old_contents: #!/usr/bin/env python
  
  import unittest
  import rospy
  import rostest
  
  from scripts.double import double
  
  class TestCase(unittest.TestCase):
  
      def test_four(self):
          ret = double(2)
          self.assertEqual(8, ret)
  
      def test_two(self):
          ret = double(2)
          self.assertEqual(4, ret)
  
      def test_good_math(self):
          ret = double(3)
          self.assertEqual(6, ret)
  
  if __name__ == '__main__':
      rostest.rosrun('package_name', 'test_name', TestCase)
  
new_contents: #!/usr/bin/env python
  
  import unittest
  import rospy
  import rostest
  
  from scripts.double import double
  
  class TestCase(unittest.TestCase):
  
      def test_four(self):
          ret = double(4)
          self.assertEqual(8, ret)
  
      def test_two(self):
          ret = double(2)
          self.assertEqual(4, ret)
  
      def test_good_math(self):
          ret = double(3)
          self.assertEqual(6, ret)
  
  if __name__ == '__main__':
      rostest.rosrun('package_name', 'test_name', TestCase)
  
subject: Fix the python test.