test: search-index concurrency for rebuild, queries, and lock order (#139)

* test: concurrency suite for search-index rebuild, pointer swap, and query

* test: exercise background rebuild and lock order in concurrency suite

* test: fix ruff and mypy on search-index concurrency tests

* fix: stoppable background worker and stronger concurrency test oracles

* fix: keep background worker ownership until stop is confirmed

* address per comment

* fix docstring

* Pin locked-index live-scan fallback in concurrency test

Author: clean6378-max-it

tests/conftest.py

@@ -2,16 +2,32 @@
 
 from __future__ import annotations
 
+import json
 import os
 import shutil
 from collections.abc import Mapping
 from pathlib import Path
+from unittest.mock import patch
 
 import pytest
 from hypothesis import settings
 
 from app import create_app
 
+
+def write_session(path: Path, lines: list[dict[str, object]]) -> None:
+    """Write JSONL session *lines* to *path*, creating parent directories."""
+    path.parent.mkdir(parents=True, exist_ok=True)
+    with path.open("w", encoding="utf-8") as handle:
+        for line in lines:
+            handle.write(json.dumps(line, ensure_ascii=False) + "\n")
+
+
+def index_patches(cache_root: Path):
+    """Return the patch context managers that point the index at *cache_root*."""
+    return (patch("utils.search_index.cache_dir", return_value=cache_root),)
+
+
 # Hypothesis profiles drive fuzz example counts/deadlines (deadline disabled to
 # avoid timing flakiness on slow/CI runners). CI runs fewer examples for speed.
 settings.register_profile("dev", max_examples=200, deadline=None)
@@ -67,7 +83,7 @@ def client(tmp_path, export_state_file):
 
 @pytest.fixture
 def client_single(tmp_path, export_state_file):
-    """Flask test client with one seeded session ? for search/limit tests."""
+    """Flask test client with one seeded session for search/limit tests."""
     return _make_test_client(tmp_path, {"session_abc123.jsonl": "session_minimal.jsonl"})
 
 

tests/test_search_index.py

@@ -2,7 +2,6 @@
 
 from __future__ import annotations
 
-import json
 import sqlite3
 from contextlib import closing, contextmanager
 from datetime import UTC, datetime, timedelta
@@ -12,6 +11,7 @@
 import pytest
 
 from api.search import _resolve_search_results, _search_via_index
+from tests.conftest import index_patches as _index_patches, write_session as _write_session
 from utils.exclusion_rules import load_rules
 from utils.search_index import (
     build_search_index,
@@ -26,17 +26,6 @@
 )
 
 
-def _write_session(path: Path, lines: list[dict[str, object]]) -> None:
-    path.parent.mkdir(parents=True, exist_ok=True)
-    with path.open("w", encoding="utf-8") as handle:
-        for line in lines:
-            handle.write(json.dumps(line, ensure_ascii=False) + "\n")
-
-
-def _index_patches(cache_root: Path):
-    return (patch("utils.search_index.cache_dir", return_value=cache_root),)
-
-
 @pytest.fixture
 def indexed_tree(tmp_path, monkeypatch):
     """Temp projects dir + isolated search index cache."""
@@ -381,11 +370,15 @@ def test_background_worker_starts_once(self, indexed_tree, monkeypatch):
             patches[0],
             patch("utils.search_index.threading.Thread") as mock_thread,
         ):
+            # The mock worker is not a real thread; report it as stopped so the
+            # teardown reset does not treat it as a live worker that won't join.
+            mock_thread.return_value.is_alive.return_value = False
             start_search_index_background(indexed_tree["projects"], [])
             start_search_index_background(indexed_tree["projects"], [])
             assert mock_thread.call_count == 1
             assert mock_thread.call_args.kwargs.get("daemon") is True
             assert mock_thread.return_value.start.call_count == 1
+        reset_background_for_tests()
 
 
 class TestIndexSearchCompleteness: