def METHOD_NAME(self):
    cline = EchoApp(text="Hello World")
    tmp = "echo_stdout_stderr.tmp"
    if os.path.isfile(tmp):
        os.remove(tmp)
    stdout, stderr = cline(stdout=tmp, stderr=tmp)
    self.assertIsNone(stderr)
    self.assertIsNone(stdout)
    self.assertTrue(os.path.isfile(tmp))
    with open(tmp) as handle:
        contents = handle.read()
    self.assertEqual(contents, "Hello World\n")  # stdout + stderr
    os.remove(tmp)