WarehouseProduct.cs

public class WarehouseProduct
{
    public string Sku { get; private set; }
    public string Name { get; private set; }
    public string Description { get; private set; }
    public decimal Price { get; private set; }
    public int QuantityOnHand { get; private set; }

    public void SetName(string name)
    {
        if (string.IsNullOrWhiteSpace(name))
        {
            throw new ArgumentException("Name cannot be blank.");
        }

        Name = name;
    }

    public void SetDescription(string description)
    {
        Description = description;
    }

    public void SetPrice(decimal price)
    {
        if (price < 0)
        {
            throw new ArgumentException("Price must be greater than 0.");
        }

        Price = price;
    }

    public void ShipProduct(int quantity)
    {
        if (quantity > QuantityOnHand)
        {
            throw new InvalidDomainException("Ah... we don't have enough product to ship!");
        }

        QuantityOnHand -= quantity;
    }

    public void ReceiveProduct(int quantity)
    {
        QuantityOnHand += quantity;
    }

    public void AdjustInventory(int quantity)
    {
        if (QuantityOnHand + quantity < 0)
        {
            throw new InvalidDomainException("Cannot adjust to a negative quantity on hand.");
        }

        QuantityOnHand += quantity;
    }
}