vamp/tests/repository.rs

#![cfg(unix)]

use std::{
    collections::BTreeMap,
    ffi::OsString,
    fs,
    os::unix::{
        ffi::OsStringExt,
        fs::{PermissionsExt, symlink},
    },
    path::{Path, PathBuf},
    process::{Command, Output},
    sync::{
        Arc,
        atomic::{AtomicBool, AtomicU64, Ordering},
    },
};
use vamp::{
    diff::{Category, Comparison, ComparisonMode, FileStatus, RepoKind, Revision, RevisionTarget},
    repository::{CheckoutRefresh, Repository},
};

static NEXT: AtomicU64 = AtomicU64::new(0);
struct Fixture(PathBuf);
impl Fixture {
    fn new() -> Self {
        let path = std::env::temp_dir().join(format!(
            "vamp-repository-test-{}-{}",
            std::process::id(),
            NEXT.fetch_add(1, Ordering::Relaxed)
        ));
        fs::create_dir(&path).unwrap();
        Self(path)
    }
    fn dir(&self, name: &str) -> PathBuf {
        let path = self.0.join(name);
        fs::create_dir(&path).unwrap();
        path
    }
}
impl Drop for Fixture {
    fn drop(&mut self) {
        let _ = fs::remove_dir_all(&self.0);
    }
}
fn command(program: &str, root: &Path, args: &[&str]) -> Output {
    Command::new(program)
        .current_dir(root)
        .args(args)
        .env("GIT_CONFIG_NOSYSTEM", "1")
        .env("GIT_CONFIG_GLOBAL", "/dev/null")
        .env("GIT_OPTIONAL_LOCKS", "0")
        .env("GIT_TERMINAL_PROMPT", "0")
        .env("GIT_AUTHOR_DATE", "2000-01-01T00:00:00Z")
        .env("GIT_COMMITTER_DATE", "2000-01-01T00:00:00Z")
        .env("JJ_CONFIG", "/dev/null")
        .env("JJ_USER", "Diff Test")
        .env("JJ_EMAIL", "diff@example.invalid")
        .output()
        .unwrap()
}
fn success(program: &str, root: &Path, args: &[&str]) -> String {
    let result = command(program, root, args);
    assert!(
        result.status.success(),
        "{program} {args:?}: {}",
        String::from_utf8_lossy(&result.stderr)
    );
    String::from_utf8(result.stdout)
        .unwrap()
        .trim_end_matches('\n')
        .into()
}
fn git(root: &Path, args: &[&str]) -> String {
    success("git", root, args)
}
fn jj(root: &Path, args: &[&str]) -> String {
    success("jj", root, args)
}
fn init_git(root: &Path) {
    git(root, &["init", "--initial-branch=local"]);
    git(root, &["config", "user.name", "Diff Test"]);
    git(root, &["config", "user.email", "diff@example.invalid"]);
}
fn init_jj(root: &Path, colocate: bool) {
    jj(
        root,
        &[
            "git",
            "init",
            if colocate {
                "--colocate"
            } else {
                "--no-colocate"
            },
        ],
    );
    jj(root, &["config", "set", "--repo", "user.name", "Diff Test"]);
    jj(
        root,
        &[
            "config",
            "set",
            "--repo",
            "user.email",
            "diff@example.invalid",
        ],
    );
}
fn open(root: &Path) -> Repository {
    Repository::open(root, Arc::new(AtomicBool::new(false))).unwrap()
}
fn revision(id: &str, kind: RepoKind) -> Revision {
    Revision {
        target: RevisionTarget::Commit(id.into()),
        label: id.into(),
        description: String::new(),
        category: if kind == RepoKind::Jujutsu {
            Category::Revisions
        } else {
            Category::Commits
        },
    }
}
fn working(kind: RepoKind) -> Revision {
    let mut r = revision("working", kind);
    r.target = RevisionTarget::Working;
    r
}

fn checkout_comparison(refresh: CheckoutRefresh) -> Comparison {
    let CheckoutRefresh::Checkout(comparison) = refresh else {
        panic!("Expected checkout-only refresh");
    };
    comparison
}

fn compare_loaded(
    repository: &mut Repository,
    before: &Revision,
    after: &Revision,
    buffers: &[(PathBuf, String)],
) -> Result<Comparison, String> {
    let mut comparison =
        repository.compare(1, before, after, ComparisonMode::Snapshots, buffers)?;
    for (index, file) in comparison.files.iter_mut().enumerate() {
        *file = repository.load_file(1, index)?;
        if file
            .notice
            .as_deref()
            .is_some_and(|notice| notice.contains("Binary or non-UTF-8"))
        {
            comparison.editable_paths.remove(&file.path);
        }
    }
    Ok(comparison)
}
fn changed<'a>(comparison: &'a Comparison, path: &Path) -> &'a vamp::diff::ChangedFile {
    comparison
        .files
        .iter()
        .find(|f| f.path == path)
        .unwrap_or_else(|| panic!("Missing changed file {path:?}: {:?}", comparison.files))
}
// Capture active metadata, checkout bytes, executable bits and link targets. Access
// times are intentionally excluded: reading a repository must not change its data.
fn disk_state(root: &Path) -> BTreeMap<PathBuf, (u32, Vec<u8>)> {
    fn visit(root: &Path, path: &Path, result: &mut BTreeMap<PathBuf, (u32, Vec<u8>)>) {
        for entry in fs::read_dir(path).unwrap() {
            let entry = entry.unwrap();
            let full = entry.path();
            let metadata = fs::symlink_metadata(&full).unwrap();
            if metadata.is_dir() {
                visit(root, &full, result);
            } else {
                let data = if metadata.file_type().is_symlink() {
                    use std::os::unix::ffi::OsStrExt;
                    fs::read_link(&full)
                        .unwrap()
                        .as_os_str()
                        .as_bytes()
                        .to_vec()
                } else {
                    fs::read(&full).unwrap()
                };
                result.insert(
                    full.strip_prefix(root).unwrap().to_path_buf(),
                    (metadata.permissions().mode(), data),
                );
            }
        }
    }
    let mut result = BTreeMap::new();
    visit(root, root, &mut result);
    result
}

#[test]
fn comparison_revisions_freeze_commits_and_address_working_contents() {
    for kind in [RepoKind::Git, RepoKind::Jujutsu] {
        let fixture = Fixture::new();
        let root = fixture.dir("identity").canonicalize().unwrap();
        match kind {
            RepoKind::Git => init_git(&root),
            RepoKind::Jujutsu => init_jj(&root, false),
        }
        fs::write(root.join("file"), "committed\n").unwrap();
        let id = match kind {
            RepoKind::Git => {
                git(&root, &["add", "."]);
                git(&root, &["commit", "-m", "baseline"]);
                git(&root, &["rev-parse", "HEAD"])
            }
            RepoKind::Jujutsu => {
                jj(&root, &["describe", "-m", "baseline"]);
                jj(&root, &["log", "--no-graph", "-r", "@", "-T", "commit_id"])
            }
        };
        fs::write(root.join("file"), "working\n").unwrap();
        let state = disk_state(&root);
        let before = revision(&id, kind);
        let after = working(kind);
        let mut repository = open(&root);
        let first = repository
            .compare(1, &before, &after, ComparisonMode::Snapshots, &[])
            .unwrap();
        assert_eq!(first.revisions[0], id);
        assert!(first.revisions[1].starts_with("working:"));
        assert_eq!(first.blame[0].as_ref().unwrap().commit, id);
        assert_eq!(
            first.blame[1]
                .as_ref()
                .map(|baseline| baseline.commit.as_str()),
            (kind == RepoKind::Git).then_some(id.as_str())
        );
        let reopened = open(&root)
            .compare(2, &before, &after, ComparisonMode::Snapshots, &[])
            .unwrap();
        assert_eq!(first.revisions, reopened.revisions);
        let overlay = repository
            .compare(
                3,
                &before,
                &after,
                ComparisonMode::Snapshots,
                &[(root.join("file"), "unsaved\n".into())],
            )
            .unwrap();
        assert_ne!(overlay.revisions[1], first.revisions[1]);
        let repeated = repository
            .compare(
                4,
                &before,
                &after,
                ComparisonMode::Snapshots,
                &[(root.join("file"), "unsaved\n".into())],
            )
            .unwrap();
        assert_eq!(repeated.revisions, overlay.revisions);
        let working_pair = repository
            .compare(5, &after, &after, ComparisonMode::Snapshots, &[])
            .unwrap();
        assert_eq!(working_pair.revisions[0], first.revisions[1]);
        assert_eq!(working_pair.revisions[0], working_pair.revisions[1]);
        assert_eq!(
            working_pair.blame,
            [first.blame[1].clone(), first.blame[1].clone()]
        );
        assert_eq!(disk_state(&root), state);
        fs::write(root.join("file"), "working").unwrap();
        let no_newline = repository
            .compare(6, &before, &after, ComparisonMode::Snapshots, &[])
            .unwrap();
        assert_ne!(no_newline.revisions[1], first.revisions[1]);
    }
}

#[test]
fn unopened_catalog_counts_frozen_text_but_not_binary_modes_or_exact_renames() {
    let fixture = Fixture::new();
    let root = fixture.dir("stats");
    init_git(&root);
    for (path, bytes) in [
        ("first", &b"old\nkeep\n"[..]),
        ("second", b"remove\nkeep\n"),
        ("removed", b"gone\n"),
        ("rename-old", b"move\n"),
        ("binary", b"\0old"),
        ("mode", b"script\n"),
        ("crlf", b"a\r\n"),
        ("eof", b"same\n"),
    ] {
        fs::write(root.join(path), bytes).unwrap();
    }
    git(&root, &["add", "."]);
    git(&root, &["commit", "-m", "before"]);
    let before = revision(&git(&root, &["rev-parse", "HEAD"]), RepoKind::Git);
    for (path, bytes) in [
        ("first", &b"new\nextra\nkeep\n"[..]),
        ("second", b"keep\n"),
        ("added", b"one\nlast"),
        ("binary", b"\0new"),
        ("crlf", b"b\r\n"),
        ("eof", b"same"),
    ] {
        fs::write(root.join(path), bytes).unwrap();
    }
    fs::remove_file(root.join("removed")).unwrap();
    fs::rename(root.join("rename-old"), root.join("-renamed\t\n")).unwrap();
    fs::set_permissions(root.join("mode"), fs::Permissions::from_mode(0o755)).unwrap();
    let mut repository = open(&root);
    let catalog = repository
        .compare(
            1,
            &before,
            &working(RepoKind::Git),
            ComparisonMode::Snapshots,
            &[],
        )
        .unwrap();
    assert!(catalog.files.iter().all(|file| !file.loaded
        && file.before.is_empty()
        && file.after.is_empty()
        && file.hunks.is_empty()));
    for (path, counts) in [
        ("first", (2, 1)),
        ("second", (0, 1)),
        ("added", (2, 0)),
        ("removed", (0, 1)),
        ("-renamed\t\n", (0, 0)),
        ("binary", (0, 0)),
        ("mode", (0, 0)),
        ("crlf", (1, 1)),
        ("eof", (1, 1)),
    ] {
        assert_eq!(
            changed(&catalog, Path::new(path)).stats,
            Some(counts),
            "{path}"
        );
    }
    assert_eq!(
        changed(&catalog, Path::new("-renamed\t\n")).status,
        FileStatus::Renamed
    );
    fs::write(root.join("second"), "changed after freezing\n").unwrap();
    for (index, file) in catalog.files.iter().enumerate() {
        let loaded = repository.load_file(1, index).unwrap();
        let counts = loaded.hunks.iter().fold((0, 0), |(added, removed), hunk| {
            (added + hunk.after_len, removed + hunk.before_len)
        });
        assert_eq!(file.stats, Some(counts), "{}", file.path.display());
    }
    git(&root, &["add", "-A"]);
    git(&root, &["commit", "-m", "advance checkout"]);
    let refreshed = repository
        .refresh_checkout(1, 2, true, &[])
        .unwrap()
        .map(checkout_comparison)
        .unwrap();
    assert_eq!(changed(&refreshed, Path::new("first")).stats, Some((2, 1)));
    assert_eq!(changed(&refreshed, Path::new("second")).stats, Some((1, 2)));
}

