old_contents: import unittest
  
  from sum_of_multiples import sum_of_multiples
  
  
  class SumOfMultiplesTest(unittest.TestCase):
      def test_sum_to_1(self):
          self.assertEqual(0, sum_of_multiples(1))
  
      def test_sum_to_3(self):
          self.assertEqual(3, sum_of_multiples(4))
  
      def test_sum_to_10(self):
          self.assertEqual(23, sum_of_multiples(10))
  
      def test_sum_to_1000(self):
          self.assertEqual(233168, sum_of_multiples(1000))
  
      def test_configurable_7_13_17_to_20(self):
          self.assertEqual(51, sum_of_multiples(20, [7, 13, 17]))
  
      def test_configurable_43_47_to_10000(self):
          self.assertEqual(2203160, sum_of_multiples(10000, [43, 47]))
  
      def test_configurable_0_to_10(self):
          self.assertEqual(0, sum_of_multiples(10, [0]))
  
      def test_configurable_0_1_to_10(self):
          self.assertEqual(45, sum_of_multiples(10, [0, 1]))
  
  
  if __name__ == '__main__':
      unittest.main()
  
new_contents: """
  You can make the following assumptions about the inputs to the
  'sum_of_multiples' function:
      * All input numbers are non-negative 'int's, i.e. natural numbers including
        zero.
      * If a list of factors is given, its elements are uniqe and sorted in
        ascending order.
      * If the 'factors' argument is missing, use the list [3, 5] instead.
  """
  
  import unittest
  
  from sum_of_multiples import sum_of_multiples
  
  
  class SumOfMultiplesTest(unittest.TestCase):
      def test_sum_to_1(self):
          self.assertEqual(0, sum_of_multiples(1))
  
      def test_sum_to_3(self):
          self.assertEqual(3, sum_of_multiples(4))
  
      def test_sum_to_10(self):
          self.assertEqual(23, sum_of_multiples(10))
  
      def test_sum_to_1000(self):
          self.assertEqual(233168, sum_of_multiples(1000))
  
      def test_configurable_7_13_17_to_20(self):
          self.assertEqual(51, sum_of_multiples(20, [7, 13, 17]))
  
      def test_configurable_43_47_to_10000(self):
          self.assertEqual(2203160, sum_of_multiples(10000, [43, 47]))
  
      def test_configurable_0_to_10(self):
          self.assertEqual(0, sum_of_multiples(10, [0]))
  
      def test_configurable_0_1_to_10(self):
          self.assertEqual(45, sum_of_multiples(10, [0, 1]))
  
  
  if __name__ == '__main__':
      unittest.main()
  
subject: Add short spec to test suite