Problem mocking DbSet and using Include about entityframework-classic HOT 12 CLOSED

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.Entity;
using System.Drawing;
using System.Linq;
using System.Linq.Expressions;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using Castle.Core.Logging;
using Moq;

namespace Z.Lab.Request_Mock
{
    public partial class Form_Request_QueryFilter_Interface : Form
    {
        public static int ApplicationTenantID = 1;

        public Form_Request_QueryFilter_Interface()
        {
            var customer = new Customer();
            var order = new Order() { Name = "blabla" };
            customer.Orders.Add(order);

            var customers = new List<Customer>
            {
                customer
            }.AsQueryable();

            var orders = new List<Order>
            {
                order
            }.AsQueryable();

            var mockContext = new Mock<EntityContext>(MockBehavior.Loose);

            var mockCustomersSet = new Mock<DbSet<Customer>>();
            mockCustomersSet.As<IQueryable<Customer>>().Setup(m => m.Provider).Returns(customers.Provider);
            mockCustomersSet.As<IQueryable<Customer>>().Setup(m => m.Expression).Returns(customers.Expression);
            mockCustomersSet.As<IQueryable<Customer>>().Setup(m => m.ElementType).Returns(customers.ElementType);
            mockCustomersSet.As<IQueryable<Customer>>().Setup(m => m.GetEnumerator()).Returns(customers.GetEnumerator());
            mockCustomersSet.Setup(m => m.Include("Orders")).Returns(mockCustomersSet.Object);

            var mockOrdersSet = new Mock<DbSet<Order>>();
            mockOrdersSet.As<IQueryable<Order>>().Setup(m => m.Provider).Returns(orders.Provider);
            mockOrdersSet.As<IQueryable<Order>>().Setup(m => m.Expression).Returns(orders.Expression);
            mockOrdersSet.As<IQueryable<Order>>().Setup(m => m.ElementType).Returns(orders.ElementType);
            mockOrdersSet.As<IQueryable<Order>>().Setup(m => m.GetEnumerator()).Returns(orders.GetEnumerator());

            mockContext.SetupGet(c => c.Customers).Returns(mockCustomersSet.Object);
            mockContext.SetupGet(c => c.Orders).Returns(mockOrdersSet.Object);

            var customerList = mockContext.Object.Customers.Include("Orders").Select(p => p).ToList();
        }

        public class EntityContext : DbContext
        {
            public EntityContext() : base(My.ConnectionString)
            {
            }

            public virtual DbSet<Customer> Customers { get; set; }
            public virtual DbSet<Order> Orders { get; set; }

        }

        public class Customer
        {
            public Customer()
            {
                Orders = new List<Order>();
            }

            public int CustomerID { get; set; }
            public string Name { get; set; }
            public string Description { get; set; }
            public Boolean IsDeleted { get; set; }
            public virtual List<Order> Orders { get; set; }
        }

        public class Order
        {
            public int OrderID { get; set; }
            public int CustomerID { get; set; }
            public string Name { get; set; }
            public string Description { get; set; }
            public Boolean IsDeleted { get; set; }
        }
    }
}

var customerList = mockContext.Object.Customers.Include("Orders").ToList();