#[test]
fn git_working_reads_disk_and_handles_ranges_ignored_files_binary_links_and_odd_paths() {
    let fixture = Fixture::new();
    let root = fixture.dir("git");
    init_git(&root);
    for (path, data) in [
        ("text", &b"one\nthree\n"[..]),
        ("removed", b"removed\n"),
        ("empty-before", b""),
        ("newline", b"same\n"),
        ("crlf", b"a\r\n"),
        ("rename-old", b"move\n"),
        ("binary", b"\0old"),
        ("ignored-tracked", b"old\n"),
        ("executable", b"script\n"),
        ("type-switch", b"target"),
        (".gitignore", b"ignored-*\n"),
    ] {
        fs::write(root.join(path), data).unwrap();
    }
    git(&root, &["add", "."]);
    git(&root, &["add", "--force", "ignored-tracked"]);
    git(&root, &["commit", "-m", "baseline"]);
    git(&root, &["tag", "-a", "annotated", "-m", "tag"]);
    git(
        &root,
        &["tag", "-a", "nested", "-m", "nested tag", "annotated"],
    );
    let id = git(&root, &["rev-parse", "HEAD"]);
    fs::write(root.join("text"), b"one\nstaged\nthree\n").unwrap();
    git(&root, &["add", "text"]);
    fs::write(root.join("text"), b"one\ntwo\nthree\n").unwrap();
    fs::remove_file(root.join("removed")).unwrap();
    fs::write(root.join("empty-before"), b"first\n").unwrap();
    fs::write(root.join("empty-added"), b"").unwrap();
    fs::write(root.join("added"), b"added\n").unwrap();
    fs::write(root.join("newline"), b"same").unwrap();
    fs::write(root.join("crlf"), b"b\r\n").unwrap();
    fs::write(root.join("binary"), b"\0new").unwrap();
    fs::write(root.join("ignored-tracked"), b"changed\n").unwrap();
    fs::write(root.join("ignored-untracked"), b"must not appear\n").unwrap();
    fs::rename(root.join("rename-old"), root.join("rename-new")).unwrap();
    fs::remove_file(root.join("type-switch")).unwrap();
    symlink("target", root.join("type-switch")).unwrap();
    fs::set_permissions(root.join("executable"), fs::Permissions::from_mode(0o755)).unwrap();
    let odd = PathBuf::from("-tab\tand\nnewline");
    fs::write(root.join(&odd), b"odd\n").unwrap();
    let non_utf8 = PathBuf::from(OsString::from_vec(b"non-utf8-\xff".to_vec()));
    let non_utf8_created = match fs::write(root.join(&non_utf8), b"bytes\n") {
        Ok(()) => true,
        // APFS rejects non-UTF-8 names before repository code can read them.
        Err(error) if cfg!(target_os = "macos") && error.raw_os_error() == Some(92) => false,
        Err(error) => panic!("Cannot create non-UTF-8 fixture: {error}"),
    };
    symlink("/not/a/path/to/read", root.join("link")).unwrap();
    let state = disk_state(&root);
    let mut repository = open(&root);
    let catalog = repository.catalog().unwrap();
    assert_eq!(catalog.kind, RepoKind::Git);
    assert_eq!(catalog.entries[0].target, RevisionTarget::Working);
    assert!(
        catalog
            .entries
            .iter()
            .any(|r| r.label == id && r.description == "baseline")
    );
    assert!(catalog.entries.iter().any(|r| r.label == "nested"
        && r.category == Category::Tags
        && r.target == RevisionTarget::Commit(id.clone())));
    let comparison = compare_loaded(
        &mut repository,
        &revision(&id, RepoKind::Git),
        &working(RepoKind::Git),
        &[],
    )
    .unwrap();
    let text = changed(&comparison, Path::new("text"));
    assert_eq!(comparison.root, fs::canonicalize(&root).unwrap());
    assert!(comparison.editable_paths.contains(Path::new("text")));
    assert!(comparison.editable_paths.contains(Path::new("empty-added")));
    for path in ["binary", "link", "removed", "type-switch"] {
        assert!(!comparison.editable_paths.contains(Path::new(path)));
    }
    assert_eq!(text.after, ["one", "two", "three"]);
    assert_eq!(
        (
            text.hunks[0].before_start,
            text.hunks[0].before_len,
            text.hunks[0].after_start,
            text.hunks[0].after_len
        ),
        (1, 0, 1, 1)
    );
    let empty = changed(&comparison, Path::new("empty-before"));
    assert_eq!(
        (
            empty.hunks[0].before_start,
            empty.hunks[0].before_len,
            empty.hunks[0].after_start,
            empty.hunks[0].after_len
        ),
        (0, 0, 0, 1)
    );
    let deleted = changed(&comparison, Path::new("removed"));
    assert_eq!(deleted.status, FileStatus::Removed);
    assert_eq!(
        (
            deleted.hunks[0].before_start,
            deleted.hunks[0].before_len,
            deleted.hunks[0].after_start,
            deleted.hunks[0].after_len
        ),
        (0, 1, 0, 0)
    );
    assert_eq!(
        changed(&comparison, Path::new("empty-added")).status,
        FileStatus::Added
    );
    assert!(
        changed(&comparison, Path::new("empty-added"))
            .after
            .is_empty()
    );
    assert_eq!(changed(&comparison, &odd).after, ["odd"]);
    if non_utf8_created {
        assert_eq!(changed(&comparison, &non_utf8).after, ["bytes"]);
    }
    assert_eq!(changed(&comparison, Path::new("crlf")).after, ["b\r"]);
    assert!(
        changed(&comparison, Path::new("newline"))
            .notice
            .as_ref()
            .unwrap()
            .contains("EOF newline")
    );
    let type_switch = changed(&comparison, Path::new("type-switch"));
    assert_eq!(type_switch.before, type_switch.after);
    assert!(
        type_switch
            .notice
            .as_ref()
            .unwrap()
            .contains("100644 → 120000")
    );
    let binary = changed(&comparison, Path::new("binary"));
    assert!(binary.before.is_empty() && binary.after.is_empty() && binary.hunks.is_empty());
    assert!(binary.notice.as_ref().unwrap().contains("Binary"));
    assert_eq!(
        changed(&comparison, Path::new("link")).after,
        ["/not/a/path/to/read"]
    );
    assert!(
        changed(&comparison, Path::new("link"))
            .notice
            .as_ref()
            .unwrap()
            .contains("Symbolic link")
    );
    assert!(
        changed(&comparison, Path::new("executable"))
            .notice
            .as_ref()
            .unwrap()
            .contains("mode changed")
    );
    assert_eq!(
        changed(&comparison, Path::new("ignored-tracked")).after,
        ["changed"]
    );
    assert!(
        !comparison
            .files
            .iter()
            .any(|f| f.path == Path::new("ignored-untracked"))
    );
    let moved = changed(&comparison, Path::new("rename-new"));
    assert_eq!(moved.status, FileStatus::Renamed);
    assert_eq!(moved.old_path.as_deref(), Some(Path::new("rename-old")));
    assert_eq!(moved.before, moved.after);
    assert!(moved.hunks.is_empty());
    let reverse = compare_loaded(
        &mut repository,
        &working(RepoKind::Git),
        &revision(&id, RepoKind::Git),
        &[],
    )
    .unwrap();
    assert!(reverse.editable_paths.contains(Path::new("text")));
    assert!(!reverse.editable_paths.contains(Path::new("added")));
    assert!(!reverse.editable_paths.contains(Path::new("link")));
    assert_eq!(changed(&reverse, Path::new("text")).after, ["one", "three"]);
    assert_eq!(
        changed(&reverse, Path::new("added")).status,
        FileStatus::Removed
    );
    assert!(
        repository
            .compare(
                1,
                &working(RepoKind::Git),
                &working(RepoKind::Git),
                ComparisonMode::Snapshots,
                &[]
            )
            .unwrap()
            .files
            .is_empty()
    );
    assert_eq!(disk_state(&root), state);
}

#[test]
fn git_remote_refs_and_annotated_tags_are_discovered_before_fetch_and_history_stays_private() {
    let fixture = Fixture::new();
    let source = fixture.dir("source");
    init_git(&source);
    fs::write(source.join("file"), "ancestor\n").unwrap();
    git(&source, &["add", "."]);
    git(&source, &["commit", "-m", "remote ancestor needle"]);
    let ancestor = git(&source, &["rev-parse", "HEAD"]);
    git(&source, &["tag", "-a", "ancestor-tag", "-m", "annotated"]);
    fs::write(source.join("file"), "remote tip\n").unwrap();
    git(&source, &["commit", "-am", "remote tip"]);
    let tip = git(&source, &["rev-parse", "HEAD"]);
    git(&source, &["branch", "never-fetched"]);
    let bare = fixture.0.join("remote.git");
    git(
        &fixture.0,
        &[
            "clone",
            "--bare",
            source.to_str().unwrap(),
            bare.to_str().unwrap(),
        ],
    );
    let active = fixture.dir("active");
    init_git(&active);
    fs::write(active.join("file"), "local\n").unwrap();
    git(&active, &["add", "."]);
    git(&active, &["commit", "-m", "local"]);
    let local = git(&active, &["rev-parse", "HEAD"]);
    git(
        &active,
        &["remote", "add", "origin", bare.to_str().unwrap()],
    );
    let state = disk_state(&active);
    let mut repository = open(&active);
    let catalog = repository.list_remote("origin").unwrap();
    let remote = catalog
        .entries
        .iter()
        .find(|r| {
            r.target
                == (RevisionTarget::Remote {
                    remote: "origin".into(),
                    reference: "refs/heads/never-fetched".into(),
                })
        })
        .unwrap()
        .clone();
    let tag = catalog
        .entries
        .iter()
        .find(|r| {
            r.target
                == (RevisionTarget::Remote {
                    remote: "origin".into(),
                    reference: "refs/tags/ancestor-tag".into(),
                })
        })
        .unwrap()
        .clone();
    assert!(
        catalog
            .entries
            .iter()
            .any(|r| r.target == RevisionTarget::FetchRemote("origin".into()))
    );
    assert!(
        !catalog
            .entries
            .iter()
            .any(|r| r.target == RevisionTarget::Commit(ancestor.clone()))
    );
    assert!(
        !command("git", &active, &["cat-file", "-e", &tip])
            .status
            .success()
    );
    let comparison = compare_loaded(
        &mut repository,
        &revision(&local, RepoKind::Git),
        &remote,
        &[(active.join("file"), "unsaved local text\n".into())],
    )
    .unwrap();
    assert!(comparison.editable_paths.is_empty());
    assert_eq!(changed(&comparison, Path::new("file")).before, ["local"]);
    assert_eq!(
        changed(&comparison, Path::new("file")).after,
        ["remote tip"]
    );
    let comparison = compare_loaded(&mut repository, &tag, &remote, &[]).unwrap();
    assert_eq!(changed(&comparison, Path::new("file")).before, ["ancestor"]);
    let comparison =
        compare_loaded(&mut repository, &remote, &working(RepoKind::Git), &[]).unwrap();
    assert_eq!(changed(&comparison, Path::new("file")).after, ["local"]);
    let loaded = repository.fetch_remote("origin").unwrap();
    let historic = loaded
        .entries
        .iter()
        .find(|r| {
            r.target == RevisionTarget::Commit(ancestor.clone()) && r.category == Category::Commits
        })
        .unwrap();
    assert_eq!(historic.label, ancestor);
    assert_eq!(historic.description, "remote ancestor needle");
    let comparison = compare_loaded(
        &mut repository,
        historic,
        &revision(&local, RepoKind::Git),
        &[],
    )
    .unwrap();
    assert_eq!(changed(&comparison, Path::new("file")).before, ["ancestor"]);
    assert!(
        !command("git", &active, &["cat-file", "-e", &tip])
            .status
            .success()
    );
    assert_eq!(disk_state(&active), state);
    // An advertised remote alias already available at HEAD is eligible without
    // importing refs or substituting the local unsaved overlay for pinned bytes.
    git(
        &source,
        &["remote", "add", "origin", bare.to_str().unwrap()],
    );
    let source_state = disk_state(&source);
    let mut checked_out = open(&source);
    let advertised = checked_out.list_remote("origin").unwrap();
    let alias = advertised
        .entries
        .iter()
        .find(|entry| entry.target == remote.target)
        .unwrap();
    let pinned = checked_out
        .compare(
            20,
            &revision(&ancestor, RepoKind::Git),
            alias,
            ComparisonMode::Snapshots,
            &[(source.join("file"), "dirty live\n".into())],
        )
        .unwrap();
    assert!(pinned.editable_paths.contains(Path::new("file")));
    assert_eq!(checked_out.load_file(20, 0).unwrap().after, ["remote tip"]);
    assert_eq!(disk_state(&source), source_state);
    git(&source, &["checkout", "--detach", &ancestor]);
    let readonly = checked_out
        .refresh_checkout(20, 21, false, &[])
        .unwrap()
        .map(checkout_comparison)
        .unwrap();
    assert!(readonly.editable_paths.is_empty());
    assert_eq!(checked_out.load_file(21, 0).unwrap().after, ["remote tip"]);
    git(&source, &["checkout", "--detach", &tip]);
    let promoted = checked_out
        .refresh_checkout(21, 22, false, &[])
        .unwrap()
        .map(checkout_comparison)
        .unwrap();
    assert_eq!(promoted.editable_paths, pinned.editable_paths);
    assert_eq!(checked_out.load_file(22, 0).unwrap().after, ["remote tip"]);
}

