async def METHOD_NAME(self):
    """Test connection_state_changed after register."""
    xknx = XKNX()
    async_connection_state_changed_cb = AsyncMock()
    xknx.connection_manager.register_connection_state_changed_cb(
        async_connection_state_changed_cb
    )
    await xknx.connection_manager.connection_state_changed(
        XknxConnectionState.CONNECTED, XknxConnectionType.ROUTING_SECURE
    )
    async_connection_state_changed_cb.assert_called_once_with(
        XknxConnectionState.CONNECTED
    )