lernie 0.0.2

A git-backed agent harness
Documentation 
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//! Tests for checkpoint trigger evaluation (ARCH §6).
//!
//! [`due`] is pure — driven by constructed states. [`state`]'s git
//! derivation runs against a real repo so the last-checkpoint grep and the
//! commit-count / elapsed-time measures are exercised end-to-end.

use super::*;
use crate::config::workflow::{CompactionConfig, IntermediateCompaction};
use crate::template::RealGit;
use tempfile::TempDir;

fn cfg(trigger: CompactionTrigger, n: Option<u32>) -> CompactionConfig {
    CompactionConfig {
        intermediate: IntermediateCompaction { trigger, n },
    }
}

fn st(commits: u32, seconds: u64, flush: bool) -> CheckpointState {
    CheckpointState {
        commits_since_checkpoint: commits,
        seconds_since_checkpoint: seconds,
        flush_requested: flush,
    }
}

#[test]
fn no_config_never_compacts() {
    assert!(!due(None, &st(1000, 1000, true)));
}

#[test]
fn every_n_commits_fires_at_or_past_the_threshold() {
    let c = cfg(CompactionTrigger::EveryNCommits, Some(3));
    assert!(!due(Some(&c), &st(2, 0, false)));
    assert!(due(Some(&c), &st(3, 0, false)));
    assert!(due(Some(&c), &st(4, 0, false)));
}

#[test]
fn every_t_seconds_fires_at_or_past_the_threshold() {
    let c = cfg(CompactionTrigger::EveryTSeconds, Some(10));
    assert!(!due(Some(&c), &st(0, 9, false)));
    assert!(due(Some(&c), &st(0, 10, false)));
}

#[test]
fn on_flush_fires_only_when_the_agent_elects_it() {
    let c = cfg(CompactionTrigger::OnFlush, None);
    assert!(!due(Some(&c), &st(9999, 9999, false)));
    assert!(due(Some(&c), &st(0, 0, true)));
}

#[test]
fn a_malformed_threshold_fails_closed() {
    // n absent or zero (guarded at config load, §6) is never due — a bad
    // config does not compact every step.
    assert!(!due(
        Some(&cfg(CompactionTrigger::EveryNCommits, None)),
        &st(100, 0, false)
    ));
    assert!(!due(
        Some(&cfg(CompactionTrigger::EveryTSeconds, Some(0))),
        &st(0, 100, false)
    ));
}

// ---- real-git state derivation ---------------------------------------

fn init(wt: &Path) {
    let g = RealGit::new();
    g.run(wt, &["init", "-b", "agents/p1"]).unwrap();
    g.run(wt, &["config", "user.email", "t@t"]).unwrap();
    g.run(wt, &["config", "user.name", "t"]).unwrap();
}

fn commit(wt: &Path, subject: &str, rel: &str, content: &str) {
    let g = RealGit::new();
    let f = wt.join(rel);
    std::fs::create_dir_all(f.parent().unwrap()).unwrap();
    std::fs::write(&f, content).unwrap();
    g.run(wt, &["add", "-A"]).unwrap();
    g.run(wt, &["commit", "-m", subject]).unwrap();
}

fn now_of(wt: &Path) -> u64 {
    RealGit::new()
        .run_capture(wt, &["log", "-n", "1", "--format=%ct", "HEAD"])
        .unwrap()
        .trim()
        .parse()
        .unwrap()
}

#[test]
fn state_counts_the_whole_branch_when_no_checkpoint_landed() {
    let dir = TempDir::new().unwrap();
    let wt = dir.path();
    init(wt);
    commit(wt, "root", "a.txt", "1");
    // Anchor `now` on the root commit's own committer time (read back
    // from git while it is HEAD), so the expected elapsed is exact.
    // (Anchoring on the *second* commit's time assumed both commits
    // land in the same wall second — two real `git commit` runs under
    // load can straddle it.)
    let root_ct = now_of(wt);
    commit(wt, "step", "b.txt", "2");
    let s = state(wt, root_ct + 7, false, &RealGit::new()).unwrap();
    assert_eq!(s.commits_since_checkpoint, 2, "root + one step");
    assert_eq!(s.seconds_since_checkpoint, 7, "measured from the root");
    assert!(!s.flush_requested);
}

