async def METHOD_NAME(self, *, event):
    callback = Mock(name="callback")
    event._send = AsyncMock(name="event._send")
    event.headers = {"k": "v"}
    await event.send(
        channel="chan",
        partition=3,
        timestamp=None,
        schema=None,
        key_serializer="kser",
        value_serializer="vser",
        callback=callback,
    )
    event._send.assert_called_once_with(
        "chan",
        event.key,
        event.value,
        3,
        None,
        event.headers,
        None,
        "kser",
        "vser",
        callback,
        force=False,
    )