new_contents: #!/usr/bin/env python
  #
  # This file is part of pySerial - Cross platform serial port support for Python
  # (C) 2016 Chris Liechti <cliechti@gmx.net>
  #
  # SPDX-License-Identifier:    BSD-3-Clause
  """\
  Test asyncio related functionality.
  """
  
  import unittest
  import serial
  
  # on which port should the tests be performed:
  PORT = '/dev/ttyUSB0'
  
  try:
      import asyncio
      import serial.aio
  except (ImportError, SyntaxError):
      # not compatible with python 2.x
      pass
  else:
  
      class Test_asyncio(unittest.TestCase):
          """Test asyncio related functionality"""
  
          def setUp(self):
              self.loop = asyncio.get_event_loop()
              # create a closed serial port
  
          def tearDown(self):
              self.loop.close()
  
          def test_asyncio(self):
              TEXT = b'hello world\n'
              received = []
              actions = []
  
              class Output(asyncio.Protocol):
                  def connection_made(self, transport):
                      self.transport = transport
                      actions.append('open')
                      transport.serial.rts = False
                      transport.write(TEXT)
  
                  def data_received(self, data):
                      #~ print('data received', repr(data))
                      received.append(data)
                      if b'\n' in data:
                          self.transport.close()
  
                  def connection_lost(self, exc):
                      actions.append('close')
                      asyncio.get_event_loop().stop()
  
                  def pause_writing(self):
                      actions.append('pause')
                      print(self.transport.get_write_buffer_size())
  
                  def resume_writing(self):
                      actions.append('resume')
                      print(self.transport.get_write_buffer_size())
  
              coro = serial.aio.create_serial_connection(self.loop, Output, PORT, baudrate=115200)
              self.loop.run_until_complete(coro)
              self.loop.run_forever()
              self.assertEqual(b''.join(received), TEXT)
              self.assertEqual(actions, ['open', 'close'])
  
  
  if __name__ == '__main__':
      import sys
      sys.stdout.write(__doc__)
      if len(sys.argv) > 1:
          PORT = sys.argv[1]
      sys.stdout.write("Testing port: %r\n" % PORT)
      sys.argv[1:] = ['-v']
      # When this module is executed from the command-line, it runs all its tests
      unittest.main()
  
subject: add test