old_contents: #!/usr/bin/env python
  
  import tests
  import os, sys
  
  if len(sys.argv) > 1 and sys.argv[1] == "update":
      if len(sys.argv) > 2:
          config = tests.get_config(os.path.dirname(sys.argv[2]))
          root, ext = os.path.splitext(sys.argv[2])
          if ext == config.get(tests.get_section(os.path.basename(root), config), 'input_ext'):
              tests.generate(root, config)
          else:
              print(file, 'does not have a valid file extension. Check config.')
      else:
          tests.generate_all()
  else:
      tests.run()
  
new_contents: #!/usr/bin/env python
  
  import tests
  import os, sys
  
  if len(sys.argv) > 1 and sys.argv[1] == "update":
      if len(sys.argv) > 2:
          config = tests.get_config(os.path.dirname(sys.argv[2]))
          root, ext = os.path.splitext(sys.argv[2])
          if ext == config.get(tests.get_section(os.path.basename(root), config), 'input_ext'):
              tests.generate(root, config)
          else:
              print(sys.argv[2], 'does not have a valid file extension. Check config.')
      else:
          tests.generate_all()
  else:
      tests.run()
  
subject: Fix NameError in run-tests.py