Why does my attempt to mock EntityFramework fail at compile time

Hi All,

Can someone please tell me why attempting to mock entityFramwork throws a compile time error on this line?

            Isolate.WhenCalled(() => contextHandle.LPRProvinceCodes.Find(0)).WillReturnCollectionValuesOf(pcodes.AsQueryable());

The error is: *** Method System.Data.Entity.DbSet`1[PlateTech.Shared.Models.LPRProvinceCode].Find returns PlateTech.Shared.Models.LPRProvinceCode. Can only use WillReturnCollectionValuesOf() on enumerable types.

Here is my test code:

        [TestMethod, Isolated]

        public void CheckpointTest2()

        {

            LPRInterfaceMessage lprMsg = new LPRInterfaceMessage()

            {

                   ... msg properties go here

            };

            Object[] lprsMessages = new Object[] { lprMsg };

            // Mock the EF context

            var contextHandle = Isolate.Fake.AllInstances<EFContext>(Members.CallOriginal);

            IList<LPRProvinceCode> pcodes = new List<LPRProvinceCode>()

            {

                new LPRProvinceCode()

                {

                    LPRCountryCodeId = 999,

                    ProvinceCode = \\\"999\\\",

                    ProvinceName = \\\"Unknown\\\"

                }

            };

            Isolate.WhenCalled(() => contextHandle.LPRProvinceCodes.Find(0)).WillReturnCollectionValuesOf(pcodes.AsQueryable());

            LPRInterface lpi = new LPRInterface();

            lpi.ThreadedAddLPREvent(lprsMessages);

        }

    }

here is the EF call that I am trying to mock:

public string FindProvinceByCode(string provinceCode)

        {

            if (int.TryParse(provinceCode, out int provinceCodeValue))

            {

                var results = _context.LPRProvinceCodes.Find(provinceCodeValue);

                if (results != null)

                {

                    return results.ProvinceName;

                }

            }

            return string.Empty;

        }