#[test]
fn state_measures_from_the_last_compaction_merge() {
    let dir = TempDir::new().unwrap();
    let wt = dir.path();
    init(wt);
    commit(wt, "root", "a.txt", "1");
    commit(wt, "compaction merge [p1-cmp]", "summary/001.md", "x");
    // Anchor `now` on the checkpoint commit's committer time (it is
    // HEAD right here) so the expected elapsed is exact rather than a
    // lower bound racing the wall clock.
    let cmp_ct = now_of(wt);
    commit(wt, "step after", "b.txt", "2");
    let s = state(wt, cmp_ct + 42, true, &RealGit::new()).unwrap();
    assert_eq!(s.commits_since_checkpoint, 1, "only the post-merge step");
    // Elapsed is measured from the checkpoint commit, not the root.
    assert_eq!(s.seconds_since_checkpoint, 42);
    assert!(s.flush_requested);
}

#[test]
fn state_saturates_when_now_precedes_the_checkpoint() {
    let dir = TempDir::new().unwrap();
    let wt = dir.path();
    init(wt);
    commit(wt, "root", "a.txt", "1");
    let s = state(wt, 0, false, &RealGit::new()).unwrap();
    assert_eq!(s.seconds_since_checkpoint, 0, "no negative elapsed time");
}

#[test]
fn state_surfaces_a_git_failure() {
    // A non-repo directory: the first rev-parse/log fails loudly.
    let dir = TempDir::new().unwrap();
    let err = state(dir.path(), 0, false, &RealGit::new()).unwrap_err();
    assert!(matches!(err, Error::Git { .. }), "{err:?}");
}

// ---- per-op git failures, via a stub -----------------------------------
//
// Real git can only fail wholesale (the test above); each later derivation
// step's `op` tag needs a git that fails at exactly that step. The stub
// answers every capture except the one whose args contain `fail_on`.

struct FailOn(&'static str);

impl GitRunner for FailOn {
    fn run(&self, _dest: &Path, _args: &[&str]) -> std::io::Result<()> {
        unreachable!("checkpoint derivation only captures")
    }
    fn run_capture(&self, _dest: &Path, args: &[&str]) -> std::io::Result<String> {
        if args.iter().any(|a| a.contains(self.0)) {
            return Err(std::io::Error::other("stub git failure"));
        }
        // Benign answers: no checkpoint landed (empty grep), one commit,
        // a root sha, epoch second 100.
        Ok(match args {
            a if a.contains(&"--grep") => String::new(),
            a if a.contains(&"--count") => "1".to_string(),
            a if a.contains(&"--max-parents=0") => "r00t".to_string(),
            _ => "100".to_string(),
        })
    }
}

fn op_of(err: Error) -> &'static str {
    match err {
        Error::Git { op, .. } => op,
        other => panic!("expected Error::Git, got {other:?}"),
    }
}

#[test]
fn state_tags_a_commit_count_failure_with_its_op() {
    let dir = TempDir::new().unwrap();
    let err = state(dir.path(), 0, false, &FailOn("--count")).unwrap_err();
    assert_eq!(op_of(err), "checkpoint rev-list count");
}

#[test]
fn state_tags_a_commit_time_failure_with_its_op() {
    let dir = TempDir::new().unwrap();
    let err = state(dir.path(), 0, false, &FailOn("%ct")).unwrap_err();
    assert_eq!(op_of(err), "checkpoint commit time");
}

#[test]
fn state_tags_a_root_lookup_failure_with_its_op() {
    let dir = TempDir::new().unwrap();
    let err = state(dir.path(), 0, false, &FailOn("--max-parents=0")).unwrap_err();
    assert_eq!(op_of(err), "checkpoint root rev-list");
}