def METHOD_NAME(self):
    # Re-usable protocol and reactor
    self.protocol = Protocol()
    self.reactor = DoNothing()
    self.directory = tempfile.mkdtemp()
    self.path = os.path.join(self.directory, "fake_serial")
    data = b"1234"
    with open(self.path, "wb") as f:
        f.write(data)