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Prevent detached Git maintenance from racing sparse fixture cleanup #4857

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Merged
Mister-Meeseeks merged 1 commit into from
Oct 23, 2026
Merged

Prevent detached Git maintenance from racing sparse fixture cleanup #4857

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33 changes: 33 additions & 0 deletions tests/test_research_baseline_sparse.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2,11 +2,13 @@
import contextlib
import io
import json
import os
from pathlib import Path
import subprocess
import sys
import tempfile
import unittest
from unittest import mock

ROOT = Path(__file__).resolve().parents[1]
sys.path.insert(0, str(ROOT / "scripts"))
Expand Down Expand Up @@ -50,7 +52,9 @@ def git(self, *args):
text=True, encoding="utf-8").stdout

def commit(self, message, *extra):
# Detached maintenance can recreate .git/objects during temp cleanup.
self.git("-c", "user.name=Fixture", "-c", "user.email=fixture@example.invalid",
"-c", "maintenance.auto=false", "-c", "gc.auto=0",
"-c", "core.hooksPath=/dev/null", "commit", "-q", *extra, "-m", message)

def run_main(self):
Expand Down Expand Up @@ -82,6 +86,35 @@ def test_full_checkout_reports_nothing(self):
self.assertEqual((code, result["status"]), (0, "NO_SPARSE_SELECTED_OMISSIONS"))
self.assertEqual(result["next"], ["python3", "-B", "scripts/research_baseline.py"])

def test_fixture_commit_never_starts_background_maintenance(self):
# Force automatic work even in this tiny repo. Keep the positive
# control synchronous so its own maintenance cannot race cleanup.
for key, value in {
"maintenance.auto": "true", "maintenance.autoDetach": "false",
"gc.autoDetach": "false", "maintenance.commit-graph.enabled": "true",
"maintenance.commit-graph.auto": "-1", "gc.auto": "1",
}.items():
self.git("config", key, value)
with tempfile.TemporaryDirectory() as directory:
trace = Path(directory) / "git-trace.jsonl"

def maintenance_children():
return [event for line in trace.read_text(encoding="utf-8").splitlines()
if (event := json.loads(line)).get("event") == "child_start"
and any(arg in {"maintenance", "gc"}
for arg in event.get("argv", []))]

with mock.patch.dict(os.environ, {"GIT_TRACE2_EVENT": str(trace)}):
self.commit("guarded fixture", "--allow-empty")
self.assertEqual(maintenance_children(), [])

trace.unlink()
with mock.patch.dict(os.environ, {"GIT_TRACE2_EVENT": str(trace)}):
self.git("-c", "user.name=Fixture", "-c", "user.email=fixture@example.invalid",
"-c", "core.hooksPath=/dev/null", "commit", "-q", "--allow-empty",
"-m", "unguarded positive control")
self.assertTrue(maintenance_children(), "positive control must start maintenance")

def test_full_explicit_inventory_keeps_repository_relative_paths(self):
self.explicit_manifest()
code, result = self.run_main()
Expand Down