public void MultiplePresentInAndMultiplePresentOutWillBeInvalid()
{
ExchangeCheckSum subject = new ExchangeCheckSum();
subject.updatePresentsIn();
subject.updatePresentsIn();
subject.updatePresentsIn();
subject.updatePresentsOut();
subject.updatePresentsOut();
subject.updatePresentsOut();
Assert.AreEqual(false, subject.isValid());
VerifyDiagnosticMessage(3, 3, subject.DiagnosticMessage());
}
public void OnePresentInAndOnePresentOutWillBeValid()
{
ExchangeCheckSum subject = new ExchangeCheckSum();
subject.updatePresentsIn();
subject.updatePresentsOut();
Assert.AreEqual(true, subject.isValid());
Assert.AreEqual("correct", subject.DiagnosticMessage());
}