#[test]
fn jj_catalog_and_working_comparisons_prefer_jj_and_never_snapshot_or_merge_operations() {
    for colocate in [false, true] {
        let fixture = Fixture::new();
        let active = fixture.dir("active");
        init_jj(&active, colocate);
        fs::write(active.join("file"), "baseline\n").unwrap();
        fs::write(active.join("deleted"), "delete\n").unwrap();
        fs::write(active.join(".gitignore"), "ignored-*\n").unwrap();
        jj(&active, &["describe", "-m", "jj baseline searchable"]);
        let id = jj(
            &active,
            &[
                "--ignore-working-copy",
                "--at-operation=@",
                "log",
                "--no-graph",
                "-r",
                "@",
                "-T",
                "commit_id",
            ],
        );
        jj(&active, &["bookmark", "create", "baseline"]);
        jj(&active, &["new"]);
        fs::write(active.join("file"), "disk\n").unwrap();
        fs::remove_file(active.join("deleted")).unwrap();
        fs::write(active.join("addition"), "new\n").unwrap();
        fs::write(active.join("ignored-untracked"), "ignored\n").unwrap();
        let state = disk_state(&active);
        let mut repository = open(&active);
        let catalog = repository.catalog().unwrap();
        assert_eq!(catalog.kind, RepoKind::Jujutsu);
        let baseline = catalog
            .entries
            .iter()
            .find(|r| {
                r.target == RevisionTarget::Commit(id.clone()) && r.category == Category::Revisions
            })
            .unwrap();
        assert!(
            catalog
                .entries
                .iter()
                .any(|r| r.label == "baseline" && r.category == Category::Bookmarks)
        );
        let comparison =
            compare_loaded(&mut repository, baseline, &working(RepoKind::Jujutsu), &[]).unwrap();
        assert_eq!(changed(&comparison, Path::new("file")).after, ["disk"]);
        assert_eq!(
            changed(&comparison, Path::new("deleted")).status,
            FileStatus::Removed
        );
        assert_eq!(
            changed(&comparison, Path::new("addition")).status,
            FileStatus::Added
        );
        assert!(
            !comparison
                .files
                .iter()
                .any(|f| f.path == Path::new("ignored-untracked"))
        );
        let synthetic_root = revision(&"0".repeat(40), RepoKind::Jujutsu);
        let branch = repository
            .compare(
                20,
                &synthetic_root,
                baseline,
                ComparisonMode::BranchChanges,
                &[],
            )
            .unwrap();
        assert!(branch.before.ends_with(&"0".repeat(40)));
        assert!(
            branch
                .files
                .iter()
                .any(|file| file.path == Path::new("file"))
        );
        let reversed = repository
            .compare(
                21,
                baseline,
                &synthetic_root,
                ComparisonMode::BranchChanges,
                &[],
            )
            .unwrap();
        assert!(reversed.files.is_empty());
        assert!(
            repository
                .compare(22, baseline, baseline, ComparisonMode::BranchChanges, &[])
                .unwrap()
                .files
                .is_empty()
        );
        assert_eq!(disk_state(&active), state);
    }
}

#[test]
fn jj_bookmark_refresh_tracks_movement_and_same_change_rewrites_without_touching_source() {
    for colocate in [false, true] {
        let fixture = Fixture::new();
        let root = fixture.dir("bookmarks");
        init_jj(&root, colocate);
        fs::write(root.join("file"), "base\n").unwrap();
        jj(&root, &["describe", "-m", "base"]);
        let base = jj(&root, &["log", "--no-graph", "-r", "@", "-T", "commit_id"]);
        jj(&root, &["bookmark", "create", "topic"]);
        jj(&root, &["new"]);
        fs::write(root.join("file"), "next\n").unwrap();
        jj(&root, &["describe", "-m", "next"]);
        let next = jj(&root, &["log", "--no-graph", "-r", "@", "-T", "commit_id"]);
        let mut repository = open(&root);
        let catalog = repository.catalog().unwrap();
        let topic = catalog
            .entries
            .iter()
            .find(|entry| entry.label == "topic")
            .unwrap();
        assert_eq!(
            topic.target,
            RevisionTarget::Bookmark {
                name: "topic".into(),
                remote: None
            }
        );
        repository
            .compare(
                1,
                &revision(&"0".repeat(40), RepoKind::Jujutsu),
                topic,
                ComparisonMode::Snapshots,
                &[],
            )
            .unwrap();
        jj(&root, &["bookmark", "set", "topic", "-r", &next]);
        let state = disk_state(&root);
        let Some(CheckoutRefresh::Bookmark(comparison)) =
            repository.refresh_checkout(1, 2, false, &[]).unwrap()
        else {
            panic!("Bookmark movement must replace contents even when follow is disabled");
        };
        assert_eq!(comparison.after, topic.label);
        assert!(comparison.blame[0].is_none());
        assert_eq!(comparison.blame[1].as_ref().unwrap().commit, next);
        assert_eq!(repository.load_file(2, 0).unwrap().after, ["next"]);
        assert!(repository.load_file(1, 0).is_err());
        assert!(
            repository
                .refresh_checkout(2, 3, false, &[])
                .unwrap()
                .is_none()
        );
        assert_eq!(disk_state(&root), state);
        let change = jj(&root, &["log", "--no-graph", "-r", "@", "-T", "change_id"]);
        fs::write(root.join("file"), "rewritten\n").unwrap();
        jj(&root, &["describe", "-m", "rewritten"]);
        assert_eq!(
            jj(&root, &["log", "--no-graph", "-r", "@", "-T", "change_id"]),
            change
        );
        let state = disk_state(&root);
        assert!(matches!(
            repository.refresh_checkout(2, 3, false, &[]).unwrap(),
            Some(CheckoutRefresh::Bookmark(_))
        ));
        assert_eq!(repository.load_file(3, 0).unwrap().after, ["rewritten"]);
        assert_eq!(disk_state(&root), state);
        jj(&root, &["describe", "-m", "description-only rewrite"]);
        assert!(matches!(
            repository.refresh_checkout(3, 4, false, &[]).unwrap(),
            Some(CheckoutRefresh::Bookmark(_))
        ));
        assert_eq!(repository.load_file(4, 0).unwrap().after, ["rewritten"]);
        repository
            .compare(
                5,
                &revision(&"0".repeat(40), RepoKind::Jujutsu),
                &revision(&base, RepoKind::Jujutsu),
                ComparisonMode::Snapshots,
                &[],
            )
            .unwrap();
        assert!(
            repository
                .refresh_checkout(5, 6, false, &[])
                .unwrap()
                .is_none()
        );
        assert_eq!(repository.load_file(5, 0).unwrap().after, ["base"]);
    }
}

#[test]
fn jj_bookmark_refresh_retains_frozen_working_before_and_working_after_overlays() {
    let fixture = Fixture::new();
    let root = fixture.dir("bookmark-working").canonicalize().unwrap();
    init_jj(&root, false);
    fs::write(root.join("file"), "base\n").unwrap();
    jj(&root, &["describe", "-m", "base"]);
    jj(&root, &["bookmark", "create", "topic"]);
    jj(&root, &["new"]);
    fs::write(root.join("file"), "frozen disk\n").unwrap();
    let mut repository = open(&root);
    let catalog = repository.catalog().unwrap();
    let topic = catalog
        .entries
        .iter()
        .find(|entry| entry.label == "topic")
        .unwrap();
    repository
        .compare(
            1,
            &working(RepoKind::Jujutsu),
            topic,
            ComparisonMode::Snapshots,
            &[],
        )
        .unwrap();
    fs::write(root.join("file"), "new topic\n").unwrap();
    jj(&root, &["describe", "-m", "next"]);
    jj(&root, &["bookmark", "set", "topic", "-r", "@"]);
    assert!(matches!(
        repository.refresh_checkout(1, 2, false, &[]).unwrap(),
        Some(CheckoutRefresh::Bookmark(_))
    ));
    let file = repository.load_file(2, 0).unwrap();
    assert_eq!(file.before, ["frozen disk"]);
    assert_eq!(file.after, ["new topic"]);
    repository
        .compare(
            3,
            topic,
            &working(RepoKind::Jujutsu),
            ComparisonMode::Snapshots,
            &[(root.join("file"), "old overlay\n".into())],
        )
        .unwrap();
    fs::write(root.join("file"), "rewritten topic\n").unwrap();
    jj(&root, &["describe", "-m", "rewrite"]);
    let state = disk_state(&root);
    assert!(matches!(
        repository
            .refresh_checkout(3, 4, false, &[(root.join("file"), "dirty buffer\n".into())])
            .unwrap(),
        Some(CheckoutRefresh::Bookmark(_))
    ));
    let file = repository.load_file(4, 0).unwrap();
    assert_eq!(file.before, ["rewritten topic"]);
    // Live buffer rebinding is a frontend concern; a bookmark refresh must not
    // advance the unrelated frozen Working endpoint while follow is disabled.
    assert_eq!(file.after, ["old overlay"]);
    assert_eq!(disk_state(&root), state);
    jj(&root, &["new"]);
    fs::write(root.join("file"), "advanced checkout\n").unwrap();
    jj(&root, &["describe", "-m", "advance"]);
    jj(&root, &["bookmark", "set", "topic", "-r", "@"]);
    assert!(matches!(
        repository.refresh_checkout(4, 5, false, &[]).unwrap(),
        Some(CheckoutRefresh::Bookmark(_))
    ));
    assert_eq!(repository.load_file(5, 0).unwrap().after, ["old overlay"]);
    assert!(matches!(
        repository
            .refresh_checkout(5, 6, true, &[(root.join("file"), "new overlay\n".into())])
            .unwrap(),
        Some(CheckoutRefresh::Checkout(_))
    ));
    let file = repository.load_file(6, 0).unwrap();
    assert_eq!(file.before, ["advanced checkout"]);
    assert_eq!(file.after, ["new overlay"]);
}

#[test]
fn jj_bookmark_refresh_recomputes_branch_merge_base_and_recovers_after_deletion() {
    let fixture = Fixture::new();
    let root = fixture.dir("bookmark-branch");
    init_jj(&root, false);
    fs::write(root.join("file"), "base\n").unwrap();
    jj(&root, &["describe", "-m", "base"]);
    let base = jj(&root, &["log", "--no-graph", "-r", "@", "-T", "commit_id"]);
    jj(&root, &["bookmark", "create", "before"]);
    jj(&root, &["new"]);
    fs::write(root.join("file"), "tip\n").unwrap();
    jj(&root, &["describe", "-m", "tip"]);
    let tip = jj(&root, &["log", "--no-graph", "-r", "@", "-T", "commit_id"]);
    jj(&root, &["bookmark", "create", "after"]);
    let mut repository = open(&root);
    let catalog = repository.catalog().unwrap();
    let before = catalog
        .entries
        .iter()
        .find(|entry| entry.label == "before")
        .unwrap();
    let after = catalog
        .entries
        .iter()
        .find(|entry| entry.label == "after")
        .unwrap();
    let original = repository
        .compare(1, before, after, ComparisonMode::BranchChanges, &[])
        .unwrap();
    assert!(original.before.ends_with(&base));
    assert_eq!(original.revisions, [base.clone(), tip.clone()]);
    assert_eq!(original.blame[0].as_ref().unwrap().commit, base);
    assert_eq!(original.blame[1].as_ref().unwrap().commit, tip);
    jj(&root, &["bookmark", "set", "before", "-r", &tip]);
    let Some(CheckoutRefresh::Bookmark(comparison)) =
        repository.refresh_checkout(1, 2, false, &[]).unwrap()
    else {
        panic!("Moved Before must recompute merge base");
    };
    assert!(comparison.before.ends_with(&tip));
    assert_eq!(comparison.revisions, [tip.clone(), tip.clone()]);
    assert_eq!(comparison.blame[0].as_ref().unwrap().commit, tip);
    assert_eq!(comparison.blame[1].as_ref().unwrap().commit, tip);
    assert!(comparison.files.is_empty());
    jj(&root, &["bookmark", "delete", "after"]);
    let state = disk_state(&root);
    assert!(
        repository
            .refresh_checkout(2, 3, false, &[])
            .unwrap_err()
            .contains("missing or deleted")
    );
    assert!(repository.load_file(3, 0).is_err());
    assert_eq!(disk_state(&root), state);
    jj(&root, &["bookmark", "create", "after", "-r", &tip]);
    // A restored bookmark at the same ID is a successful no-op (or eligibility
    // promotion), not another comparison-content replacement.
    assert!(!matches!(
        repository.refresh_checkout(2, 3, false, &[]).unwrap(),
        Some(CheckoutRefresh::Bookmark(_))
    ));
    jj(
        &root,
        &["bookmark", "set", "after", "-r", &base, "--allow-backwards"],
    );
    let Some(CheckoutRefresh::Bookmark(comparison)) =
        repository.refresh_checkout(3, 4, false, &[]).unwrap()
    else {
        panic!("Backward bookmark movement must refresh");
    };
    assert!(comparison.before.ends_with(&base));
    assert!(comparison.files.is_empty());
}

#[test]
fn jj_bookmark_refresh_uses_exact_names_and_keeps_last_view_through_conflicts() {
    let fixture = Fixture::new();
    let root = fixture.dir("bookmark-conflict");
    init_jj(&root, false);
    fs::write(root.join("file"), "base\n").unwrap();
    jj(&root, &["describe", "-m", "base"]);
    let base = jj(&root, &["log", "--no-graph", "-r", "@", "-T", "commit_id"]);
    let name = "topic'quoted";
    let argument = "\"topic'quoted\"";
    jj(&root, &["bookmark", "create", argument]);
    jj(&root, &["bookmark", "create", "topic"]);
    jj(&root, &["new"]);
    fs::write(root.join("file"), "left\n").unwrap();
    jj(&root, &["describe", "-m", "left"]);
    let left = jj(&root, &["log", "--no-graph", "-r", "@", "-T", "commit_id"]);
    jj(&root, &["bookmark", "create", "keep-left"]);
    jj(&root, &["new", &base]);
    fs::write(root.join("file"), "right\n").unwrap();
    jj(&root, &["describe", "-m", "right"]);
    let right = jj(&root, &["log", "--no-graph", "-r", "@", "-T", "commit_id"]);
    let mut repository = open(&root);
    let catalog = repository.catalog().unwrap();
    let selected = catalog
        .entries
        .iter()
        .find(|entry| entry.label == name)
        .unwrap();
    repository
        .compare(
            1,
            &revision(&"0".repeat(40), RepoKind::Jujutsu),
            selected,
            ComparisonMode::Snapshots,
            &[],
        )
        .unwrap();
    jj(&root, &["bookmark", "set", "topic", "-r", &left]);
    assert!(
        repository
            .refresh_checkout(1, 2, false, &[])
            .unwrap()
            .is_none()
    );
    let operation = jj(
        &root,
        &["op", "log", "--no-graph", "--limit", "1", "-T", "id"],
    );
    jj(&root, &["bookmark", "set", argument, "-r", &left]);
    jj(
        &root,
        &[
            &format!("--at-operation={operation}"),
            "bookmark",
            "set",
            argument,
            "-r",
            &right,
        ],
    );
    // Merge the fixture's concurrent operations, not the viewer's read queries.
    jj(&root, &["log", "--no-graph", "-r", "@", "-T", "commit_id"]);
    let state = disk_state(&root);
    assert!(
        repository
            .refresh_checkout(1, 2, false, &[])
            .unwrap_err()
            .contains("conflicted")
    );
    assert_eq!(repository.load_file(1, 0).unwrap().after, ["base"]);
    assert!(repository.load_file(2, 0).is_err());
    assert_eq!(disk_state(&root), state);
    jj(
        &root,
        &[
            "bookmark",
            "set",
            argument,
            "-r",
            &left,
            "--allow-backwards",
        ],
    );
    assert!(matches!(
        repository.refresh_checkout(1, 2, false, &[]).unwrap(),
        Some(CheckoutRefresh::Bookmark(_))
    ));
    assert_eq!(repository.load_file(2, 0).unwrap().after, ["left"]);
}

#[test]
fn jj_known_remote_bookmark_refreshes_locally_but_private_catalog_entries_stay_frozen() {
    let fixture = Fixture::new();
    let source = fixture.dir("source");
    init_jj(&source, false);
    fs::write(source.join("file"), "first\n").unwrap();
    jj(&source, &["describe", "-m", "first"]);
    jj(&source, &["bookmark", "create", "topic"]);
    jj(&source, &["bookmark", "create", "deleted"]);
    jj(&source, &["git", "export"]);
    let root = fixture.dir("active");
    init_jj(&root, false);
    jj(
        &root,
        &[
            "git",
            "remote",
            "add",
            "origin",
            source.join(".jj/repo/store/git").to_str().unwrap(),
        ],
    );
    let mut repository = open(&root);
    let private = repository.fetch_remote("origin").unwrap();
    let frozen = private
        .entries
        .iter()
        .find(|entry| {
            entry.label == "topic@origin" && matches!(entry.target, RevisionTarget::Commit(_))
        })
        .unwrap();
    jj(&root, &["git", "fetch", "--remote", "origin"]);
    jj(&root, &["bookmark", "track", "deleted@origin"]);
    jj(&root, &["bookmark", "delete", "deleted"]);
    let catalog = repository.catalog().unwrap();
    let remote = catalog
        .entries
        .iter()
        .find(|entry| {
            entry.target
                == (RevisionTarget::Bookmark {
                    name: "topic".into(),
                    remote: Some("origin".into()),
                })
        })
        .unwrap();
    repository
        .compare(
            1,
            &revision(&"0".repeat(40), RepoKind::Jujutsu),
            remote,
            ComparisonMode::Snapshots,
            &[],
        )
        .unwrap();
    jj(&source, &["new"]);
    fs::write(source.join("file"), "second\n").unwrap();
    jj(&source, &["describe", "-m", "second"]);
    jj(&source, &["bookmark", "set", "topic", "-r", "@"]);
    jj(&source, &["git", "export"]);
    // Remote movement alone does not cause a network poll by the viewer.
    assert!(
        repository
            .refresh_checkout(1, 2, false, &[])
            .unwrap()
            .is_none()
    );
    jj(&root, &["git", "fetch", "--remote", "origin"]);
    let state = disk_state(&root);
    assert!(matches!(
        repository.refresh_checkout(1, 2, false, &[]).unwrap(),
        Some(CheckoutRefresh::Bookmark(_))
    ));
    assert_eq!(repository.load_file(2, 0).unwrap().after, ["second"]);
    assert_eq!(disk_state(&root), state);
    repository
        .compare(
            3,
            &revision(&"0".repeat(40), RepoKind::Jujutsu),
            frozen,
            ComparisonMode::Snapshots,
            &[],
        )
        .unwrap();
    assert!(
        repository
            .refresh_checkout(3, 4, false, &[])
            .unwrap()
            .is_none()
    );
    assert_eq!(repository.load_file(3, 0).unwrap().after, ["first"]);
}

#[test]
fn jj_private_fetch_discovers_never_fetched_bookmark_and_searchable_remote_change_history() {
    let fixture = Fixture::new();
    let source = fixture.dir("source");
    init_jj(&source, false);
    fs::write(source.join("file"), "remote ancestor\n").unwrap();
    jj(&source, &["describe", "-m", "remote historic needle"]);
    let ancestor = jj(
        &source,
        &[
            "--ignore-working-copy",
            "log",
            "--no-graph",
            "-r",
            "@",
            "-T",
            "commit_id",
        ],
    );
    jj(&source, &["new"]);
    fs::write(source.join("file"), "remote tip\n").unwrap();
    jj(&source, &["describe", "-m", "remote tip"]);
    let tip = jj(
        &source,
        &[
            "--ignore-working-copy",
            "log",
            "--no-graph",
            "-r",
            "@",
            "-T",
            "commit_id",
        ],
    );
    jj(&source, &["bookmark", "create", "never-fetched"]);
    let bare = fixture.dir("remote.git");
    jj(&source, &["git", "export"]);
    // Build remote fixture data by copying exported refs, never by pushing.
    git(
        &fixture.0,
        &[
            "clone",
            "--bare",
            "--no-hardlinks",
            source.join(".jj/repo/store/git").to_str().unwrap(),
            bare.to_str().unwrap(),
        ],
    );
    let active = fixture.dir("active");
    init_jj(&active, false);
    fs::write(active.join("file"), "local\n").unwrap();
    jj(&active, &["describe", "-m", "local"]);
    jj(&active, &["new"]);
    jj(
        &active,
        &["git", "remote", "add", "origin", bare.to_str().unwrap()],
    );
    fs::write(active.join("unsnapshotted"), "keep disk\n").unwrap();
    let state = disk_state(&active);
    let mut repository = open(&active);
    let catalog = repository.list_remote("origin").unwrap();
    let remote = catalog
        .entries
        .iter()
        .find(|r| {
            r.target
                == (RevisionTarget::Remote {
                    remote: "origin".into(),
                    reference: "refs/heads/never-fetched".into(),
                })
        })
        .unwrap()
        .clone();
    assert!(
        !catalog
            .entries
            .iter()
            .any(|r| r.target == RevisionTarget::Commit(ancestor.clone()))
    );
    let local = catalog.entries.iter().find(|revision| {
        matches!(&revision.target, RevisionTarget::Commit(id) if id.bytes().any(|byte| byte != b'0'))
    }).unwrap();
    let branch = repository
        .compare(60, local, &remote, ComparisonMode::BranchChanges, &[])
        .unwrap();
    assert!(branch.before.ends_with(&"0".repeat(40)));
    assert_eq!(branch.files.len(), 1);
    assert_eq!(repository.load_file(60, 0).unwrap().after, ["remote tip"]);
    assert!(branch.editable_paths.is_empty());
    let comparison =
        compare_loaded(&mut repository, &remote, &working(RepoKind::Jujutsu), &[]).unwrap();
    assert_eq!(
        changed(&comparison, Path::new("file")).before,
        ["remote tip"]
    );
    assert_eq!(changed(&comparison, Path::new("file")).after, ["local"]);
    let loaded = repository.fetch_remote("origin").unwrap();
    let historic = loaded
        .entries
        .iter()
        .find(|r| {
            r.target == RevisionTarget::Commit(ancestor.clone())
                && r.category == Category::Revisions
        })
        .unwrap();
    let comparison = compare_loaded(&mut repository, historic, &remote, &[]).unwrap();
    assert_eq!(
        changed(&comparison, Path::new("file")).before,
        ["remote ancestor"]
    );
    assert_eq!(
        changed(&comparison, Path::new("file")).after,
        ["remote tip"]
    );
    let branch = repository
        .compare(61, historic, &remote, ComparisonMode::BranchChanges, &[])
        .unwrap();
    assert!(branch.before.ends_with(&ancestor));
    assert_eq!(
        repository.load_file(61, 0).unwrap().before,
        ["remote ancestor"]
    );
    let store = active.join(".jj/repo/store");
    let active_store =
        fs::canonicalize(store.join(fs::read_to_string(store.join("git_target")).unwrap().trim()))
            .unwrap();
    assert!(
        !command(
            "git",
            &active,
            &[
                "--git-dir",
                active_store.to_str().unwrap(),
                "cat-file",
                "-e",
                &tip
            ]
        )
        .status
        .success()
    );
    assert_eq!(disk_state(&active), state);
    assert!(
        repository
            .refresh_checkout(61, 62, false, &[])
            .unwrap()
            .is_none()
    );
    // Simulate importing and checking out the privately selected endpoint behind
    // the viewer. Its initially unavailable active-jj identity must be retried.
    jj(&active, &["git", "fetch", "--remote", "origin"]);
    jj(&active, &["edit", "--ignore-immutable", &tip]);
    let checked_out_state = disk_state(&active);
    let promoted = repository
        .refresh_checkout(
            61,
            62,
            false,
            &[(active.join("file"), "dirty live\n".into())],
        )
        .unwrap()
        .map(checkout_comparison)
        .unwrap();
    assert_eq!(promoted.before, branch.before);
    assert_eq!(promoted.after, branch.after);
    assert_eq!(promoted.blame, branch.blame);
    assert!(promoted.editable_paths.contains(Path::new("file")));
    assert_eq!(repository.load_file(62, 0).unwrap().after, ["remote tip"]);
    assert_eq!(disk_state(&active), checked_out_state);
}

#[test]
fn errors_are_explicit_and_do_not_modify_active_repository() {
    let fixture = Fixture::new();
    assert!(Repository::open(&fixture.0, Arc::new(AtomicBool::new(false))).is_err());
    let root = fixture.dir("active");
    init_git(&root);
    fs::write(root.join("file"), "baseline\n").unwrap();
    git(&root, &["add", "."]);
    git(&root, &["commit", "-m", "baseline"]);
    let id = git(&root, &["rev-parse", "HEAD"]);
    git(
        &root,
        &[
            "remote",
            "add",
            "broken",
            fixture.0.join("missing.git").to_str().unwrap(),
        ],
    );
    let state = disk_state(&root);
    let mut repository = open(&root);
    let catalog = repository.catalog().unwrap();
    assert!(catalog.notice.is_none());
    assert!(
        catalog
            .entries
            .iter()
            .any(|revision| revision.target == RevisionTarget::ListRemote("broken".into()))
    );
    assert!(repository.list_remote("broken").is_err());
    assert!(repository.fetch_remote("broken").is_err());
    assert!(
        repository
            .fetch_remote("unknown")
            .unwrap_err()
            .contains("Unknown configured remote")
    );
    assert!(
        repository
            .compare(
                1,
                &revision("--bad", RepoKind::Git),
                &working(RepoKind::Git),
                ComparisonMode::Snapshots,
                &[]
            )
            .unwrap_err()
            .contains("Invalid immutable commit")
    );
    assert!(
        repository
            .compare(
                1,
                &revision(&"f".repeat(40), RepoKind::Git),
                &working(RepoKind::Git),
                ComparisonMode::Snapshots,
                &[],
            )
            .unwrap_err()
            .contains("unavailable")
    );
    let loader = Revision {
        target: RevisionTarget::FetchRemote("broken".into()),
        ..working(RepoKind::Git)
    };
    assert!(
        repository
            .compare(
                1,
                &loader,
                &revision(&id, RepoKind::Git),
                ComparisonMode::Snapshots,
                &[]
            )
            .unwrap_err()
            .contains("history loader")
    );
    assert!(
        Repository::open(&root, Arc::new(AtomicBool::new(true)))
            .err()
            .unwrap()
            .contains("cancelled")
    );
    assert_eq!(disk_state(&root), state);
}

