mod to_hex_with_len {    #[test]    fn display_entire_range_sha1() {        let id_hex = "0123456789abcdef123456789abcdef123456789";        let id = git_hash::ObjectId::from_hex(id_hex.as_bytes()).expect("valid input");        for len in 0..=40 {            assert_eq!(id.to_hex_with_len(len).to_string(), id_hex[..len]);        }        assert_eq!(            id.to_hex_with_len(120).to_string(),            id_hex,            "values that are too long are truncated"        );    }}