MockDataHelper.cs

    public class DataMockHelpers
    {
        public Mock<IQeraUnit> GetMockUnit()
        {
            var unit = new Mock<IQeraUnit>();
            return unit;
        }

        public Mock<TRepo> MockRepo<TRepo, TEntity>(List<TEntity> seedData = null, bool callBase = false, MockBehavior behavior = MockBehavior.Default) 
            where TRepo : class, IRepo<TEntity>
            where TEntity : class
        {
            var repo = new Mock<TRepo>(behavior) { CallBase = callBase };
            var backingStore = seedData ?? new List<TEntity>();

            repo.Setup(x => x.All()).Returns(backingStore.AsQueryable());
            repo.Setup(x => x.Insert(It.IsAny<TEntity>())).Callback((TEntity item) => backingStore.Add(item));
            repo.Setup(x => x.Single(It.IsAny<Expression<Func<TEntity, bool>>>())).Returns((Expression<Func<TEntity, bool>> filter) => backingStore.AsQueryable().FirstOrDefault(filter));
            repo.Setup(x => x.Delete(It.IsAny<TEntity>())).Callback((TEntity item) => backingStore.Remove(item));

            return repo;
        }
    }