public void GetPresentValue_Should_Throw_ArgumentOutOfRangeException_When_Interest_Rate_Less_Than_Zero()
{
//Arrange
double repayment = 10000;
double interestRate = -4.8;
int loanTerm = 3;
FinanceLib sut = new FinanceLib();
//Assert
Assert.Throws <ArgumentOutOfRangeException>(() => { sut.GetPresentValue(repayment, interestRate, loanTerm); });
}
public void Should_Return_Present_Value_Of_Loan()
{
//Arrange
double repayment = 250;
double interestRate = 4.8;
int loanTerm = 3;
double expectedResult = 8366.47;
FinanceLib sut = new FinanceLib();
//Act
double actualResult = sut.GetPresentValue(repayment, interestRate, loanTerm);
//Assert
Assert.Equal(expectedResult, Math.Round(actualResult, 2));
}
static void Main(string[] args)
{
string choice = "";
do
{
//Get menu choice
ShowMenu();
choice = Console.ReadLine();
//calculate monthly repayment
if (choice == "1")
{
double loanAmount;
do
{
Console.WriteLine("Enter the loan amount in dollars (e.g. 10000):");
} while (!Double.TryParse(Console.ReadLine(), out loanAmount) || loanAmount <= 0);
double interestRate;
do
{
Console.WriteLine("Enter interest rate as a percentage (e.g. 5.2):");
} while (!Double.TryParse(Console.ReadLine(), out interestRate) || interestRate <= 0);
int loanTermInYears;
do
{
Console.WriteLine("Enter the term of the loan in years (e.g. 5):");
} while (!Int32.TryParse(Console.ReadLine(), out loanTermInYears) || loanTermInYears <= 0);
//create new calculator object to call repayment method
//Note: This could also be made into a static class if little domain logic is required
FinanceLib calculator = new FinanceLib();
try
{
double monthlyRepayment = calculator.GetRepayment(loanAmount, interestRate, loanTermInYears);
Console.WriteLine($"Monthly Repayments: ${Math.Round(monthlyRepayment,2)}");
Console.WriteLine();
//Append details of loan calculation to loans.txt file
//This file is in the bin folder so will be removed if a clean of the project is performed. For a real system this data
//would be persisted in a proper data store
using (StreamWriter writer = new StreamWriter("loans.txt", true))
{
writer.WriteLine(calculator);
}
}
//probably never hit as UI does some valdiation
catch (ArgumentOutOfRangeException ex)
{
Console.WriteLine(ex.Message);
Console.WriteLine();
}
}
//Present Value calculation
else if (choice == "2")
{
double repayment;
//get input and validate
do
{
Console.WriteLine("Enter the monthly repayment amount in dollars (e.g. 250):");
} while (!Double.TryParse(Console.ReadLine(), out repayment) || repayment <= 0);
double interestRate;
do
{
Console.WriteLine("Enter interest rate as a percentage (e.g. 5.2):");
} while (!Double.TryParse(Console.ReadLine(), out interestRate) || interestRate <= 0);
int loanTermInYears;
do
{
Console.WriteLine("Enter the term of the loan in years (e.g. 5):");
} while (!Int32.TryParse(Console.ReadLine(), out loanTermInYears) || loanTermInYears <= 0);
//create new calculator object to call repayment method
//Note: This could also be made into a static class if little domain logic is required
FinanceLib calculator = new FinanceLib();
try
{
double presentValue = calculator.GetPresentValue(repayment, interestRate, loanTermInYears);
Console.WriteLine($"Present Value of the loan: ${Math.Round(presentValue, 2)}");
Console.WriteLine();
//Append details of loan calculation to loans.txt file
//This file is in the bin folder so will be removed if a clean of the project is performed. For a real system this data
//would be persisted in a proper data store
using (StreamWriter writer = new StreamWriter("loans.txt", true))
{
writer.WriteLine(calculator);
}
}
//probably never hit as UI does some valdiation
catch (ArgumentOutOfRangeException ex)
{
Console.WriteLine(ex.Message);
Console.WriteLine();
}
}
//display calculations saved to file
else if (choice == "3")
{
try
{ // Open the text file using a stream reader.
using (StreamReader sr = new StreamReader("loans.txt"))
{
// Read the stream to a string, and write the string to the console.
String line = sr.ReadToEnd();
Console.WriteLine(line);
}
}
catch (Exception e)
{
Console.WriteLine("The file could not be read:");
Console.WriteLine(e.Message);
}
}
}while (choice != "4");
Console.WriteLine("Exiting program...");
}
