old_contents: #!/usr/bin/env python3
  
  import os
  import sys
  import unittest
  
  sys.path.insert(0, os.path.join(os.path.dirname(__file__), '..'))
  
  load = unittest.defaultTestLoader.loadTestsFromModule
  
  suites = []
  dirname = os.path.dirname(__file__)
  sys.path.append(dirname)
  filenames = os.listdir(dirname)
  for filename in filenames:
      if filename.startswith('test_') and filename.endswith('.py'):
          name = filename[:-3]
          plugin = __import__(name)
          suites.append(load(plugin))
  
  if __name__ == '__main__':
      suite = unittest.TestSuite(suites)
      runner = unittest.TextTestRunner(verbosity=2)
      result = runner.run(suite)
  
new_contents: #!/usr/bin/env python3
  
  import os
  import sys
  import unittest
  
  sys.path.insert(0, os.path.join(os.path.dirname(__file__), '..'))
  
  load = unittest.defaultTestLoader.loadTestsFromModule
  
  suites = []
  dirname = os.path.dirname(__file__)
  sys.path.append(dirname)
  filenames = os.listdir(dirname)
  for filename in filenames:
      if filename.startswith('test_') and filename.endswith('.py'):
          name = filename[:-3]
          plugin = __import__(name)
          suites.append(load(plugin))
  
  if __name__ == '__main__':
      suite = unittest.TestSuite(suites)
      runner = unittest.TextTestRunner(verbosity=2)
      result = runner.run(suite)
      if result.wasSuccessful():
          sys.exit(0)
      else:
          sys.exit(1)
  
subject: Fix return value of tests.