number_to_roman.py

import unittest
from math import *

class KataTests(unittest.TestCase):

    def test_on_one(self):
        self.assertEqual(number_to_roman(1), "I")

    def test_on_two(self):
        self.assertEqual(number_to_roman(2), "II")

    def test_on_three(self):
        self.assertEqual(number_to_roman(3), "III")

    def test_on_four(self):
        self.assertEqual(number_to_roman(4), "IV")

    def test_on_five(self):
        self.assertEqual(number_to_roman(5), "V")

    def test_on_six(self):
        self.assertEqual(number_to_roman(6), "VI")

    def test_on_seven(self):
        self.assertEqual(number_to_roman(7), "VII")

    def test_on_nine(self):
        self.assertEqual(number_to_roman(9), "IX")

    def test_on_ten(self):
        self.assertEqual(number_to_roman(10), "X")

    def test_on_twenty(self):
        self.assertEqual(number_to_roman(20), "XX")

    def test_on_fourty(self):
        self.assertEqual(number_to_roman(40), "XL")

    def test_on_fifty(self):
        self.assertEqual(number_to_roman(50), "L")

    def test_on_sixty(self):
        self.assertEqual(number_to_roman(60), "LX")

    def test_on_eighty(self):
        self.assertEqual(number_to_roman(80), "LXXX")

    def test_on_ninety(self):
        self.assertEqual(number_to_roman(90), "XC")

    def test_on_one_hundred(self):
        self.assertEqual(number_to_roman(100), "C")

    def test_on_two_hundred(self):
        self.assertEqual(number_to_roman(200), "CC")

    def test_on_four_hundred(self):
        self.assertEqual(number_to_roman(400), "CD") 

    def test_on_five_hundred(self):
        self.assertEqual(number_to_roman(500), "D")

    def test_on_six_hundred(self):
        self.assertEqual(number_to_roman(600), "DC")

    def test_on_nine_hundred(self):
        self.assertEqual(number_to_roman(900), "CM")

    def test_on_one_thousand(self):
        self.assertEqual(number_to_roman(1000), "M")

    def test_on_two_thousand(self):
        self.assertEqual(number_to_roman(2000), "MM")

    def test_on_twenty_one(self):
        self.assertEqual(number_to_roman(22), "XXII")

def number_to_roman(n):
    result = ""
    i = len(str(n))
    while n >= 1 :
        result += digit_to_roman(n)
        n -= pow(10,i)
        i -= 1
    return result

def digit_to_roman(n):
    if n >= 1000 :
        return "M" * int(n/1000)
    if n == 900 :
        return "CM"
    if n >= 500 :
        return "D" + "C" * int((n-500)/100)
    if n == 400 :
        return "CD"
    if n >= 100 :
        return "C" * int(n/100)
    if n == 90 :
        return "XC"
    if n >= 50 :
        return "L" + "X" * int((n-50)/10)
    if n == 40 :
        return "XL"
    if n >= 10 :
        return "X" * int(n/10)
    if n == 9 :
        return "IX"
    if n >= 5 :
        return "V" + "I" * int(n-5)
    if n == 4 :
        return "IV"
    return "I" * n

def main():
    unittest.main()

if __name__ == '__main__':
    main()