1> The readers
2> If logic.

If a requirement came in for the die, then and only then would I try to deal with those change points.

note: Originally I had the if logic in the Coin Reader class.

Nice. What you just did was partition the complexity.

Now, I’ll ask you a question, is it a good partition? If so, why? (evil grin)

[TestFixture]
public class ComplexityTest
{
[Test]
public void Tail()
{
CoinReader pennyReader = CoinReader.PennyReader;

IList readerList = new ArrayList();

readerList.Add(pennyReader);

Display display = new Display(readerList);

RandomService.value = true;
Assert.AreEqual(“Penny is Tails\r\n”, display.GetMessage());
}

[Test]
public void Head()
{
CoinReader dimeReader = CoinReader.DimeReader;

IList readerList = new ArrayList();

readerList.Add(dimeReader);

Display display = new Display(readerList);

RandomService.value = true;
Assert.AreEqual(“Dime is Tails\r\n”, display.GetMessage());
}

[Test]
public void AllTails()
{
CoinReader pennyReader = CoinReader.PennyReader;
CoinReader dimeReader = CoinReader.DimeReader;

IList readerList = new ArrayList();

readerList.Add(pennyReader);
readerList.Add(dimeReader);

Display display = new Display(readerList);

RandomService.value = true;
Assert.AreEqual(“Penny is Tails\r\nDime is Tails\r\n”, display.GetMessage());
}

[Test]
public void AllHeads()
{
CoinReader pennyReader = CoinReader.PennyReader;
CoinReader dimeReader = CoinReader.DimeReader;

IList readerList = new ArrayList();

readerList.Add(pennyReader);
readerList.Add(dimeReader);

Display display = new Display(readerList);

RandomService.value = false;
Assert.AreEqual(“Penny is Heads\r\nDime is Heads\r\n”, display.GetMessage());
}

[Test]
public void AllSuperHeads()
{
CoinReader pennyReader = CoinReader.PennyReader;
CoinReader dimeReader = CoinReader.DimeReader;
CoinReader quarterReader = CoinReader.QuarterReader;

IList readerList = new ArrayList();

readerList.Add(pennyReader);
readerList.Add(dimeReader);
readerList.Add(quarterReader);

Display display = new Display(readerList);

RandomService.value = false;
Assert.AreEqual(“Penny is Heads\r\nDime is Heads\r\nQuarter is Heads\r\n”, display.GetMessage());
}
}

public class RandomService
{
public static bool value;

public bool GetRandom()
{
return value;
}
}

public class CoinReader
{
private string readerType;
private bool coinStatus;

private RandomService randomService;

private CoinReader(string type, RandomService service)
{
readerType = type;
randomService = service;
}

public void Read()
{
coinStatus = randomService.GetRandom();
}

public string GetReaderType()
{
return readerType;
}

public bool GetStatus()
{
return coinStatus;
}

public static CoinReader DimeReader = new CoinReader(“Dime”, new RandomService());
public static CoinReader PennyReader = new CoinReader(“Penny”, new RandomService());
public static CoinReader QuarterReader = new CoinReader(“Quarter”, new RandomService());
}

public class Display
{
private IList readerList = null;

public Display(IList list)
{
readerList = list;
}

public string GetMessage()
{
string message = string.Empty;
string status = string.Empty;

foreach (CoinReader reader in readerList)
{
reader.Read();
status = reader.GetStatus() ? “Tails” : “Heads”;
message += reader.GetReaderType() + ” is ” + status + Environment.NewLine; ;
}
return message;
}
}