public void Deposit_ValidCoins_IncreasesBalance()
 {
     var o = new Operation(MockRepository.GenerateStub<IWallet>(), MockRepository.GenerateStub<IWallet>(), MockRepository.GenerateStub<ICook>());
     o.Balance = 10;
     o.Deposit(3, 4);
     Assert.AreEqual(22, o.Balance);
 }