def METHOD_NAME(self, tctx: Context):
    nl = layer.NextLayer(tctx)
    playbook = tutils.Playbook(nl)
    assert (
        playbook
        >> events.DataReceived(tctx.client, b"foo")
        << layer.NextLayerHook(nl)
    )
    nl.layer = tutils.EchoLayer(tctx)
    handle = nl.handle_event
    playbook >> tutils.reply()
    playbook << commands.SendData(tctx.client, b"foo")
    assert playbook
    (sd,) = handle(events.DataReceived(tctx.client, b"bar"))
    assert isinstance(sd, commands.SendData)