public void Construction()
{
Change fivePence = new Change(5, 1);
Assert.AreEqual(fivePence.Denomination, 5);
Assert.AreEqual(fivePence.Quantity, 1);
// Try a "strange" denomination
Change change = new Change(204, 2);
Assert.AreEqual(change.Denomination, 204);
Assert.AreEqual(change.Quantity, 2);
}
/// <summary>
/// Adds change to the balance of the vending machine
/// </summary>
/// <param name="change">The change to add</param>
public void Add(Change change)
{
if(change == null) throw new ArgumentNullException("change");
// We order the change list from highest denomination to lowest.
// This will simplify certain change algorithms (like greedy)
// where we go from highest to lowest
int index = m_Change.BinarySearch(change, HighToLowChangeComparer.Instance);
if(index < 0)
{
// We've not seen this denomination before so insert it
m_Change.Insert(~index, change);
}
else
{
// Just update the existing item
m_Change[index] = m_Change[index].Add(change);
}
}
/// <summary>
/// Removes change from the balance of the vending machine
/// </summary>
/// <param name="change">The change to add</param>
public void Remove(Change change)
{
if(change == null) throw new ArgumentNullException("change");
int index = m_Change.FindIndex(c => c.Denomination == change.Denomination);
if(index == -1)
{
// If we don't have the specified denomination then flag is as an error
throw new ArgumentException("the vending machine is not holding the specified denomination", "change");
}
Change vendingChange = m_Change[index];
// If we've been asked to remove more of the denomintion than we've got then it's an error
if(change.Quantity > vendingChange.Quantity)
{
throw new ArgumentException("the vending machine is not holding enough of that denomination", "change");
}
int newQuantity = vendingChange.Quantity - change.Quantity;
if(newQuantity == 0)
{
// We've got no more instances of the denomination, so remove it
m_Change.RemoveAt(index);
}
else
{
// We've still got some left, so update it be removing the supplied quantity
m_Change[index] = vendingChange.Add(-change.Quantity);
}
}
public void Construction_InvalidQuantity()
{
Change change = new Change(5, 0);
}
public void Construction_InvalidDenomination()
{
Change change = new Change(0, 10);
}
/// <summary>
/// Creates a new change instance which is the sum
/// of this quanty and the supplied quantiy
/// </summary>
/// <param name="change">The change to add</param>
/// <returns>A new change object</returns>
public Change Add(Change change)
{
if(change == null) throw new ArgumentNullException("change");
if(change.Denomination != m_Denomination) throw new ArgumentException("change has different denomination", "change");
return new Change(m_Denomination, m_Quantity + change.Quantity);
}