orchestrator/tests/test_merge_gate.py

"""ORCH-043: tests for src/merge_gate core (TC-01..TC-11).

Git tests use REAL local repos in tmp (a bare 'origin' + a main clone), so
fetch / merge-base / rebase / push --force-with-lease are exercised without
network, mirroring tests/test_git_worktree.py. The re-test (pytest) and lease
units are isolated with monkeypatch / tmp files.
"""
import json
import os
import subprocess
import tempfile
import time

import pytest

# Env before importing app modules (same convention as the other suites).
_test_db = os.path.join(tempfile.gettempdir(), "test_orchestrator_merge_gate.db")
os.environ["ORCH_DB_PATH"] = _test_db
os.environ["ORCH_REPOS_DIR"] = tempfile.gettempdir()
os.environ["ORCH_GITEA_TOKEN"] = "test-token"
os.environ["ORCH_PLANE_API_TOKEN"] = "test-token"

from src import git_worktree, merge_gate  # noqa: E402


def _git(cwd, *args):
    return subprocess.run(["git", "-C", cwd, *args], capture_output=True, text=True)


def _origin_sha(origin, ref):
    return _git(str(origin), "rev-parse", ref).stdout.strip()


@pytest.fixture
def repos(tmp_path, monkeypatch):
    """Bare 'origin' (main@C1) + main clone + two feature branches branched from C0.

    Layout:
      C0  README.md
      feature/behind   : C0 + adds f.txt           (rebases cleanly onto C1)
      feature/conflict : C0 + edits README.md       (textual conflict with C1)
      feature/uptodate : branched from C1            (already contains origin/main)
      main C1          : edits README.md + adds other.txt
    Returns (repo_name, origin_path).
    """
    repo = "orchestrator"
    repos_dir = tmp_path / "repos"
    wt_dir = tmp_path / "repos" / "_wt"
    repos_dir.mkdir(parents=True)

    monkeypatch.setattr(merge_gate.settings, "repos_dir", str(repos_dir))
    monkeypatch.setattr(git_worktree.settings, "repos_dir", str(repos_dir))
    monkeypatch.setattr(git_worktree.settings, "worktrees_dir", str(wt_dir))

    origin = tmp_path / "origin.git"
    subprocess.run(["git", "init", "--bare", "-b", "main", str(origin)], capture_output=True)

    seed = tmp_path / "seed"
    seed.mkdir()
    _git(str(seed), "init", "-b", "main")
    _git(str(seed), "config", "user.email", "t@t")
    _git(str(seed), "config", "user.name", "t")
    (seed / "README.md").write_text("base\n")
    _git(str(seed), "add", ".")
    _git(str(seed), "commit", "-m", "C0")
    _git(str(seed), "remote", "add", "origin", str(origin))
    _git(str(seed), "push", "origin", "main")

    # Branches off C0.
    _git(str(seed), "checkout", "-b", "feature/behind")
    (seed / "f.txt").write_text("feature\n")
    _git(str(seed), "add", ".")
    _git(str(seed), "commit", "-m", "feat: add f.txt")
    _git(str(seed), "push", "origin", "feature/behind")

    _git(str(seed), "checkout", "main")
    _git(str(seed), "checkout", "-b", "feature/conflict")
    (seed / "README.md").write_text("feature readme\n")
    _git(str(seed), "add", ".")
    _git(str(seed), "commit", "-m", "feat: edit README")
    _git(str(seed), "push", "origin", "feature/conflict")

    # Advance main to C1.
    _git(str(seed), "checkout", "main")
    (seed / "README.md").write_text("main v2\n")
    (seed / "other.txt").write_text("main change\n")
    _git(str(seed), "add", ".")
    _git(str(seed), "commit", "-m", "C1")
    _git(str(seed), "push", "origin", "main")

    # Branch that already contains C1.
    _git(str(seed), "checkout", "-b", "feature/uptodate")
    (seed / "g.txt").write_text("uptodate\n")
    _git(str(seed), "add", ".")
    _git(str(seed), "commit", "-m", "feat: on top of C1")
    _git(str(seed), "push", "origin", "feature/uptodate")

    # Main clone at repos_dir/<repo>.
    main_clone = repos_dir / repo
    subprocess.run(["git", "clone", str(origin), str(main_clone)], capture_output=True)
    _git(str(main_clone), "config", "user.email", "t@t")
    _git(str(main_clone), "config", "user.name", "t")
    return repo, origin


