title: How to unit test this private method?
body: <p>I have a private method as below. 
  How can I unit test this private method?</p>
  
  <p>Is there a pattern that can be adopted to test these kind of private methods?</p>
  
  <pre><code>private ICart GetCart(ICart cart, IEnumerable&lt;ILine&gt; lines)
          {
              var discountedCart = new Cart()
              {
                  Company = cart.Company,
                  DiscountedSubtotal = cart.DiscountedSubtotal,
                  Discounts = cart.Discounts,
                  DiscountValue = cart.DiscountValue,
                  Id = cart.Id,
                  Items = cart.Items,
  
              };
              var validItems = GetValidItems(discountedCart.Items, lines);
              discountedCart.Items.Clear();
              discountedCart.Items = validItems.ToList();
              return discountedCart;
          }
  </code></pre>