public void AddCoin()
{
int originalCount = testCoinBank.Coins[5];
testCoinBank.AddCoin(5);
Assert.AreEqual(originalCount + 1, testCoinBank.Coins[5]);
}
public void ComplexCase()
{
// Arrange
var bank = new CoinBank();
bank.AddCoin(CoinDenomination.TwentyPence);
bank.AddCoin(CoinDenomination.FiftyPence);
bank.AddCoin(CoinDenomination.TwentyPence);
bank.AddCoin(CoinDenomination.TenPence);
// Act
bank.Withdraw(0.80M);
// Assert
Assert.AreEqual(0.20M, bank.Balance);
}