public ILoanCalculationModel CalculateLoanStatistics(ILoanInfoModel loanInfoModel)
{
var result = new LoanCalculationModel();
//Validate icoming data
if (loanInfoModel == null)
{
throw new LoanInfoModelNotFoundException();
}
if (loanInfoModel.Amount <= 0)
{
throw new InvalidAmountException();
}
if (loanInfoModel.Interest <= 0 || loanInfoModel.Interest > 100)
{
throw new InvalidInterestException();
}
if (loanInfoModel.Downpayment < 0 || loanInfoModel.Downpayment >= loanInfoModel.Amount)
{
throw new InvalidDownPaymentException();
}
if (loanInfoModel.Term <= 0)
{
throw new InvalidTermException();
}
//Calculating Loan info statistics(validation inside)
result.MonthlyPayment = ((loanInfoModel.Amount - loanInfoModel.Downpayment) *
((double)loanInfoModel.Interest / 100) / 12) /
(1 - (1 / (Math.Pow((1 + ((double)loanInfoModel.Interest / 100) / 12), loanInfoModel.Term * 12))));
result.TotalPayment = (loanInfoModel.Term * 12 * result.MonthlyPayment);
result.TotalInterest = result.TotalPayment - (loanInfoModel.Amount - loanInfoModel.Downpayment);
return(result);
}
public void CalculateLoanStatisticsMethodThrowExceptionIfNotparamIsNull(ILoanInfoModel term)
{
var manager = new LoanManager();
Assert.Throws <LoanInfoModelNotFoundException>(() => manager.CalculateLoanStatistics(term));
}
