old_contents: from unittest import TestCase
  
  import adder
  
  class TestAdd(TestCase):
      def test_int(self):
          r = adder.add(3,4)
          self.assertEqual(r, 7)
  
      def test_float(self):
          r = adder.add(3.5, 4.5)
          self.assertEqual(r, 8.0)
  
      def test_string(self):
          r = adder.add("toast", "jam")
          self.assertEqual(r, "toastjam")
  
      def test_mixed(self):
          with self.assertRaises(TypeError):
              adder.add("toast", 3)
  
new_contents: from unittest import TestCase
  
  import adder
  
  class TestAdd(TestCase):
      def test_int(self):
          r = adder.add(3,4)
          self.assertEqual(r, 7)
  
      def test_float(self):
          r = adder.add(3.5, 4.5)
          self.assertEqual(r, 8.0)
  
      def test_string(self):
          r = adder.add("toast", "jam")
          self.assertEqual(r, "toastjam")
  
      def test_mixed(self):
          with self.assertRaises(TypeError):
              adder.add("toast", 3)
  
      def test_break(self):
          self.assertEqual(False, True)
  
subject: Break the tests