ShoppingCart.WithIntent.cs

public class ShoppingCart
{
    public IList<CartItem> Items { get; set; }
    public decimal CartTotal { get { return Items.Sum(item => item.Total); } }

    public void AddCartItemAndDoTracking(CartItem item)
    {
        AddOrIncreaseQuantityFor(item);
        TrackForLoggingDebuggingAndCustomerServiceCenter(CustomerAction.CartItemAddedToCart);
    }
    
    private void AddOrIncreaseQuantityFor(CartItem addedItem)
    {
        if (CartContainsStockKeepingUnit(addedItem.StockKeepingUnit))
        {
            var itemInCart = Items.First(inCart => inCart.StockKeepingUnit == addedItem.StockKeepingUnit);
            itemInCart.Quantity += addedItem.Quantity;
        }
        else
        {
            Items.Add(item);
        } 
    }
    
    bool CartContainsStockKeepingUnit(StockKeepingUnit sku)
    {
        return Items.Any(x => x.Sku == sku)
    }
    
    
    void TrackForLoggingDebuggingAndCustomerServiceCenter(Action action)
    {
        CustomerTrackingService.SignalTotalInShoppingCartUpdated(action, CartTotal);
    }
}