public void DeleteCart_DeletesCart_AndReturnsTrue()
{
var target = new ShoppingCartRepository();
target.AddProductToCart("TestUser", new Product { ProductNumber = "BB-7421" });
var cart = target.GetById("TestUser");
Assert.AreEqual(1, cart.ShoppingCartItems.Count);
var success = target.Delete("TestUser");
Assert.IsTrue(success);
var emptyCart = target.GetById("TestUser");
Assert.AreEqual(0, emptyCart.ShoppingCartItems.Count);
}