old_contents: import unittest
  
  
  class IronicPythonHeartbeaterTestCase(unittest.TestCase):
      def test_dummy(self):
          self.assertTrue(True)
  
new_contents: import unittest
  
  import mock
  
  from ironic_python_heartbeater import ironic_python_heartbeater as iph
  
  
  class IronicPythonHeartbeaterTestCase(unittest.TestCase):
  
      def test__parse_kernel_cmdline(self):
          fake_kernel_opts = "spam=ham foo=bar"
          expected_opts = {'spam': 'ham', 'foo': 'bar'}
          with mock.patch.object(iph, 'open',
                                 new=mock.mock_open(read_data=fake_kernel_opts)):
              self.assertEqual(expected_opts, iph._parse_kernel_cmdline())
  
subject: Add first unit test