mod method {    mod from_offsets_in_pack {        use std::sync::atomic::AtomicBool;         use git_odb::pack;         use crate::{            fixture_path,            pack::{INDEX_V1, PACK_FOR_INDEX_V1, SMALL_PACK, SMALL_PACK_INDEX},        };         #[test]        fn v1() -> Result<(), Box<dyn std::error::Error>> {            tree(INDEX_V1, PACK_FOR_INDEX_V1)        }         #[test]        fn v2() -> Result<(), Box<dyn std::error::Error>> {            tree(SMALL_PACK_INDEX, SMALL_PACK)        }         fn tree(index_path: &str, pack_path: &str) -> Result<(), Box<dyn std::error::Error>> {            let idx = pack::index::File::at(fixture_path(index_path))?;            pack::tree::Tree::from_offsets_in_pack(                idx.sorted_offsets().into_iter(),                |ofs| *ofs,                fixture_path(pack_path),                git_features::progress::Discard,                &AtomicBool::new(false),                |id| idx.lookup(id).map(|index| idx.pack_offset_at_index(index)),            )?;            Ok(())        }    }} struct TreeItem<D> {    _offset: u64,    _data: D,    _children: Vec<usize>,} #[test]fn using_option_as_data_does_not_increase_size_in_memory() {    struct Entry {        pub _id: Option<git_hash::ObjectId>,        pub _crc32: u32,    }     struct TreeItemOption<D> {        _offset: u64,        _data: Option<D>,        _children: Vec<usize>,    }    assert_eq!(        std::mem::size_of::<TreeItem<Entry>>(),        std::mem::size_of::<TreeItemOption<Entry>>(),        "we hope niche filling optimizations kick in for our data structures to not pay for the Option at all"    );    assert_eq!(        std::mem::size_of::<[TreeItemOption<Entry>; 7_500_000]>(),        480_000_000,        "it should be as small as possible"    );} #[test]fn size_of_pack_verify_data_structure() {    use git_odb::pack;    pub struct EntryWithDefault {        _index_entry: pack::index::Entry,        _kind: git_object::Kind,        _object_size: u64,        _decompressed_size: u64,        _compressed_size: u64,        _header_size: u16,        _level: u16,    }     assert_eq!(        std::mem::size_of::<[TreeItem<EntryWithDefault>; 7_500_000]>(),        780_000_000    );}