public IActionResult Payments([BindRequired] CreditParams credit)
{
//Check model
if (!ModelState.IsValid)
{
var res = Json(new { Error = BadRequest(ModelState).Value });
res.StatusCode = 400;
return(res);
}
//Check downpayment
else if (credit.Downpayment >= credit.Amount)
{
var res = Json(new { Error = "Downpayment sould be less than credit amount" });
res.StatusCode = 400;
return(res);
}
//Calculate payments
double withoutDownpayment = credit.Amount - credit.Downpayment;
double percentsPow = Math.Pow(1d + credit.Interest, credit.Term);
double yearPayment = withoutDownpayment * credit.Interest * (1d + 1d / (percentsPow - 1d));
var payments = new PaymentsParams();
payments.MonthlyPayment = yearPayment / 12d;
payments.TotalPayment = yearPayment * credit.Term;
payments.TotalInterest = payments.TotalPayment - credit.Amount;
return(Json(payments));
}
public void PaymentsInvalidModel()
{
var credit = new CreditParams();
var controller = new CreditController();
controller.ModelState.AddModelError("some", "error");
var actionResult = controller.Payments(credit) as JsonResult;
var errorField = actionResult.Value.GetType().GetProperty("Error");
Assert.NotNull(errorField);
}
public void PaymentsIncorrectDownpayment()
{
var credit = new CreditParams()
{
Amount = 100000,
Interest = 0.055,
Downpayment = 110000,
Term = 30
};
var controller = new CreditController();
var actionResult = controller.Payments(credit) as JsonResult;
var errorField = actionResult.Value.GetType().GetProperty("Error");
Assert.NotNull(errorField);
}
public void PaymentsWithoutDownpayment()
{
var credit = new CreditParams()
{
Amount = 100000,
Interest = 0.055,
Downpayment = 0,
Term = 30
};
var controller = new CreditController();
var actionResult = controller.Payments(credit) as JsonResult;
var payments = actionResult.Value as PaymentsParams;
Assert.Equal("573.38", payments.MonthlyPayment.ToString("F2", CultureInfo.InvariantCulture));
Assert.Equal("106416.17", payments.TotalInterest.ToString("F2", CultureInfo.InvariantCulture));
Assert.Equal("206416.17", payments.TotalPayment.ToString("F2", CultureInfo.InvariantCulture));
}
public void PaymentsCorrect()
{
var credit = new CreditParams()
{
Amount = 100000,
Interest = 0.055,
Downpayment = 20000,
Term = 30
};
var controller = new CreditController();
var actionResult = controller.Payments(credit) as JsonResult;
var payments = actionResult.Value as PaymentsParams;
Assert.Equal("458.70", payments.MonthlyPayment.ToString("F2", CultureInfo.InvariantCulture));
Assert.Equal("65132.94", payments.TotalInterest.ToString("F2", CultureInfo.InvariantCulture));
Assert.Equal("165132.94", payments.TotalPayment.ToString("F2", CultureInfo.InvariantCulture));
}
