You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: picture_loss_indication_test.rs
    path of file: ./repos/webrtc/rtcp/src/payload_feedbacks/picture_loss_indication
    
    the code of the file until where you have to start completion: use bytes::Bytes;

use super::*;

#[test]
fn test_picture_loss_indication_unmarshal() {
    let tests = vec![
        (
            "valid",
            Bytes::from_static(&[
                0x81, 0xce, 0x00, 0x02, // v=2, p=0, FMT=1, PSFB, len=1
                0x00, 0x00, 0x00, 0x00, // ssrc=0x0
                0x4b, 0xc4, 0xfc, 0xb4, // ssrc=0x4bc4fcb4
            ]),
            PictureLossIndication {
                sender_ssrc: 0x0,
                media_ssrc: 0x4bc4
    
fn test_picture_loss_indication_roundtrip() {
    let tests: Vec<(&str, PictureLossIndication, Option<Error>)> = vec![
        (
            "valid",
            PictureLossIndication {
                sender_ssrc: 1,
                media_ssrc: 2,
            },
            None,
        ),
        (
            "also valid",
            PictureLossIndication {
                sender_ssrc: 5000,
                media_ssrc: 6000,
            },
            None,
        ),
    ];

    for (name, want, want_error) in tests {
        let got = want.marshal();

        assert_eq!(
            got.is_ok(),
            want_error.is_none(),
            "Marshal {name}: err = {got:?}, want {want_error:?}"
        );

        if let Some(err) = want_error {
            let got_err = got.err().unwrap();
            assert_eq!(
                err, got_err,
                "Unmarshal {name} rr: err = {got_err:?}, want {err:?}",
            );
        } else {
            let mut data = got.ok().unwrap();
            let actual = PictureLossIndication::unmarshal(&mut data)
                .unwrap_or_else(|_| panic!("Unmarshal {name}"));

            assert_eq!(
                actual, want,
                "{name} round trip: got {actual:?}, want {want:?}"
            )
        }
    }
}