Hi,
I have written a code for Roman Numeral basic mathematical operation in C++. How to do unit testing for it/ How to write unit testing program for it?

Here is the code:

#include <iostream>
#include <string>

using namespace std;

//Function to convert decimal number to roman
string decimal_to_Roman(int number)
{
    string roman = "";
    while (number > 0)
    {
        if (number >= 1000)
        {
            roman += "M";
            number -= 1000;
        }
        else if (number >= 500)
        {
            roman += "D";
            number -= 500;
        }
        else if (number >= 100)
        {
            roman += "C";
            number -= 100;
        }
        else if (number >= 50)
        {
            roman += "L";
            number -= 50;
        }
        else if (number >= 10)
        {
            roman += "X";
            number -= 10;
        }
        else if (number >= 5)
        {
            roman += "V";
            number -= 5;
        }
        else
        {
            roman += "I";
            number -= 1;
        }
    }
    return roman;
}

//Function to convert roman number to decimal
int roman_to_decimal(string roman)
{
    int number = 0;
    for (int i = 0; i<roman.length(); i++)
    {
        switch (roman[i])
        {
        case 'M':
            number += 1000;
            break;
        case 'D':
            number += 500;
            break;
        case 'C':
            number += 100;
            break;
        case 'L':
            number += 50;
            break;
        case 'X':
            number += 10;
            break;
        case 'V':
            number += 5;
            break;
        case 'I':
            number += 1;
            break;
        default:
            cout << "Data error\n";
        }
    }
    return number;
}

//Function to perform mathematical operations(+,-,*,/)
int calculator(int n1, int n2, char opr)
{
    switch (opr)
    {
    case '+':
        return n1 + n2;
        break;
    case '-':
        return n1 - n2;
        break;
    case '*':
        return n1*n2;
        break;
    case '/':
        if (n2 != 0)
        {
            return n1 / n2;
        }
        else
            break;
    }
    return 0;
}

//Function to print result
void result(string r1, string r2, char opr, string r)
{
    cout << r1 << endl;
    cout << opr << endl;
    cout << r2 << endl; 
    cout << r << endl;
}

int main()
{
    string r1, r2, r;
    char opr;
    int n1, n2, n;
        cin >> r1;
            n1 = roman_to_decimal(r1);
        cin >> opr;
        cin >> r2;
        n2 = roman_to_decimal(r2);
    n = calculator(n1, n2, opr);
    r = decimal_to_Roman(n);
    result(r1, r2, opr, r);
}

If you don't have a unit testing framework at hand, you could use some simple asserts for now, I guess. It might depend on what IDE you use too, because, for example, I have been using Visual Studio's unit testing 'framework' for some time now and it's pretty elegant. As I said, without knowing exactly what IDE, compiler, OS you're using, can't recommend much more than writing some asserts.

System Config- windows 10 32 bit
I coded it on online ide

Today i installed Visual Studio to compile it offline, but there is some configuration problem and not able to run the program

commented: I don't think so!??? +0

Ditto what Coller said. Or even forget the asserts for now. Just run the program for some obvious tests. IV seems to return 6 instead of 4.

When it passes all the obvious stuff you can throw at it, then worry about Unit Testing IMO.

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