# ---------------------------------------------------------------------------
# TC-01..03: branch_is_behind_main
# ---------------------------------------------------------------------------
def test_tc01_behind_when_main_ahead(repos):
    repo, _ = repos
    assert merge_gate.branch_is_behind_main(repo, "feature/behind") is True


def test_tc02_not_behind_when_branch_contains_main(repos):
    repo, _ = repos
    assert merge_gate.branch_is_behind_main(repo, "feature/uptodate") is False


def test_tc03_never_raises_on_bad_repo(monkeypatch, tmp_path):
    # Point repos_dir at an empty dir -> ensure_worktree raises -> caught -> True.
    monkeypatch.setattr(merge_gate.settings, "repos_dir", str(tmp_path / "nope"))
    monkeypatch.setattr(git_worktree.settings, "repos_dir", str(tmp_path / "nope"))
    monkeypatch.setattr(git_worktree.settings, "worktrees_dir", str(tmp_path / "_wt"))
    result = merge_gate.branch_is_behind_main("orchestrator", "feature/x")
    assert result is True  # safe bool, not an exception


# ---------------------------------------------------------------------------
# TC-04..06: auto_rebase_onto_main
# ---------------------------------------------------------------------------
def test_tc04_clean_catchup_pushes_with_lease(repos):
    repo, origin = repos
    main_before = _origin_sha(origin, "main")

    ok, reason = merge_gate.auto_rebase_onto_main(repo, "feature/behind")
    assert ok is True, reason

    # origin/main must be UNTOUCHED (AC-7).
    assert _origin_sha(origin, "main") == main_before
    # The pushed branch now contains origin/main (origin/main is its ancestor).
    rc = subprocess.run(
        ["git", "-C", str(origin), "merge-base", "--is-ancestor",
         "main", "feature/behind"],
        capture_output=True,
    ).returncode
    assert rc == 0
    # And it carries main's new file plus its own.
    assert _git(str(origin), "cat-file", "-e", "feature/behind:other.txt").returncode == 0
    assert _git(str(origin), "cat-file", "-e", "feature/behind:f.txt").returncode == 0


def test_tc05_conflict_aborts_clean_and_reports(repos):
    repo, origin = repos
    main_before = _origin_sha(origin, "main")
    branch_before = _origin_sha(origin, "feature/conflict")

    ok, reason = merge_gate.auto_rebase_onto_main(repo, "feature/conflict")
    assert ok is False
    assert "rebase conflict" in reason
    # main untouched, branch NOT force-pushed past the conflict.
    assert _origin_sha(origin, "main") == main_before
    assert _origin_sha(origin, "feature/conflict") == branch_before
    # Worktree left clean (no rebase in progress).
    wt = git_worktree.get_worktree_path(repo, "feature/conflict")
    assert not os.path.isdir(os.path.join(wt, ".git", "rebase-merge"))
    assert not os.path.isdir(os.path.join(wt, ".git", "rebase-apply"))


def test_tc06_never_pushes_main(repos, monkeypatch):
    repo, origin = repos
    calls = []
    real_run = subprocess.run

    def _spy(cmd, *a, **k):
        if isinstance(cmd, list):
            calls.append(cmd)
        return real_run(cmd, *a, **k)

    monkeypatch.setattr(merge_gate.subprocess, "run", _spy)
    merge_gate.auto_rebase_onto_main(repo, "feature/behind")

    pushes = [c for c in calls if "push" in c]
    assert pushes, "expected at least one push"
    for c in pushes:
        # Never push main; force only via --force-with-lease on the task branch.
        assert "main" not in c, f"push touched main: {c}"
        assert "--force-with-lease" in c
        assert "feature/behind" in c
        # Hard force must never be used.
        assert "--force" not in c or "--force-with-lease" in c
        assert "-f" not in c


