#[cfg(test)]
mod test {
    use bytes::Bytes;
    use std::collections::vec_deque::VecDeque;
    use std::convert::TryFrom;
    use zeromq::ZmqMessage;

    #[test]
    fn test_split_off() {
        let mut frames = VecDeque::with_capacity(5);
        frames.push_back(Bytes::from("id1"));
        frames.push_back(Bytes::from("id2"));
        frames.push_back(Bytes::from(""));
        frames.push_back(Bytes::from("data1"));
        frames.push_back(Bytes::from("data2"));
        let mut m = ZmqMessage::try_from(frames).unwrap();
        let data = m.split_off(3);
        assert_eq!(m.len(), 3);
        assert_eq!(m.get(0), Some(&Bytes::from("id1")));
        assert_eq!(m.get(1), Some(&Bytes::from("id2")));
        assert_eq!(m.get(2), Some(&Bytes::from("")));
        assert_eq!(data.len(), 2);
        assert_eq!(data.get(0), Some(&Bytes::from("data1")));
        assert_eq!(data.get(1), Some(&Bytes::from("data2")));
    }

    #[test]
    fn test_prepend() {
        let mut frames = VecDeque::with_capacity(2);
        frames.push_back(Bytes::from("data1"));
        frames.push_back(Bytes::from("data2"));
        let mut m = ZmqMessage::try_from(frames).unwrap();

        let mut envelope_frames = VecDeque::with_capacity(3);
        envelope_frames.push_back(Bytes::from("id1"));
        envelope_frames.push_back(Bytes::from("id2"));
        envelope_frames.push_back(Bytes::from(""));
        let envelope = ZmqMessage::try_from(envelope_frames).unwrap();

        m.prepend(&envelope);
        assert_eq!(m.len(), 5);
        assert_eq!(m.get(0), Some(&Bytes::from("id1")));
        assert_eq!(m.get(1), Some(&Bytes::from("id2")));
        assert_eq!(m.get(2), Some(&Bytes::from("")));
        assert_eq!(m.get(3), Some(&Bytes::from("data1")));
        assert_eq!(m.get(4), Some(&Bytes::from("data2")));
    }
}