mod line {    mod write_to {        use bstr::ByteVec;        use git_ref::file::log;         #[test]        fn newlines_in_message_of_the_input_fails_and_we_trust_signature_writing_validation() -> crate::Result {            let line = "0000000000000000000000000000000000000000 134385f6d781b7e97062102c6a483440bfda2a03 committer <committer@example.com> 946771200 +0000	commit (initial): c1";            let mut line = log::Line::from_bytes(line.as_bytes())?.to_mutable();            line.message.push_str("and here come\nthe newline");            let err = line                .write_to(&mut Vec::new())                .expect_err("newlines in messages are caught");            assert!(err.to_string().contains("newline"));            Ok(())        }         #[test]        fn round_trips() -> crate::Result {            let lines = &["0000000000000000000000000000000000000000 134385f6d781b7e97062102c6a483440bfda2a03 committer <committer@example.com> 946771200 +0000	commit (initial): c1\n",                          "0000000000000000000000000000000000000000 134385f6d781b7e97062102c6a483440bfda2a03 committer <committer@example.com> 946771200 +0000	\n"];            for line in lines {                let line = log::Line::from_bytes(line.as_bytes())?;                let mut buf = Vec::new();                line.to_mutable().write_to(&mut buf)?;                let same_line = log::Line::from_bytes(&buf)?;                assert_eq!(line, same_line);            }            Ok(())        }    }} mod iter {    use std::path::PathBuf;     fn reflog_dir() -> crate::Result<PathBuf> {        Ok(            git_testtools::scripted_fixture_repo_read_only("make_repo_for_reflog.sh")?                .join(".git")                .join("logs"),        )    }    fn reflog(name: &str) -> crate::Result<Vec<u8>> {        Ok(std::fs::read(reflog_dir()?.join(name))?)    }     mod backward {        mod with_buffer_too_small_for_single_line {            #[test]            fn single_line() -> crate::Result {                let mut buf = [0u8; 128];                let two_lines: Vec<u8> = b"0000000000000000000000000000000000000000 134385f6d781b7e97062102c6a483440bfda2a03 committer <committer@example.com> 946771200 +0000	commit (initial): c1".to_vec();                let two_lines_trailing_nl = {                    let mut l = two_lines.clone();                    l.push(b'\n');                    l                };                for line in &[two_lines, two_lines_trailing_nl] {                    let read = std::io::Cursor::new(line);                    let mut iter = git_ref::file::log::iter::reverse(read, &mut buf)?;                    assert_eq!(                        iter.next()                            .expect("an error")                            .expect_err("buffer too small")                            .get_ref()                            .expect("inner error")                            .to_string(),                        "buffer too small for line size"                    );                    assert!(iter.next().is_none(), "iterator depleted");                }                Ok(())            }        }         mod with_buffer_big_enough_for_largest_line {            use git_ref::file::log::mutable::Line;            use git_testtools::hex_to_id;             #[test]            fn single_line() -> crate::Result {                let mut buf = [0u8; 1024];                let two_lines: Vec<u8> = b"0000000000000000000000000000000000000000 134385f6d781b7e97062102c6a483440bfda2a03 committer <committer@example.com> 946771200 +0000	commit (initial): c1".to_vec();                let two_lines_trailing_nl = {                    let mut l = two_lines.clone();                    l.push(b'\n');                    l                };                for line in &[two_lines, two_lines_trailing_nl] {                    let read = std::io::Cursor::new(line);                    let mut iter = git_ref::file::log::iter::reverse(read, &mut buf)?;                    let Line {                        previous_oid,                        new_oid,                        signature: _,                        message,                    } = iter.next().expect("a single line")??;                    assert_eq!(previous_oid, hex_to_id("0000000000000000000000000000000000000000"));                    assert_eq!(new_oid, hex_to_id("134385f6d781b7e97062102c6a483440bfda2a03"));                    assert_eq!(message, "commit (initial): c1");                    assert!(iter.next().is_none(), "iterator depleted");                }                Ok(())            }             #[test]            fn two_lines() -> crate::Result {                let two_lines: Vec<u8> = b"1000000000000000000000000000000000000000 234385f6d781b7e97062102c6a483440bfda2a03 committer <committer@example.com> 946771200 +0000	commit (initial): c2\n0000000000000000000000000000000000000000 134385f6d781b7e97062102c6a483440bfda2a03 committer <committer@example.com> 946771200 +0000	commit (initial): c1".to_vec();                let two_lines_trailing_nl = {                    let mut l = two_lines.clone();                    l.push(b'\n');                    l                };                let lines = [two_lines, two_lines_trailing_nl];                for buf_size in &[1024usize, 256] {                    let mut buf = vec![0; *buf_size];                    for line in &lines {                        let read = std::io::Cursor::new(line);                        let mut iter = git_ref::file::log::iter::reverse(read, &mut buf)?;                        let Line {                            previous_oid,                            new_oid,                            signature: _,                            message,                        } = iter.next().expect("a single line")??;                        assert_eq!(previous_oid, hex_to_id("0000000000000000000000000000000000000000"));                        assert_eq!(new_oid, hex_to_id("134385f6d781b7e97062102c6a483440bfda2a03"));                        assert_eq!(message, "commit (initial): c1");                        let Line {                            previous_oid,                            new_oid,                            signature: _,                            message,                        } = iter.next().expect("a single line")??;                        assert_eq!(message, "commit (initial): c2");                        assert_eq!(previous_oid, hex_to_id("1000000000000000000000000000000000000000"));                        assert_eq!(new_oid, hex_to_id("234385f6d781b7e97062102c6a483440bfda2a03"));                        assert!(iter.next().is_none(), "iterator depleted");                    }                }                Ok(())            }        }    }    mod forward {        use bstr::B;        use git_hash::ObjectId;         use crate::file::log::iter::reflog;         #[test]        fn all_success() -> crate::Result {            let log = reflog("HEAD")?;            let iter = git_ref::file::log::iter::forward(&log);            assert_eq!(iter.count(), 5, "the log as a known amount of entries");             let mut iter = git_ref::file::log::iter::forward(&log);            let line = iter.next().unwrap()?;            assert_eq!(line.previous_oid(), ObjectId::null_sha1());            assert_eq!(line.new_oid, B("134385f6d781b7e97062102c6a483440bfda2a03"));            assert_eq!(line.message, B("commit (initial): c1"));            assert!(iter.all(|l| l.is_ok()), "all lines parse fine");            Ok(())        }         #[test]        fn a_single_failure_does_not_abort_iteration() {            let log_first_broken = "0000000000000000000000000000000000000000 134385fbroken7062102c6a483440bfda2a03 committer <committer@example.com> 946771200 +0000	commit0000000000000000000000000000000000000000 134385f6d781b7e97062102c6a483440bfda2a03 committer <committer@example.com> 946771200 +0000	commit (initial): c1\n";             let mut iter = git_ref::file::log::iter::forward(log_first_broken.as_bytes());            let err = iter.next().expect("error is not none").expect_err("the line is broken");            assert_eq!(err.to_string(), "In line 1: \"0000000000000000000000000000000000000000 134385fbroken7062102c6a483440bfda2a03 committer <committer@example.com> 946771200 +0000\\tcommit\" did not match '<old-hexsha> <new-hexsha> <name> <<email>> <timestamp> <tz>\\t<message>'");            assert!(iter.next().expect("a second line").is_ok(), "line parses ok");            assert!(iter.next().is_none(), "iterator exhausted");        }    }}