public void GetLoanPaymentOverwiew_ExpectedBehavior()
{
// Arrange
var loanPaymentCalculatorInternal = new LoanPaymentCalculatorInternal();
var loanParameters = new LoanParameters
{
LoanAmount = 500000,
DurationOfLoanInYears = 10,
};
var loanTerms = new LoanTerms
{
AnnualInterestRate = 0.05m,
PaymentsPerYear = 12,
AdminFeeRelative = 0.01m,
MaxAdminFee = 10000,
};
// Act
var result = loanPaymentCalculatorInternal.GetLoanPaymentOverwiew(
loanParameters,
loanTerms);
// Assert
Assert.Equal(500000, result.LoanAmount);
Assert.Equal(10, result.DurationOfLoanInYears);
Assert.Equal(5303.28m, result.MonthlyPayment);
Assert.Equal(136393.09m, result.AmountPaidAsInterest);
Assert.Equal(5000m, result.AdministrativeFee);
}
public OverviewDetails GetLoanPaymentOverwiew(LoanParameters loanParameters, LoanTerms loanTerms)
{
var loanAmount = loanParameters.LoanAmount;
var durationOfLoan = loanParameters.DurationOfLoanInYears;
var annualInterestRate = loanTerms.AnnualInterestRate;
var paymentsPerYear = loanTerms.PaymentsPerYear;
var adminFeeRelative = loanTerms.AdminFeeRelative;
var maxAdminFee = loanTerms.MaxAdminFee;
var amountOfPayments = durationOfLoan * paymentsPerYear;
var interestRatePerPayment = annualInterestRate / paymentsPerYear;
var monthlyPayment = this.GetMonthlyPayment((double)loanAmount, amountOfPayments, (double)interestRatePerPayment);
var totalAmmountPayed = monthlyPayment * amountOfPayments;
var amountPaidAsInterest = totalAmmountPayed - loanAmount;
var administrativeFee = this.GetAdministrativeFee(loanAmount, adminFeeRelative, maxAdminFee);
return(new OverviewDetails
{
LoanAmount = loanAmount,
DurationOfLoanInYears = durationOfLoan,
MonthlyPayment = Math.Round(monthlyPayment, 2),
AmountPaidAsInterest = Math.Round(amountPaidAsInterest, 2),
AdministrativeFee = Math.Round(administrativeFee, 2),
});
}
public PaymentOverview CalculatePaymentOverview(LoanParameters parameters, LoanTerms terms)
{
var totalNumberOfPayments = parameters.DurationInYears * terms.PaymentsInYear;
var administrativeFee = _loanCalculations.CalculateAdministrativeFee(
parameters.MoneyToLoan.Amount,
terms.AdministrativeFeeRate,
terms.AdministrativeFeeMaxCap
);
var singlePayment = _loanCalculations.CalculateSinglePayment(
parameters.MoneyToLoan.Amount,
terms.AnnualInterestRate,
terms.PaymentsInYear, totalNumberOfPayments
);
var totalPayment = _loanCalculations.CalculateTotalPayment(
singlePayment,
totalNumberOfPayments
);
var totalInterest = _loanCalculations.CalculateTotalInterest(
totalPayment,
parameters.MoneyToLoan.Amount
);
var aop = _loanCalculations.CalculateAop(
totalPayment,
administrativeFee,
parameters.MoneyToLoan.Amount,
parameters.DurationInYears
);
return(new PaymentOverview(
new Money(singlePayment),
new Money(totalPayment),
new Money(totalInterest),
new Money(administrativeFee),
new Percent(aop),
parameters,
terms
));
}
public void ShowLoanTerms(LoanTerms loanTerms)
{
Console.WriteLine($"\nLoan terms:");
Console.WriteLine(loanTerms.ToString());
}
