test class and make calls to repository returning results of queries on my fake objects, I get an exception:
Function can be called only from LINQ to entities (or very similar – I get it in other language : p).

My test class make database returning fake results this way:

var faresRepository = Fixture.Freeze<Mock<IRepository<DAL.Fare>>>();
faresRepository.Setup(
                fhr => fhr.Find(It.IsAny<ISpecification<Fare>>())).Returns(
                (ISpecification<Fare> spec) => spec.SatisfyingEntitiesFrom(fares.AsQueryable()));

and now my question is how can I code specification that compares the difference in days and works fine called from the code normally and on the Mocked repository. By right compare I mean here, that difference between 2013.01.16 23:55:34 and 2013.01.17 01:55:34 in days returns 1.

Answer 1

Solution:

** Only way to do it is to create a queue which returns fake results each time specific method (here .Find) is called. not exactly what I would like to achieve, but at least works. so here it is:

    var faresHistoryRepository = Fixture.Freeze<Mock<IRepository<DAL.FareHistory>>>();

    var fareHistoryResults = new Queue<List<FareHistory>>();

    var fareHistories = new List<DAL.FareHistory>();
    FareHistory fh1 = new FareHistory { FareHistoryId = fareHistoryId + 1, FareId = fareId, ObservationTS = date.AddDays(-1), StatusId = (int)DAL.Enum.Status.Active };
    fareHistories.Add(fh1);
    fh1 = new FareHistory { FareHistoryId = fareHistoryId + 4, FareId = fareId, ObservationTS = date.AddDays(-4), StatusId = (int)DAL.Enum.Status.Active };
    fareHistories.Add(fh1);
    fh1 = new FareHistory { FareHistoryId = fareHistoryId + 5, FareId = fareId, ObservationTS = date.AddDays(-5), StatusId = (int)DAL.Enum.Status.Active };
    fareHistories.Add(fh1);
    fareHistoryResults.Enqueue(fareHistories); // fare histories

    var fareHistoriesSample = new List<DAL.FareHistory>();
    fh1 = new FareHistory { FareHistoryId = fareHistoryId + 6, FareId = oldFareId,
 ObservationTS = depDate.AddDays(-fullDaysDifference), StatusId = (int)DAL.Enum.Status.Active };
    fareHistoriesSample.Add(fh1);
        fh1 = new FareHistory { FareHistoryId = fareHistoryId + 7, FareId = oldFareId,
     ObservationTS = depDate.AddDays(-15), StatusId = (int)DAL.Enum.Status.Active };
        fareHistoriesSample.Add(fh1);
        fh1 = new FareHistory { FareHistoryId = fareHistoryId + 8, FareId = oldFareId,
     ObservationTS = depDate.AddDays(-16), StatusId = (int)DAL.Enum.Status.Active };
                    fareHistoriesSample.Add(fh1);

        fareHistoryResults.Enqueue(fareHistoriesSample); // fareHistoriesSample

        faresHistoryRepository.Setup(
                            fhr => fhr.Find(It.IsAny<ISpecification<FareHistory>>
    ())).Returns(()=>fareHistoryResults.Dequeue());