message: capture_output is not available on old versions of python 3
diff: @@ -24,9 +24,9 @@ def test(cmd, out=None, err=None, extra_commands=None, input_file=None):
  command += extra_commands
  if input_file:
  command += [cmd]
  - res = subprocess.run(command, capture_output=True, input=open(input_file, 'rb').read())
  + res = subprocess.run(command, input=open(input_file, 'rb').read(), stdout=subprocess.PIPE, stderr=subprocess.PIPE)
  else:
  - res = subprocess.run(command, capture_output=True, input=bytearray(cmd, 'utf8'))
  + res = subprocess.run(command, input=bytearray(cmd, 'utf8')), stdout=subprocess.PIPE, stderr=subprocess.PIPE
  stdout = res.stdout.decode('utf8').strip()
  stderr = res.stderr.decode('utf8').strip()
  