old_contents: import unittest
  
  class myTestSuite(unittest.TestCase):
      def setup(self):
          pass
  
      def tearDown(self):
          pass
  
      def number2roman(self, number):
  	if(number == 3):
  	    return "III"
  	if(number == 2):
  	    return "II"
          return "I" 
  
      def test_1_return_I(self):
          self.assertEqual(self.number2roman(1), "I")
  
      def test_2_return_II(self):
          self.assertEqual(self.number2roman(2), "II")
  
      def test_3_return_III(self):
          self.assertEqual(self.number2roman(3), "III")
  if __name__ == "__main__":
      unittest.main()
  
new_contents: import unittest
  
  class myTestSuite(unittest.TestCase):
      def setup(self):
          pass
  
      def tearDown(self):
          pass
  
      def number2roman(self, number):
  	preset_roman = ["","I","II","III"]
  	return preset_roman[number]
  
  
      def test_0_return_empty(self):
          self.assertEqual(self.number2roman(0), "")
  
      def test_1_return_I(self):
          self.assertEqual(self.number2roman(1), "I")
  
      def test_2_return_II(self):
          self.assertEqual(self.number2roman(2), "II")
  
      def test_3_return_III(self):
          self.assertEqual(self.number2roman(3), "III")
  if __name__ == "__main__":
      unittest.main()
  
subject: refactor code and add 0 to empty