# ---------------------------------------------------------------------------
# TC-07..09: retest_branch (isolated from real pytest)
# ---------------------------------------------------------------------------
@pytest.fixture
def fake_worktree(tmp_path, monkeypatch):
    wt = tmp_path / "wt"
    wt.mkdir()
    monkeypatch.setattr(merge_gate, "get_worktree_path", lambda repo, branch: str(wt))
    return str(wt)


def test_tc07_retest_green(fake_worktree, monkeypatch):
    monkeypatch.setattr(
        merge_gate.subprocess, "run",
        lambda *a, **k: subprocess.CompletedProcess(a, 0, "1 passed", ""),
    )
    ok, reason = merge_gate.retest_branch("orchestrator", "feature/x")
    assert ok is True
    assert reason == "re-test green"


def test_tc08_retest_red_with_tail(fake_worktree, monkeypatch):
    monkeypatch.setattr(
        merge_gate.subprocess, "run",
        lambda *a, **k: subprocess.CompletedProcess(
            a, 1, "FAILED tests/test_x.py::t - AssertionError\n1 failed", ""
        ),
    )
    ok, reason = merge_gate.retest_branch("orchestrator", "feature/x")
    assert ok is False
    assert "re-test failed" in reason
    assert "AssertionError" in reason  # output tail embedded


def test_tc09_retest_timeout(fake_worktree, monkeypatch):
    def _boom(*a, **k):
        raise subprocess.TimeoutExpired(cmd="pytest", timeout=1)

    monkeypatch.setattr(merge_gate.settings, "merge_retest_timeout_s", 1)
    monkeypatch.setattr(merge_gate.subprocess, "run", _boom)
    ok, reason = merge_gate.retest_branch("orchestrator", "feature/x")
    assert ok is False
    assert "re-test timeout" in reason


# ---------------------------------------------------------------------------
# TC-10..11: merge-lease (serialisation)
# ---------------------------------------------------------------------------
@pytest.fixture
def lease_dir(tmp_path, monkeypatch):
    d = tmp_path / "repos"
    d.mkdir()
    monkeypatch.setattr(merge_gate.settings, "repos_dir", str(d))
    monkeypatch.setattr(merge_gate.settings, "merge_lock_timeout_s", 300)
    return d


def test_tc10_second_acquire_busy_until_released(lease_dir):
    repo = "orchestrator"
    ok, _ = merge_gate.acquire_merge_lease(repo, "feature/A", "ORCH-1")
    assert ok is True

    # A different branch cannot acquire while held.
    ok2, reason2 = merge_gate.acquire_merge_lease(repo, "feature/B", "ORCH-2")
    assert ok2 is False
    assert reason2 == "merge-lock busy"

    # Same holder is idempotent.
    ok_self, _ = merge_gate.acquire_merge_lease(repo, "feature/A", "ORCH-1")
    assert ok_self is True

    # Release (holder-aware) frees it for B.
    merge_gate.release_merge_lease(repo, "feature/A")
    ok3, _ = merge_gate.acquire_merge_lease(repo, "feature/B", "ORCH-2")
    assert ok3 is True


def test_tc10_release_is_holder_aware(lease_dir):
    repo = "orchestrator"
    merge_gate.acquire_merge_lease(repo, "feature/A", "ORCH-1")
    # A stale release from a DIFFERENT branch must NOT drop A's lease.
    merge_gate.release_merge_lease(repo, "feature/OTHER")
    ok, reason = merge_gate.acquire_merge_lease(repo, "feature/B", "ORCH-2")
    assert ok is False and reason == "merge-lock busy"


def test_tc11_stale_lease_is_reclaimed(lease_dir, monkeypatch):
    repo = "orchestrator"
    monkeypatch.setattr(merge_gate.settings, "merge_lock_timeout_s", 10)
    # Write a lease that is older than the timeout (orphaned by a dead process).
    path = merge_gate._lease_path(repo)
    with open(path, "w", encoding="utf-8") as f:
        json.dump(
            {"branch": "feature/dead", "acquired_at": time.time() - 999, "pid": 1},
            f,
        )
    ok, reason = merge_gate.acquire_merge_lease(repo, "feature/new", "ORCH-9")
    assert ok is True
    assert "reclaimed" in reason
    # The new holder now owns it.
    held = json.load(open(path, encoding="utf-8"))
    assert held["branch"] == "feature/new"


def test_tc11_release_missing_is_noop(lease_dir):
    # Releasing a non-existent lease never raises.
    merge_gate.release_merge_lease("orchestrator", "feature/none")
    merge_gate.release_merge_lease("orchestrator")  # force form