#[test]
fn unchanged_submodules_are_not_false_changes_and_changed_pointers_are_explicit() {
    let fixture = Fixture::new();
    let child = fixture.dir("child");
    init_git(&child);
    fs::write(child.join("file"), "first\n").unwrap();
    git(&child, &["add", "."]);
    git(&child, &["commit", "-m", "first"]);
    let first = git(&child, &["rev-parse", "HEAD"]);
    let root = fixture.dir("active");
    init_git(&root);
    git(
        &root,
        &[
            "-c",
            "protocol.file.allow=always",
            "submodule",
            "add",
            child.to_str().unwrap(),
            "nested",
        ],
    );
    git(&root, &["commit", "-m", "submodule"]);
    let baseline = git(&root, &["rev-parse", "HEAD"]);
    let mut repository = open(&root);
    assert!(
        repository
            .compare(
                1,
                &revision(&baseline, RepoKind::Git),
                &working(RepoKind::Git),
                ComparisonMode::Snapshots,
                &[]
            )
            .unwrap()
            .files
            .is_empty()
    );
    fs::write(child.join("file"), "second\n").unwrap();
    git(&child, &["commit", "-am", "second"]);
    let second = git(&child, &["rev-parse", "HEAD"]);
    git(&root.join("nested"), &["fetch", "origin"]);
    git(&root.join("nested"), &["checkout", "--detach", &second]);
    let state = disk_state(&root);
    let comparison = compare_loaded(
        &mut repository,
        &revision(&baseline, RepoKind::Git),
        &working(RepoKind::Git),
        &[],
    )
    .unwrap();
    let submodule = changed(&comparison, Path::new("nested"));
    assert_eq!(submodule.status, FileStatus::Modified);
    let notice = submodule.notice.as_ref().unwrap();
    assert!(
        notice.contains(&first) && notice.contains(&second) && notice.contains("not traversed")
    );
    assert!(submodule.before.is_empty() && submodule.after.is_empty());
    assert!(
        !comparison
            .files
            .iter()
            .any(|f| f.path.starts_with("nested/file"))
    );
    assert_eq!(disk_state(&root), state);
}

#[test]
fn multiple_remotes_retain_tag_only_history_even_when_tag_names_collide() {
    let fixture = Fixture::new();
    let mut ids = vec![];
    let mut urls = vec![];
    for name in ["one", "two"] {
        let source = fixture.dir(name);
        init_git(&source);
        fs::write(source.join("file"), format!("{name}\n")).unwrap();
        git(&source, &["add", "."]);
        git(
            &source,
            &["commit", "-m", &format!("{name} tag-only needle")],
        );
        ids.push(git(&source, &["rev-parse", "HEAD"]));
        git(&source, &["tag", "collision"]);
        git(&source, &["update-ref", "-d", "refs/heads/local"]);
        let bare = fixture.0.join(format!("{name}.git"));
        git(
            &fixture.0,
            &[
                "clone",
                "--bare",
                source.to_str().unwrap(),
                bare.to_str().unwrap(),
            ],
        );
        urls.push(bare);
    }
    let active = fixture.dir("active");
    init_git(&active);
    fs::write(active.join("local"), "local\n").unwrap();
    git(&active, &["add", "."]);
    git(&active, &["commit", "-m", "local"]);
    for (name, url) in ["one", "two"].into_iter().zip(&urls) {
        git(&active, &["remote", "add", name, url.to_str().unwrap()]);
    }
    let state = disk_state(&active);
    let mut repository = open(&active);
    repository.fetch_remote("one").unwrap();
    let loaded = repository.fetch_remote("two").unwrap();
    for (name, id) in ["one", "two"].into_iter().zip(&ids) {
        assert!(
            loaded
                .entries
                .iter()
                .any(|r| r.target == RevisionTarget::Commit(id.clone())
                    && r.description == format!("{name} tag-only needle"))
        );
    }
    let comparison = compare_loaded(
        &mut repository,
        &revision(&ids[0], RepoKind::Git),
        &revision(&ids[1], RepoKind::Git),
        &[],
    )
    .unwrap();
    assert_eq!(changed(&comparison, Path::new("file")).before, ["one"]);
    assert_eq!(changed(&comparison, Path::new("file")).after, ["two"]);
    assert_eq!(disk_state(&active), state);
}

#[test]
fn jj_conflicted_revisions_show_cli_projection_and_keep_ordinary_files_navigable() {
    let fixture = Fixture::new();
    let root = fixture.dir("active");
    init_jj(&root, false);
    fs::write(root.join("conflict"), "base\n").unwrap();
    fs::write(root.join("ordinary"), "old\n").unwrap();
    symlink("ordinary", root.join("unchanged-link")).unwrap();
    jj(&root, &["describe", "-m", "base"]);
    let base = jj(
        &root,
        &[
            "--ignore-working-copy",
            "log",
            "--no-graph",
            "-r",
            "@",
            "-T",
            "commit_id",
        ],
    );
    jj(&root, &["new", &base]);
    fs::write(root.join("conflict"), "left\n").unwrap();
    fs::write(root.join("ordinary"), "left ordinary\n").unwrap();
    jj(&root, &["describe", "-m", "left"]);
    let left = jj(
        &root,
        &[
            "--ignore-working-copy",
            "log",
            "--no-graph",
            "-r",
            "@",
            "-T",
            "commit_id",
        ],
    );
    jj(&root, &["new", &base]);
    fs::write(root.join("conflict"), "right\n").unwrap();
    jj(&root, &["describe", "-m", "right"]);
    let right = jj(
        &root,
        &[
            "--ignore-working-copy",
            "log",
            "--no-graph",
            "-r",
            "@",
            "-T",
            "commit_id",
        ],
    );
    jj(&root, &["new", &left, &right, "-m", "conflicted merge"]);
    let merged = jj(
        &root,
        &[
            "--ignore-working-copy",
            "--at-operation=@",
            "log",
            "--no-graph",
            "-r",
            "@",
            "-T",
            "commit_id",
        ],
    );
    let projection = command(
        "jj",
        &root,
        &[
            "--ignore-working-copy",
            "--at-operation=@",
            "file",
            "show",
            "-r",
            &merged,
            "-T",
            "",
            "--",
            "root-file:\"conflict\"",
        ],
    );
    assert!(
        projection.status.success(),
        "{}",
        String::from_utf8_lossy(&projection.stderr)
    );
    let projection = String::from_utf8(projection.stdout).unwrap();
    let expected: Vec<_> = projection
        .strip_suffix('\n')
        .unwrap_or(&projection)
        .split('\n')
        .map(str::to_owned)
        .collect();
    let state = disk_state(&root);
    let mut repository = open(&root);
    let catalog = repository.catalog().unwrap();
    assert!(
        catalog
            .entries
            .iter()
            .any(|r| r.target == RevisionTarget::Commit(merged.clone()))
    );
    let comparison = compare_loaded(
        &mut repository,
        &revision(&base, RepoKind::Jujutsu),
        &revision(&merged, RepoKind::Jujutsu),
        &[],
    )
    .unwrap();
    assert_eq!(
        comparison
            .files
            .iter()
            .map(|file| file.path.as_path())
            .collect::<Vec<_>>(),
        [Path::new("conflict"), Path::new("ordinary")]
    );
    let conflict = changed(&comparison, Path::new("conflict"));
    assert_eq!(conflict.after, expected);
    assert!(
        conflict
            .notice
            .as_ref()
            .unwrap()
            .contains("conflict projection")
    );
    assert!(!conflict.hunks.is_empty());
    let ordinary = changed(&comparison, Path::new("ordinary"));
    assert_eq!(ordinary.before, ["old"]);
    assert_eq!(ordinary.after, ["left ordinary"]);
    assert!(ordinary.notice.is_none());
    let branch = repository
        .compare(
            30,
            &revision(&base, RepoKind::Jujutsu),
            &revision(&merged, RepoKind::Jujutsu),
            ComparisonMode::BranchChanges,
            &[],
        )
        .unwrap();
    assert_eq!(changed(&branch, Path::new("conflict")).stats, None);
    assert_eq!(changed(&branch, Path::new("ordinary")).stats, Some((1, 1)));
    let index = branch
        .files
        .iter()
        .position(|file| file.path == Path::new("conflict"))
        .unwrap();
    let conflict = repository.load_file(30, index).unwrap();
    assert_eq!(conflict.after, expected);
    assert!(
        conflict
            .notice
            .as_deref()
            .unwrap()
            .contains("conflict projection")
    );
    let working_comparison = compare_loaded(
        &mut repository,
        &revision(&merged, RepoKind::Jujutsu),
        &working(RepoKind::Jujutsu),
        &[],
    )
    .unwrap();
    assert!(
        changed(&working_comparison, Path::new("conflict"))
            .notice
            .as_ref()
            .unwrap()
            .contains("conflict projection")
    );
    assert_eq!(disk_state(&root), state);
}

#[test]
fn conflicted_catalog_preserves_symlinks_and_defers_unselected_contents() {
    let fixture = Fixture::new();
    let root = fixture.dir("lazy-conflict");
    init_jj(&root, false);
    jj(
        &root,
        &[
            "config",
            "set",
            "--repo",
            "snapshot.max-new-file-size",
            "100MiB",
        ],
    );
    let tail_line = "x".repeat(1023);
    let tail = format!("{tail_line}\n").repeat(17 * 1024 + 1);
    fs::write(root.join("conflict"), format!("base\n{tail}")).unwrap();
    fs::write(root.join("unselected"), "old\n").unwrap();
    symlink("unselected", root.join("unchanged-link")).unwrap();
    jj(&root, &["describe", "-m", "base"]);
    let base = jj(&root, &["log", "--no-graph", "-r", "@", "-T", "commit_id"]);
    jj(&root, &["new", &base]);
    fs::write(root.join("conflict"), format!("left\n{tail}")).unwrap();
    fs::write(root.join("unselected"), vec![b'x'; 17 * 1024 * 1024]).unwrap();
    jj(&root, &["describe", "-m", "left"]);
    let left = jj(&root, &["log", "--no-graph", "-r", "@", "-T", "commit_id"]);
    jj(&root, &["new", &base]);
    fs::write(root.join("conflict"), format!("right\n{tail}")).unwrap();
    jj(&root, &["describe", "-m", "right"]);
    let right = jj(&root, &["log", "--no-graph", "-r", "@", "-T", "commit_id"]);
    jj(&root, &["new", &left, &right, "-m", "conflicted merge"]);
    let merged = jj(&root, &["log", "--no-graph", "-r", "@", "-T", "commit_id"]);
    let state = disk_state(&root);
    let mut repository = open(&root);
    let comparison = repository
        .compare(
            1,
            &revision(&base, RepoKind::Jujutsu),
            &revision(&merged, RepoKind::Jujutsu),
            ComparisonMode::BranchChanges,
            &[],
        )
        .unwrap();
    assert_eq!(
        comparison
            .files
            .iter()
            .map(|file| file.path.as_path())
            .collect::<Vec<_>>(),
        [Path::new("conflict"), Path::new("unselected")]
    );
    let conflict = repository.load_file(1, 0).unwrap();
    assert_eq!(conflict.before[0], "base");
    assert_eq!(conflict.before.len(), 17 * 1024 + 2);
    assert!(conflict.before[1..].iter().all(|line| line == &tail_line));
    let projection = jj(
        &root,
        &[
            "--ignore-working-copy",
            "file",
            "show",
            "-r",
            &merged,
            "-T",
            "",
            "--",
            "conflict",
        ],
    );
    assert!(projection.len() > 16 * 1024 * 1024);
    assert_eq!(conflict.after, projection.lines().collect::<Vec<_>>());
    assert!(!conflict.hunks.is_empty());
    let large = repository.load_file(1, 1).unwrap();
    assert_eq!(large.after.len(), 1);
    assert_eq!(large.after[0].len(), 17 * 1024 * 1024);
    assert!(large.after[0].bytes().all(|byte| byte == b'x'));
    assert_eq!(disk_state(&root), state);

    jj(&root, &["new", &merged]);
    fs::write(root.join("extra"), "extra\n").unwrap();
    jj(
        &root,
        &["describe", "-m", "unrelated change retaining conflict"],
    );
    let next = jj(&root, &["log", "--no-graph", "-r", "@", "-T", "commit_id"]);
    let comparison = repository
        .compare(
            2,
            &revision(&merged, RepoKind::Jujutsu),
            &revision(&next, RepoKind::Jujutsu),
            ComparisonMode::Snapshots,
            &[],
        )
        .unwrap();
    assert_eq!(
        comparison
            .files
            .iter()
            .map(|file| file.path.as_path())
            .collect::<Vec<_>>(),
        [Path::new("extra")]
    );
}

