def METHOD_NAME(self):
    """
    Adding a filesystem file writer to a reactor will make sure it is
    polled.
    """
    reactor = self.buildReactor()
    class DisconnectProtocol(Protocol):
        def connectionLost(self, reason):
            reactor.stop()
    path = self.mktemp()
    with open(path, "wb") as f:
        # Write bytes to a transport, hopefully have them written to a
        # file:
        protocol = DisconnectProtocol()
        StandardIO(
            protocol,
            stdout=f.fileno(),
            stdin=self.extraFile.fileno(),
            reactor=reactor,
        )
        protocol.transport.write(b"hello")
        protocol.transport.write(b", world")
        protocol.transport.loseConnection()
        self.runReactor(reactor)
    with open(path, "rb") as f:
        self.assertEqual(f.read(), b"hello, world")