public void ShouldInvokeLoanCalculatorAndReturnResult()
{
var input = new LoanParameters { Amount = 1, Years = 1 };
var mockResponse = new PaymentPlan(new List<PaymentMonth>());
_calculatorMock.Setup(it => it.CalculateLoan(input))
.Returns(mockResponse)
.Verifiable("Should call LoanCalculator with expected input");
var result = _controller.Calculate(input);
_calculatorMock.Verify();
Assert.AreSame(mockResponse, result);
}
public PaymentPlan Calculate(LoanParameters parameters)
{
//TODO: Extract validation and error handling to generic functionality
try {
Validate(parameters);
return _calculator.CalculateLoan(parameters);
}
catch (Exception ae)
{
var response = Request.CreateErrorResponse(HttpStatusCode.BadRequest, ae.Message);
throw new HttpResponseException(response);
}
}
private static void Validate(LoanParameters loanParameters)
{
if (loanParameters == null)
{
throw new ArgumentNullException(nameof(loanParameters));
}
if (loanParameters.Years <= 0)
{
throw new ZeroOrNegativeYearsException(nameof(loanParameters.Years), loanParameters.Years);
}
if (loanParameters.Amount < 0)
{
throw new NegativeAmountException(nameof(loanParameters.Amount), loanParameters.Amount);
}
}
public PaymentPlan CalculateLoan(LoanParameters loanParameters)
{
var loan = new HousingLoan(loanParameters);
var paymentScheme = new SeriesPaymentScheme();
var months = new List<PaymentMonth>();
for (int monthNumber = 1; monthNumber <= loan.NumberOfMonths; monthNumber++)
{
decimal monthlyPrincipal = paymentScheme.NextMonthlyPrincipal(loan);
var monthlyInterest = paymentScheme.NextMonthlyInterest(loan);
var monthlyTotal = monthlyPrincipal + monthlyInterest;
loan.Remaining -= monthlyPrincipal; //TODO: This doesn't smell right, should be immutable or just a local variable?
months.Add(new PaymentMonth(monthNumber, monthlyPrincipal, monthlyInterest, monthlyTotal, loan.Remaining));
}
var result = new PaymentPlan(months);
return result;
}
internal LoanStub(LoanParameters loanParameters) : base(loanParameters) { }
protected AbstractLoan(LoanParameters loanParameters)
{
Remaining = loanParameters.Amount;
LoanAmount = loanParameters.Amount;
NumberOfMonths = loanParameters.Years * 12;
}