#[test]
fn unsaved_overlays_are_working_after_only_and_cannot_follow_nonregular_paths() {
    let fixture = Fixture::new();
    let root = fs::canonicalize(fixture.dir("overlay")).unwrap();
    init_git(&root);
    fs::create_dir(root.join("sub")).unwrap();
    fs::write(root.join("file"), "base\n").unwrap();
    fs::write(root.join("sub/file"), "nested\n").unwrap();
    fs::write(root.join("binary"), b"\0binary").unwrap();
    git(&root, &["add", "."]);
    git(&root, &["commit", "-m", "base"]);
    let id = git(&root, &["rev-parse", "HEAD"]);
    let outside = fixture.dir("outside");
    fs::write(outside.join("file"), "outside\n").unwrap();
    symlink(&outside, root.join("linked")).unwrap();
    symlink("file", root.join("link")).unwrap();
    let state = disk_state(&root);
    let buffers = vec![
        (root.join("file"), "unsaved\n".into()),
        (root.join("binary"), "not binary\n".into()),
        (root.join("missing"), "not on disk\n".into()),
        (root.join("link"), "not a regular file\n".into()),
        (root.join("linked/file"), "outside via link\n".into()),
        (outside.join("file"), "outside\n".into()),
        (root.join("sub/../../outside/file"), "escaped\n".into()),
        (root.join(".git/config"), "metadata\n".into()),
    ];
    let mut repository = open(&root.join("sub"));
    let base = revision(&id, RepoKind::Git);
    let checkout = working(RepoKind::Git);
    let comparison = compare_loaded(&mut repository, &base, &checkout, &buffers).unwrap();
    assert_eq!(comparison.root, fs::canonicalize(&root).unwrap());
    assert_eq!(changed(&comparison, Path::new("file")).after, ["unsaved"]);
    assert!(comparison.editable_paths.contains(Path::new("file")));
    for path in [
        "binary",
        "missing",
        "link",
        "linked",
        "linked/file",
        ".git/config",
    ] {
        assert!(!comparison.editable_paths.contains(Path::new(path)));
    }
    assert!(
        !comparison
            .files
            .iter()
            .any(|file| file.path == Path::new("binary")
                || file.path == Path::new("missing")
                || file.path == Path::new("linked/file"))
    );
    let immutable = compare_loaded(&mut repository, &checkout, &base, &buffers).unwrap();
    assert!(immutable.editable_paths.is_empty());
    assert!(
        !immutable
            .files
            .iter()
            .any(|file| file.path == Path::new("file"))
    );
    assert!(
        repository
            .compare(1, &base, &base, ComparisonMode::Snapshots, &buffers)
            .unwrap()
            .files
            .is_empty()
    );
    let same_checkout = compare_loaded(&mut repository, &checkout, &checkout, &buffers).unwrap();
    assert_eq!(changed(&same_checkout, Path::new("file")).before, ["base"]);
    assert_eq!(
        changed(&same_checkout, Path::new("file")).after,
        ["unsaved"]
    );
    assert_eq!(disk_state(&root), state);
    assert_eq!(
        fs::read_to_string(outside.join("file")).unwrap(),
        "outside\n"
    );
}

#[test]
fn immutable_catalog_skips_unchanged_blobs_and_prepares_only_requested_details() {
    let fixture = Fixture::new();
    let root = fixture.dir("lazy");
    init_git(&root);
    fs::write(root.join("unchanged-large"), vec![b'x'; 17 * 1024 * 1024]).unwrap();
    fs::write(root.join("selected"), "before\n").unwrap();
    fs::write(root.join("unselected"), "old\n").unwrap();
    git(&root, &["add", "."]);
    git(&root, &["commit", "-m", "before"]);
    let before = git(&root, &["rev-parse", "HEAD"]);
    fs::write(root.join("selected"), "after\n").unwrap();
    fs::write(root.join("unselected"), vec![b'y'; 17 * 1024 * 1024]).unwrap();
    git(&root, &["add", "."]);
    git(&root, &["commit", "-m", "after"]);
    let after = git(&root, &["rev-parse", "HEAD"]);
    let mut repository = open(&root);
    let comparison = repository
        .compare(
            100,
            &revision(&before, RepoKind::Git),
            &revision(&after, RepoKind::Git),
            ComparisonMode::Snapshots,
            &[],
        )
        .unwrap();
    assert_eq!(comparison.files.len(), 2);
    assert!(comparison.files.iter().all(|file| !file.loaded
        && file.before.is_empty()
        && file.after.is_empty()
        && file.hunks.is_empty()));
    let index = comparison
        .files
        .iter()
        .position(|file| file.path == Path::new("selected"))
        .unwrap();
    let selected = repository.load_file(100, index).unwrap();
    assert!(selected.loaded);
    assert_eq!(selected.before, ["before"]);
    assert_eq!(selected.after, ["after"]);
    assert_eq!(selected.hunks.len(), 1);
    assert!(repository.load_file(99, index).is_err());
    let empty = repository
        .compare(
            101,
            &revision(&after, RepoKind::Git),
            &revision(&after, RepoKind::Git),
            ComparisonMode::Snapshots,
            &[],
        )
        .unwrap();
    assert!(empty.files.is_empty());
    assert!(repository.load_file(100, index).is_err());
}

#[test]
fn comparison_size_and_line_ceilings_are_lazy_and_explicit() {
    let fixture = Fixture::new();
    let root = fixture.dir("ceilings");
    init_git(&root);
    git(&root, &["commit", "--allow-empty", "-m", "before"]);
    let before = revision(&git(&root, &["rev-parse", "HEAD"]), RepoKind::Git);
    fs::File::create(root.join("too-many-bytes"))
        .unwrap()
        .set_len(64 * 1024 * 1024 + 1)
        .unwrap();
    fs::write(root.join("too-many-lines"), vec![b'\n'; 4_000_001]).unwrap();
    fs::write(root.join("selected"), "still available\n").unwrap();
    git(&root, &["add", "."]);
    git(&root, &["commit", "-m", "after"]);
    let after = revision(&git(&root, &["rev-parse", "HEAD"]), RepoKind::Git);
    let mut repository = open(&root);
    let catalog = repository
        .compare(1, &before, &after, ComparisonMode::Snapshots, &[])
        .unwrap();
    assert_eq!(catalog.files.len(), 3);
    assert!(catalog.files.iter().all(|file| !file.loaded));
    assert_eq!(changed(&catalog, Path::new("too-many-bytes")).stats, None);
    assert_eq!(changed(&catalog, Path::new("selected")).stats, Some((1, 0)));
    for (index, entry) in catalog.files.iter().enumerate() {
        match entry.path.to_str().unwrap() {
            "selected" => assert_eq!(
                repository.load_file(1, index).unwrap().after,
                ["still available"]
            ),
            "too-many-bytes" => assert!(
                repository
                    .load_file(1, index)
                    .unwrap_err()
                    .contains("64 MiB per-side comparison file limit")
            ),
            "too-many-lines" => assert!(
                repository
                    .load_file(1, index)
                    .unwrap_err()
                    .contains("4000000-line per-side comparison limit")
            ),
            path => panic!("Unexpected file {path}"),
        }
    }
}

#[test]
fn large_git_and_jj_comparisons_load_exact_snapshots_and_frozen_working_overlays() {
    let fixture = Fixture::new();
    // Both modified sides exceed 52.3 MB; the Working pair exceeds the old
    // aggregate 64 MiB budget as well as its old 16 MiB per-file limit.
    let body_line = "x".repeat(1023);
    let mut contents = format!(
        "before\n{}",
        format!("{body_line}\n").repeat(52_300_000 / 1024 + 1)
    );
    let line_count = contents.lines().count();
    for kind in [RepoKind::Git, RepoKind::Jujutsu] {
        let root = fixture
            .dir(if kind == RepoKind::Git { "git" } else { "jj" })
            .canonicalize()
            .unwrap();
        match kind {
            RepoKind::Git => init_git(&root),
            RepoKind::Jujutsu => {
                init_jj(&root, false);
                jj(
                    &root,
                    &[
                        "config",
                        "set",
                        "--repo",
                        "snapshot.max-new-file-size",
                        "100MiB",
                    ],
                );
            }
        }
        let set_header = |contents: &mut String, header: &str| {
            let end = contents.find('\n').unwrap();
            contents.replace_range(..end, header);
        };
        set_header(&mut contents, "before");
        fs::write(root.join("modified"), &contents).unwrap();
        set_header(&mut contents, "removed");
        fs::write(root.join("removed"), &contents).unwrap();
        let before = match kind {
            RepoKind::Git => {
                git(&root, &["add", "."]);
                git(&root, &["commit", "-m", "large before"]);
                git(&root, &["rev-parse", "HEAD"])
            }
            RepoKind::Jujutsu => {
                jj(&root, &["describe", "-m", "large before"]);
                let id = jj(&root, &["log", "--no-graph", "-r", "@", "-T", "commit_id"]);
                jj(&root, &["new", &id]);
                id
            }
        };
        set_header(&mut contents, "after");
        fs::write(root.join("modified"), &contents).unwrap();
        fs::remove_file(root.join("removed")).unwrap();
        set_header(&mut contents, "added");
        fs::write(root.join("added"), &contents).unwrap();
        let after = match kind {
            RepoKind::Git => {
                git(&root, &["add", "."]);
                git(&root, &["commit", "-m", "large after"]);
                git(&root, &["rev-parse", "HEAD"])
            }
            RepoKind::Jujutsu => {
                jj(&root, &["describe", "-m", "large after"]);
                jj(&root, &["log", "--no-graph", "-r", "@", "-T", "commit_id"])
            }
        };
        let assert_contents = |lines: &[String], header: &str| {
            assert_eq!(lines.len(), line_count);
            assert_eq!(lines[0], header);
            assert!(lines[1..].iter().all(|line| line == &body_line));
        };
        let cancelled = Arc::new(AtomicBool::new(false));
        let mut repository = Repository::open(&root, cancelled.clone()).unwrap();
        let catalog = repository
            .compare(
                1,
                &revision(&before, kind),
                &revision(&after, kind),
                ComparisonMode::Snapshots,
                &[],
            )
            .unwrap();
        assert_eq!(catalog.files.len(), 3);
        assert!(catalog.files.iter().all(|file| !file.loaded
            && file.before.is_empty()
            && file.after.is_empty()
            && file.hunks.is_empty()));
        for (index, entry) in catalog.files.iter().enumerate() {
            let file = repository.load_file(1, index).unwrap();
            assert!(file.loaded);
            assert_eq!(file.hunks.len(), 1);
            let hunk = &file.hunks[0];
            let expected = match entry.path.to_str().unwrap() {
                "added" => {
                    assert_eq!(file.status, FileStatus::Added);
                    assert!(file.before.is_empty());
                    assert_contents(&file.after, "added");
                    (0, 0, 0, line_count)
                }
                "removed" => {
                    assert_eq!(file.status, FileStatus::Removed);
                    assert_contents(&file.before, "removed");
                    assert!(file.after.is_empty());
                    (0, line_count, 0, 0)
                }
                "modified" => {
                    assert_eq!(file.status, FileStatus::Modified);
                    assert_contents(&file.before, "before");
                    assert_contents(&file.after, "after");
                    (0, 1, 0, 1)
                }
                path => panic!("Unexpected file {path}"),
            };
            assert_eq!(
                (
                    hunk.before_start,
                    hunk.before_len,
                    hunk.after_start,
                    hunk.after_len
                ),
                expected
            );
            assert!(file.before.is_empty() || file.before_eof);
            assert!(file.after.is_empty() || file.after_eof);
        }
        set_header(&mut contents, "overlay");
        let buffers = [(root.join("modified"), contents)];
        let working = repository
            .compare(
                2,
                &revision(&after, kind),
                &working(kind),
                ComparisonMode::Snapshots,
                &buffers,
            )
            .unwrap();
        assert_eq!(working.files.len(), 1);
        assert!(!working.files[0].loaded);
        assert!(working.editable_paths.contains(Path::new("modified")));
        fs::write(root.join("modified"), "later disk contents\n").unwrap();
        cancelled.store(true, Ordering::Release);
        assert!(
            repository
                .load_file(2, 0)
                .unwrap_err()
                .contains("cancelled")
        );
        cancelled.store(false, Ordering::Release);
        let file = repository.load_file(2, 0).unwrap();
        assert_contents(&file.before, "after");
        assert_contents(&file.after, "overlay");
        assert_eq!(file.hunks.len(), 1);
        let hunk = &file.hunks[0];
        assert_eq!(
            (
                hunk.before_start,
                hunk.before_len,
                hunk.after_start,
                hunk.after_len
            ),
            (0, 1, 0, 1)
        );
        contents = buffers.into_iter().next().unwrap().1;
    }
}

#[test]
fn deferred_file_details_keep_frozen_checkout_and_unsaved_after() {
    let fixture = Fixture::new();
    let root = fixture.dir("frozen").canonicalize().unwrap();
    init_git(&root);
    fs::write(root.join("file"), "committed\n").unwrap();
    git(&root, &["add", "."]);
    git(&root, &["commit", "-m", "before"]);
    fs::write(root.join("file"), "disk before\n").unwrap();
    let mut repository = open(&root);
    let comparison = repository
        .compare(
            50,
            &working(RepoKind::Git),
            &working(RepoKind::Git),
            ComparisonMode::Snapshots,
            &[(root.join("file"), "unsaved after\n".into())],
        )
        .unwrap();
    assert_eq!(comparison.files.len(), 1);
    assert!(!comparison.files[0].loaded);
    fs::write(root.join("file"), "later disk\n").unwrap();
    let details = repository.load_file(50, 0).unwrap();
    assert_eq!(details.before, ["disk before"]);
    assert_eq!(details.after, ["unsaved after"]);
    let again = repository.load_file(50, 0).unwrap();
    assert_eq!(again.before, details.before);
    assert_eq!(again.after, details.after);
}

