public void ReturnsOrderWithOrderedItem()
    {
        var spec = new eShopWeb.ApplicationCore.Specifications.CustomerOrdersWithItemsSpecification(_buyerId);

        var result = GetTestCollection()
                     .AsQueryable()
                     .FirstOrDefault(spec.WhereExpressions.FirstOrDefault().Filter);

        Assert.NotNull(result);
        Assert.NotNull(result.OrderItems);
        Assert.Equal(1, result.OrderItems.Count);
        Assert.NotNull(result.OrderItems.FirstOrDefault().ItemOrdered);
    }
        public void ReturnsAllOrderWithAllOrderedItem()
        {
            var spec = new eShopWeb.ApplicationCore.Specifications.CustomerOrdersWithItemsSpecification(_buyerId);

            var result = GetTestCollection()
                         .AsQueryable()
                         .Where(spec.Criterias.FirstOrDefault())
                         .ToList();

            Assert.NotNull(result);
            Assert.Equal(2, result.Count);
            Assert.Equal(1, result[0].OrderItems.Count);
            Assert.NotNull(result[0].OrderItems.FirstOrDefault().ItemOrdered);
            Assert.Equal(2, result[1].OrderItems.Count);
            Assert.NotNull(result[1].OrderItems.ToList()[0].ItemOrdered);
            Assert.NotNull(result[1].OrderItems.ToList()[1].ItemOrdered);
        }