new_contents: import os
  import unittest
  
  import spellnum
  
  answers_upto_100 = {
      1: 'one', 2: 'two', 3: 'three', 4: 'four', 5: 'five', 6: 'six', 7: 'seven', 8: 'eight',
      9: 'nine', 10: 'ten', 11: 'eleven', 12: 'twelve', 13: 'thirteen', 14: 'fourteen',
      15: 'fifteen', 16: 'sixteen', 17: 'seventeen', 18: 'eighteen', 19: 'nineteen', 20: 'twenty',
      21: 'twenty-one', 22: 'twenty-two', 23: 'twenty-three', 24: 'twenty-four', 25: 'twenty-five',
      26: 'twenty-six', 27: 'twenty-seven', 28: 'twenty-eight', 29: 'twenty-nine', 30: 'thirty',
      31: 'thirty-one', 32: 'thirty-two', 33: 'thirty-three', 34: 'thirty-four', 35: 'thirty-five',
      36: 'thirty-six', 37: 'thirty-seven', 38: 'thirty-eight', 39: 'thirty-nine', 40: 'forty',
      41: 'forty-one', 42: 'forty-two', 43: 'forty-three', 44: 'forty-four', 45: 'forty-five',
      46: 'forty-six', 47: 'forty-seven', 48: 'forty-eight', 49: 'forty-nine', 50: 'fifty',
      51: 'fifty-one', 52: 'fifty-two', 53: 'fifty-three', 54: 'fifty-four', 55: 'fifty-five',
      56: 'fifty-six', 57: 'fifty-seven', 58: 'fifty-eight', 59: 'fifty-nine', 60: 'sixty',
      61: 'sixty-one', 62: 'sixty-two', 63: 'sixty-three', 64: 'sixty-four', 65: 'sixty-five',
      66: 'sixty-six', 67: 'sixty-seven', 68: 'sixty-eight', 69: 'sixty-nine', 70: 'seventy',
      71: 'seventy-one', 72: 'seventy-two', 73: 'seventy-three', 74: 'seventy-four', 75: 'seventy-five',
      76: 'seventy-six', 77: 'seventy-seven', 78: 'seventy-eight', 79: 'seventy-nine', 80: 'eighty',
      81: 'eighty-one', 82: 'eighty-two', 83: 'eighty-three', 84: 'eighty-four', 85: 'eighty-five',
      86: 'eighty-six', 87: 'eighty-seven', 88: 'eighty-eight', 89: 'eighty-nine', 90: 'ninety',
      91: 'ninety-one', 92: 'ninety-two', 93: 'ninety-three', 94: 'ninety-four', 95: 'ninety-five',
      96: 'ninety-six', 97: 'ninety-seven', 98: 'ninety-eight', 99: 'ninety-nine'
  }
  
  answers_upto_1000 = {
      100: 'one hundred',
      101: 'one hundred one',
      102: 'one hundred two',
      109: 'one hundred nine',
      110: 'one hundred ten',
      120: 'one hundred twenty',
      121: 'one hundred twenty-one',
      198: 'one hundred ninety-eight',
      199: 'one hundred ninety-nine',
      200: 'two hundred',
      203: 'two hundred three',
      204: 'two hundred four',
      211: 'two hundred eleven',
      212: 'two hundred twelve',
      232: 'two hundred thirty-two',
      299: 'two hundred ninety-nine',
      300: 'three hundred',
      400: 'four hundred',
      500: 'five hundred',
      600: 'six hundred',
      700: 'seven hundred',
      800: 'eight hundred',
      900: 'nine hundred',
      999: 'nine hundred ninety-nine'
  }
  
  answers_upto_infinity = {
      1000: 'one thousand',
      2000: 'two thousand',
      3000: 'three thousand',
      10000: 'ten thousand',
      13000: 'thirteen thousand',
      90000: 'ninety thousand',
      30000: 'thirty thousand',
  
      1346: 'one thousand three hundred forty-six',
      11482: 'eleven thousand four hundred eighty-two',
      13851: 'thirteen thousand eight hundred fifty-one',
      23016: 'twenty-three thousand sixteen',
      100000: 'one hundred thousand',
      750000: 'seven hundred fifty thousand',
      934756: 'nine hundred thirty-four thousand seven hundred fifty-six',
  
      1000000: 'one million',
      143000000: 'one hundred forty-three million',
      143007000: 'one hundred forty-three million seven thousand',
      2408701047: 'two billion four hundred eight million seven hundred one thousand forty-seven',
      10680040002031: 'ten trillion six hundred eighty billion forty million two thousand thirty-one'
  }
  
  
  class Test(unittest.TestCase):
      def setUp(self):
          self.speller = spellnum.Speller()
  ###
      def test_upto_100(self):
          self._run_test(answers_upto_100)
  
      def test_upto_1000(self):
          self._run_test(answers_upto_1000)
  
      def test_upto_infinity(self):
          self._run_test(answers_upto_infinity)
  ###
      def _run_test(self, answers):
          for num, spelling in answers.items():
              self.assertEqual(spelling, self.speller.spell(num))
  
  
  if __name__ == '__main__':
      unittest.main()
  
subject: Add unit tests