// We only accept payments matching the Installment Amount. public void MakePayment(decimal amount, Guid installmentId) { Installment installment = Installments.First(i => i.Id == installmentId); if (amount != installment.Amount) { throw new ArgumentException(); } installment.SetPaid(Id, DateTime.Now); }
public Installment FirstInstallment() { return(Installments.First()); }