#[test]
fn git_working_after_advances_only_to_descendants_with_new_paths_and_unsaved_text() {
    let fixture = Fixture::new();
    let root = fixture.dir("follow").canonicalize().unwrap();
    init_git(&root);
    fs::write(root.join("file"), "base\n").unwrap();
    fs::write(root.join("removed"), "remove me\n").unwrap();
    git(&root, &["add", "."]);
    git(&root, &["commit", "-m", "base"]);
    let base = git(&root, &["rev-parse", "HEAD"]);
    fs::write(root.join("file"), "original disk\n").unwrap();
    let mut repository = open(&root);
    let original = compare_loaded(
        &mut repository,
        &revision(&base, RepoKind::Git),
        &working(RepoKind::Git),
        &[],
    )
    .unwrap();
    fs::write(root.join("file"), "later disk\n").unwrap();
    assert!(
        repository
            .refresh_checkout(1, 2, true, &[])
            .unwrap()
            .is_none()
    );
    assert_eq!(repository.load_file(1, 0).unwrap().after, ["original disk"]);
    fs::remove_file(root.join("removed")).unwrap();
    fs::write(root.join("added"), "new file\n").unwrap();
    git(&root, &["add", "."]);
    git(&root, &["commit", "-m", "descendant"]);
    let tip = git(&root, &["rev-parse", "HEAD"]);
    let state = disk_state(&root);
    assert!(
        repository
            .refresh_checkout(99, 2, true, &[])
            .unwrap()
            .is_none()
    );
    assert!(
        repository
            .refresh_checkout(1, 2, false, &[])
            .unwrap()
            .is_none()
    );
    assert_eq!(repository.load_file(1, 0).unwrap().after, ["original disk"]);
    let mut refreshed = repository
        .refresh_checkout(1, 2, true, &[(root.join("file"), "unsaved\n".into())])
        .unwrap()
        .map(checkout_comparison)
        .unwrap();
    assert_eq!(refreshed.before, original.before);
    assert_eq!(refreshed.after, original.after);
    assert_eq!(refreshed.blame[0], original.blame[0]);
    assert_eq!(refreshed.blame[1].as_ref().unwrap().commit, tip);
    for (index, file) in refreshed.files.iter_mut().enumerate() {
        *file = repository.load_file(2, index).unwrap();
    }
    assert_eq!(changed(&refreshed, Path::new("file")).before, ["base"]);
    assert_eq!(changed(&refreshed, Path::new("file")).after, ["unsaved"]);
    assert_eq!(
        changed(&refreshed, Path::new("added")).status,
        FileStatus::Added
    );
    assert_eq!(
        changed(&refreshed, Path::new("removed")).status,
        FileStatus::Removed
    );
    assert!(refreshed.editable_paths.contains(Path::new("file")));
    assert!(refreshed.editable_paths.contains(Path::new("added")));
    assert!(!refreshed.editable_paths.contains(Path::new("removed")));
    assert!(repository.load_file(1, 0).is_err());
    assert!(
        repository
            .refresh_checkout(2, 3, true, &[])
            .unwrap()
            .is_none()
    );
    assert_eq!(disk_state(&root), state);
    git(&root, &["checkout", "--detach", &base]);
    assert!(
        repository
            .refresh_checkout(2, 3, true, &[])
            .unwrap()
            .is_none()
    );
    git(&root, &["checkout", "-b", "other"]);
    fs::write(root.join("file"), "other branch\n").unwrap();
    git(&root, &["add", "."]);
    git(&root, &["commit", "-m", "unrelated to tip"]);
    assert!(
        repository
            .refresh_checkout(2, 3, true, &[])
            .unwrap()
            .is_none()
    );
    let index = refreshed
        .files
        .iter()
        .position(|file| file.path == Path::new("file"))
        .unwrap();
    assert_eq!(repository.load_file(2, index).unwrap().after, ["unsaved"]);
    git(&root, &["checkout", "--detach", &tip]);
    assert!(
        repository
            .refresh_checkout(2, 3, true, &[])
            .unwrap()
            .is_none()
    );
}

#[test]
fn working_after_refresh_preserves_frozen_working_before_and_sources_on_failure() {
    let fixture = Fixture::new();
    let root = fixture.dir("frozen-follow").canonicalize().unwrap();
    init_git(&root);
    fs::write(root.join("file"), "base\n").unwrap();
    git(&root, &["add", "."]);
    git(&root, &["commit", "-m", "base"]);
    let base = revision(&git(&root, &["rev-parse", "HEAD"]), RepoKind::Git);
    fs::write(root.join("file"), "frozen before\n").unwrap();
    let cancelled = Arc::new(AtomicBool::new(false));
    let mut repository = Repository::open(&root, cancelled.clone()).unwrap();
    repository
        .compare(
            10,
            &working(RepoKind::Git),
            &working(RepoKind::Git),
            ComparisonMode::Snapshots,
            &[(root.join("file"), "frozen after\n".into())],
        )
        .unwrap();
    fs::write(root.join("file"), "next checkout\n").unwrap();
    git(&root, &["add", "."]);
    git(&root, &["commit", "-m", "next"]);
    cancelled.store(true, Ordering::Release);
    assert!(repository.refresh_checkout(10, 11, true, &[]).is_err());
    cancelled.store(false, Ordering::Release);
    assert_eq!(repository.load_file(10, 0).unwrap().after, ["frozen after"]);
    fs::File::create(root.join("oversized"))
        .unwrap()
        .set_len(64 * 1024 * 1024 + 1)
        .unwrap();
    assert!(
        repository
            .refresh_checkout(10, 11, true, &[])
            .unwrap_err()
            .contains("64 MiB per-side comparison file limit")
    );
    let original = repository.load_file(10, 0).unwrap();
    assert_eq!(original.before, ["frozen before"]);
    assert_eq!(original.after, ["frozen after"]);
    assert!(repository.load_file(11, 0).is_err());
    fs::remove_file(root.join("oversized")).unwrap();
    let refreshed = repository
        .refresh_checkout(10, 11, true, &[])
        .unwrap()
        .map(checkout_comparison)
        .unwrap();
    assert_eq!(refreshed.files.len(), 1);
    let file = repository.load_file(11, 0).unwrap();
    assert_eq!(file.before, ["frozen before"]);
    assert_eq!(file.after, ["next checkout"]);
    let tip = revision(&git(&root, &["rev-parse", "HEAD"]), RepoKind::Git);
    let pinned = repository
        .compare(12, &base, &tip, ComparisonMode::Snapshots, &[])
        .unwrap();
    assert!(pinned.editable_paths.contains(Path::new("file")));
    fs::write(root.join("file"), "newer checkout\n").unwrap();
    git(&root, &["add", "."]);
    git(&root, &["commit", "-m", "newer"]);
    assert!(
        repository
            .refresh_checkout(99, 13, false, &[])
            .unwrap()
            .is_none()
    );
    let readonly = repository
        .refresh_checkout(12, 13, false, &[(root.join("file"), "dirty live\n".into())])
        .unwrap()
        .map(checkout_comparison)
        .unwrap();
    assert_eq!(readonly.before, pinned.before);
    assert_eq!(readonly.after, pinned.after);
    assert!(readonly.editable_paths.is_empty());
    assert_eq!(readonly.files.len(), pinned.files.len());
    assert_eq!(readonly.files[0].path, pinned.files[0].path);
    assert!(repository.load_file(12, 0).is_err());
    assert_eq!(
        repository.load_file(13, 0).unwrap().after,
        ["next checkout"]
    );
    assert!(
        repository
            .refresh_checkout(13, 14, false, &[])
            .unwrap()
            .is_none()
    );
    let RevisionTarget::Commit(tip_id) = &tip.target else {
        unreachable!()
    };
    git(&root, &["checkout", "--detach", tip_id]);
    let promoted = repository
        .refresh_checkout(13, 14, false, &[])
        .unwrap()
        .map(checkout_comparison)
        .unwrap();
    assert_eq!(promoted.editable_paths, pinned.editable_paths);
    fs::write(root.join("file"), "dirty disk\n").unwrap();
    assert_eq!(
        repository.load_file(14, 0).unwrap().after,
        ["next checkout"]
    );
    cancelled.store(true, Ordering::Release);
    assert!(repository.refresh_checkout(14, 15, false, &[]).is_err());
    cancelled.store(false, Ordering::Release);
    let recovered = repository
        .refresh_checkout(14, 15, false, &[])
        .unwrap()
        .map(checkout_comparison)
        .unwrap();
    assert_eq!(recovered.editable_paths, pinned.editable_paths);
    assert_eq!(
        repository.load_file(15, 0).unwrap().after,
        ["next checkout"]
    );
}

#[test]
fn refresh_keeps_historical_blob_sources_lazy_even_with_working_files() {
    let fixture = Fixture::new();
    let root = fixture.dir("failed-materialization");
    init_git(&root);
    fs::write(root.join("a-file"), "frozen source\n").unwrap();
    fs::write(root.join("z-large"), vec![b'x'; 17 * 1024 * 1024]).unwrap();
    git(&root, &["add", "."]);
    git(&root, &["commit", "-m", "base"]);
    let base = revision(&git(&root, &["rev-parse", "HEAD"]), RepoKind::Git);
    fs::remove_file(root.join("a-file")).unwrap();
    fs::remove_file(root.join("z-large")).unwrap();
    let mut repository = open(&root);
    repository
        .compare(
            1,
            &base,
            &working(RepoKind::Git),
            ComparisonMode::Snapshots,
            &[],
        )
        .unwrap();
    assert_eq!(
        repository.load_file(1, 0).unwrap().before,
        ["frozen source"]
    );
    fs::write(root.join("a-file"), "new checkout\n").unwrap();
    git(&root, &["add", "."]);
    git(&root, &["commit", "-m", "descendant"]);
    let refreshed = repository
        .refresh_checkout(1, 2, true, &[])
        .unwrap()
        .map(checkout_comparison)
        .unwrap();
    assert!(refreshed.files.iter().all(|file| !file.loaded));
    let index = refreshed
        .files
        .iter()
        .position(|file| file.path == Path::new("a-file"))
        .unwrap();
    let file = repository.load_file(2, index).unwrap();
    assert_eq!(file.before, ["frozen source"]);
    assert_eq!(file.after, ["new checkout"]);
    assert_eq!(file.status, FileStatus::Modified);
    assert!(repository.load_file(1, index).is_err());
}

#[test]
fn unborn_git_working_after_safely_advances_to_its_first_commit() {
    let fixture = Fixture::new();
    let root = fixture.dir("unborn");
    init_git(&root);
    let mut repository = open(&root);
    repository
        .compare(
            1,
            &working(RepoKind::Git),
            &working(RepoKind::Git),
            ComparisonMode::Snapshots,
            &[],
        )
        .unwrap();
    assert!(
        repository
            .refresh_checkout(1, 2, true, &[])
            .unwrap()
            .is_none()
    );
    fs::write(root.join("first"), "initial\n").unwrap();
    git(&root, &["add", "."]);
    git(&root, &["commit", "-m", "initial"]);
    let comparison = repository
        .refresh_checkout(1, 2, true, &[])
        .unwrap()
        .map(checkout_comparison)
        .unwrap();
    assert_eq!(comparison.files.len(), 1);
    assert_eq!(repository.load_file(2, 0).unwrap().after, ["initial"]);
}

#[test]
fn jj_working_after_follows_changes_not_rewrites_and_rejects_other_history() {
    for colocate in [false, true] {
        let fixture = Fixture::new();
        let root = fixture.dir("jj-follow").canonicalize().unwrap();
        init_jj(&root, colocate);
        fs::write(root.join("file"), "base\n").unwrap();
        fs::write(root.join("removed"), "remove me\n").unwrap();
        jj(&root, &["describe", "-m", "base"]);
        let base = jj(&root, &["log", "--no-graph", "-r", "@", "-T", "commit_id"]);
        jj(&root, &["new"]);
        fs::write(root.join("file"), "original disk\n").unwrap();
        let mut repository = open(&root);
        let initial = compare_loaded(
            &mut repository,
            &revision(&base, RepoKind::Jujutsu),
            &working(RepoKind::Jujutsu),
            &[],
        )
        .unwrap();
        assert_eq!(initial.blame[1].as_ref().unwrap().commit, base);
        fs::write(root.join("file"), "same-change rewrite\n").unwrap();
        jj(&root, &["describe", "-m", "rewritten"]);
        let state = disk_state(&root);
        assert!(
            repository
                .refresh_checkout(1, 2, true, &[])
                .unwrap()
                .is_none()
        );
        assert_eq!(repository.load_file(1, 0).unwrap().after, ["original disk"]);
        assert_eq!(disk_state(&root), state);
        jj(&root, &["new"]);
        let parent = jj(&root, &["log", "--no-graph", "-r", "@-", "-T", "commit_id"]);
        fs::remove_file(root.join("removed")).unwrap();
        fs::write(root.join("added"), "new file\n").unwrap();
        let state = disk_state(&root);
        let mut comparison = repository
            .refresh_checkout(1, 2, true, &[(root.join("file"), "unsaved\n".into())])
            .unwrap()
            .map(checkout_comparison)
            .unwrap();
        assert_eq!(comparison.blame[0], initial.blame[0]);
        assert_eq!(comparison.blame[1].as_ref().unwrap().commit, parent);
        for (index, file) in comparison.files.iter_mut().enumerate() {
            *file = repository.load_file(2, index).unwrap();
        }
        assert_eq!(changed(&comparison, Path::new("file")).before, ["base"]);
        assert_eq!(changed(&comparison, Path::new("file")).after, ["unsaved"]);
        assert_eq!(
            changed(&comparison, Path::new("added")).status,
            FileStatus::Added
        );
        assert_eq!(
            changed(&comparison, Path::new("removed")).status,
            FileStatus::Removed
        );
        assert!(repository.load_file(1, 0).is_err());
        assert_eq!(disk_state(&root), state);
        assert!(
            repository
                .refresh_checkout(2, 3, true, &[])
                .unwrap()
                .is_none()
        );
        jj(&root, &["edit", &base]);
        assert!(
            repository
                .refresh_checkout(2, 3, true, &[])
                .unwrap()
                .is_none()
        );
        jj(&root, &["new", &base]);
        assert!(
            repository
                .refresh_checkout(2, 3, true, &[])
                .unwrap()
                .is_none()
        );
        let index = comparison
            .files
            .iter()
            .position(|file| file.path == Path::new("file"))
            .unwrap();
        assert_eq!(repository.load_file(2, index).unwrap().after, ["unsaved"]);
        repository
            .compare(
                10,
                &working(RepoKind::Jujutsu),
                &working(RepoKind::Jujutsu),
                ComparisonMode::Snapshots,
                &[(root.join("file"), "frozen after\n".into())],
            )
            .unwrap();
        fs::write(root.join("file"), "new checkout\n").unwrap();
        jj(&root, &["new"]);
        let refreshed = repository
            .refresh_checkout(10, 11, true, &[])
            .unwrap()
            .map(checkout_comparison)
            .unwrap();
        assert_eq!(refreshed.files.len(), 1);
        let file = repository.load_file(11, 0).unwrap();
        assert_eq!(file.before, ["base"]);
        assert_eq!(file.after, ["new checkout"]);
        let historical = revision(&base, RepoKind::Jujutsu);
        repository
            .compare(12, &historical, &historical, ComparisonMode::Snapshots, &[])
            .unwrap();
        jj(&root, &["new"]);
        assert!(
            repository
                .refresh_checkout(12, 13, true, &[])
                .unwrap()
                .is_none()
        );
        let tip_id = jj(&root, &["log", "--no-graph", "-r", "@", "-T", "commit_id"]);
        let pinned_tip = revision(&tip_id, RepoKind::Jujutsu);
        let pinned = repository
            .compare(20, &historical, &pinned_tip, ComparisonMode::Snapshots, &[])
            .unwrap();
        assert!(pinned.editable_paths.contains(Path::new("file")));
        let index = pinned
            .files
            .iter()
            .position(|file| file.path == Path::new("file"))
            .unwrap();
        assert_eq!(
            repository.load_file(20, index).unwrap().after,
            ["new checkout"]
        );
        fs::write(root.join("file"), "rewritten checkout\n").unwrap();
        jj(&root, &["describe", "-m", "same pinned change"]);
        let rewritten = jj(&root, &["log", "--no-graph", "-r", "@", "-T", "commit_id"]);
        assert_ne!(rewritten, tip_id);
        assert!(
            repository
                .refresh_checkout(20, 21, false, &[])
                .unwrap()
                .is_none()
        );
        assert_eq!(
            repository.load_file(20, index).unwrap().after,
            ["new checkout"]
        );
        let same_change = repository
            .compare(21, &historical, &pinned_tip, ComparisonMode::Snapshots, &[])
            .unwrap();
        assert_eq!(same_change.editable_paths, pinned.editable_paths);
        jj(&root, &["new"]);
        let readonly = repository
            .refresh_checkout(21, 22, false, &[(root.join("file"), "dirty live\n".into())])
            .unwrap()
            .map(checkout_comparison)
            .unwrap();
        assert!(readonly.editable_paths.is_empty());
        assert_eq!(readonly.before, pinned.before);
        assert_eq!(readonly.after, pinned.after);
        assert_eq!(readonly.files.len(), pinned.files.len());
        assert_eq!(
            repository.load_file(22, index).unwrap().after,
            ["new checkout"]
        );
        jj(&root, &["edit", &rewritten]);
        let promoted = repository
            .refresh_checkout(22, 23, false, &[])
            .unwrap()
            .map(checkout_comparison)
            .unwrap();
        assert_eq!(promoted.editable_paths, pinned.editable_paths);
        assert_eq!(
            repository.load_file(23, index).unwrap().after,
            ["new checkout"]
        );
    }
}

#[test]
fn branch_changes_resolves_local_and_private_remote_ancestry_without_active_mutation() {
    let fixture = Fixture::new();
    let active = fixture.dir("active\nquoted\"\\");
    init_git(&active);
    fs::write(active.join("common"), "base\n").unwrap();
    git(&active, &["add", "."]);
    git(&active, &["commit", "-m", "base"]);
    let base = git(&active, &["rev-parse", "HEAD"]);
    let source = fixture.0.join("source");
    git(
        &fixture.0,
        &["clone", active.to_str().unwrap(), source.to_str().unwrap()],
    );
    git(&source, &["config", "user.name", "Diff Test"]);
    git(&source, &["config", "user.email", "diff@example.invalid"]);
    fs::write(source.join("remote-only"), "remote\n").unwrap();
    git(&source, &["add", "."]);
    git(&source, &["commit", "-m", "remote"]);
    fs::write(active.join("local-only"), "local\n").unwrap();
    git(&active, &["add", "."]);
    git(&active, &["commit", "-m", "local"]);
    let local = revision(&git(&active, &["rev-parse", "HEAD"]), RepoKind::Git);
    git(
        &active,
        &["remote", "add", "origin", source.to_str().unwrap()],
    );
    let state = disk_state(&active);
    let mut repository = open(&active);
    let catalog = repository.list_remote("origin").unwrap();
    let remote = catalog
        .entries
        .iter()
        .find(|r| matches!(r.target, RevisionTarget::Remote { .. }))
        .unwrap();
    let branch = repository
        .compare(40, &local, remote, ComparisonMode::BranchChanges, &[])
        .unwrap();
    assert_eq!(branch.files.len(), 1);
    assert_eq!(branch.files[0].path, Path::new("remote-only"));
    assert!(branch.before.ends_with(&base));
    assert_eq!(branch.blame[0].as_ref().unwrap().commit, base);
    assert!(!branch.blame[1].as_ref().unwrap().store.starts_with(&active));
    assert_eq!(repository.load_file(40, 0).unwrap().after, ["remote"]);
    let reverse = repository
        .compare(41, remote, &local, ComparisonMode::BranchChanges, &[])
        .unwrap();
    assert_eq!(reverse.files.len(), 1);
    assert_eq!(reverse.files[0].path, Path::new("local-only"));
    assert_eq!(reverse.blame[0].as_ref().unwrap().commit, base);
    assert_eq!(reverse.blame[1].as_ref().unwrap().commit, local.label);
    assert_eq!(repository.load_file(41, 0).unwrap().after, ["local"]);
    assert!(
        repository
            .compare(42, &local, &local, ComparisonMode::BranchChanges, &[])
            .unwrap()
            .files
            .is_empty()
    );
    assert_eq!(disk_state(&active), state);
}

#[test]
fn branch_changes_rejects_missing_and_multiple_merge_bases_without_snapshot_fallback() {
    let fixture = Fixture::new();
    let root = fixture.dir("graphs");
    init_git(&root);
    fs::write(root.join("file"), "base\n").unwrap();
    git(&root, &["add", "."]);
    git(&root, &["commit", "-m", "base"]);
    let base = git(&root, &["rev-parse", "HEAD"]);
    let tree = git(&root, &["rev-parse", "HEAD^{tree}"]);
    let left = git(&root, &["commit-tree", &tree, "-p", &base, "-m", "left"]);
    let right = git(&root, &["commit-tree", &tree, "-p", &base, "-m", "right"]);
    let one = git(
        &root,
        &["commit-tree", &tree, "-p", &left, "-p", &right, "-m", "one"],
    );
    let two = git(
        &root,
        &["commit-tree", &tree, "-p", &right, "-p", &left, "-m", "two"],
    );
    let unrelated = git(&root, &["commit-tree", &tree, "-m", "unrelated"]);
    let state = disk_state(&root);
    let mut repository = open(&root);
    for (before, after, message) in [
        (&base, &unrelated, "no merge base"),
        (&one, &two, "multiple merge bases"),
    ] {
        let before = revision(before, RepoKind::Git);
        let after = revision(after, RepoKind::Git);
        assert!(
            repository
                .compare(50, &before, &after, ComparisonMode::BranchChanges, &[])
                .unwrap_err()
                .contains(message)
        );
        assert!(
            repository
                .compare(51, &before, &after, ComparisonMode::Snapshots, &[])
                .unwrap()
                .files
                .is_empty()
        );
    }
    assert_eq!(disk_state(&root), state);
}

#[test]
fn pull_request_refs_fetch_pinned_fork_heads_privately_for_git_and_jj() {
    let fixture = Fixture::new();
    let source = fixture.dir("source");
    init_git(&source);
    fs::write(source.join("common"), "base\n").unwrap();
    git(&source, &["add", "."]);
    git(&source, &["commit", "-m", "base"]);
    let base = git(&source, &["rev-parse", "HEAD"]);
    fs::write(source.join("target-only"), "not part of the PR\n").unwrap();
    git(&source, &["add", "."]);
    git(&source, &["commit", "-m", "target advanced"]);
    let target = git(&source, &["rev-parse", "HEAD"]);
    git(&source, &["checkout", "--detach", &base]);
    fs::write(source.join("common"), "fork change\n").unwrap();
    git(&source, &["add", "."]);
    git(&source, &["commit", "-m", "fork tip"]);
    let head = git(&source, &["rev-parse", "HEAD"]);
    git(&source, &["update-ref", "refs/pull/7/head", &head]);
    for (index, kind) in [RepoKind::Git, RepoKind::Jujutsu, RepoKind::Jujutsu]
        .into_iter()
        .enumerate()
    {
        let root = fixture.dir(&format!("active-{index}"));
        if kind == RepoKind::Git {
            init_git(&root);
            fs::write(root.join("unrelated"), "local\n").unwrap();
            git(&root, &["add", "."]);
            git(&root, &["commit", "-m", "unrelated local"]);
            git(
                &root,
                &["remote", "add", "origin", source.to_str().unwrap()],
            );
        } else {
            init_jj(&root, index == 2);
            jj(
                &root,
                &["git", "remote", "add", "origin", source.to_str().unwrap()],
            );
        }
        fs::write(root.join("unsaved"), "keep\n").unwrap();
        let state = disk_state(&root);
        let pinned = |reference: &str, id: &str| Revision {
            target: RevisionTarget::RemoteCommit {
                remote: "origin".into(),
                reference: reference.into(),
                id: id.into(),
            },
            ..revision(id, kind)
        };
        let before = pinned("refs/heads/local", &target);
        let after = pinned("refs/pull/7/head", &head);
        let mut repository = open(&root);
        let comparison = repository
            .compare(70, &before, &after, ComparisonMode::BranchChanges, &[])
            .unwrap();
        assert!(comparison.before.ends_with(&base));
        assert_eq!(comparison.files.len(), 1);
        assert_eq!(comparison.files[0].path, Path::new("common"));
        assert!(comparison.editable_paths.is_empty());
        let file = repository.load_file(70, 0).unwrap();
        assert_eq!(file.before, ["base"]);
        assert_eq!(file.after, ["fork change"]);
        assert_eq!(disk_state(&root), state);

        // A force-push cannot silently replace the immutable tip selected in the picker.
        let absent = pinned("refs/pull/7/head", &"f".repeat(40));
        assert!(
            repository
                .compare(71, &before, &absent, ComparisonMode::BranchChanges, &[])
                .unwrap_err()
                .contains("reopen :pull_requests")
        );
        assert_eq!(disk_state(&root), state);
    }
}

#[test]
fn jj_working_blame_captures_one_parent_and_never_selects_an_arbitrary_merge_parent() {
    let fixture = Fixture::new();
    let root = fixture.dir("blame-parents");
    init_jj(&root, false);
    fs::write(root.join("file"), "base\n").unwrap();
    jj(&root, &["describe", "-m", "base"]);
    let base = jj(&root, &["log", "--no-graph", "-r", "@", "-T", "commit_id"]);
    jj(&root, &["new"]);
    let state = disk_state(&root);
    let mut repository = open(&root);
    let one_parent = repository
        .compare(
            1,
            &working(RepoKind::Jujutsu),
            &working(RepoKind::Jujutsu),
            ComparisonMode::Snapshots,
            &[],
        )
        .unwrap();
    assert_eq!(one_parent.blame[0].as_ref().unwrap().commit, base);
    assert_eq!(one_parent.blame[0], one_parent.blame[1]);
    assert_eq!(disk_state(&root), state);
    jj(&root, &["new", "root()"]);
    fs::write(root.join("other"), "sibling\n").unwrap();
    jj(&root, &["describe", "-m", "sibling"]);
    let sibling = jj(&root, &["log", "--no-graph", "-r", "@", "-T", "commit_id"]);
    jj(&root, &["new", &base, &sibling]);
    let state = disk_state(&root);
    let merged = repository
        .compare(
            2,
            &working(RepoKind::Jujutsu),
            &working(RepoKind::Jujutsu),
            ComparisonMode::Snapshots,
            &[],
        )
        .unwrap();
    assert_eq!(merged.blame, [None, None]);
    assert_eq!(disk_state(&root), state);
}