fix(testing): keep duration cache repo-relative

scripts/run_tests_parallel.py

@@ -45,7 +45,7 @@
 import threading
 import time
 from concurrent.futures import ThreadPoolExecutor, Future
-from pathlib import Path
+from pathlib import Path, PurePosixPath, PureWindowsPath
 from typing import Dict, List, Tuple
 
 
@@ -388,6 +388,22 @@ def _format_file(file: Path, repo_root: Path) -> str:
         return str(file)
 
 
+def _duration_cache_key(file: Path, repo_root: Path) -> str | None:
+    """Return a portable duration-cache key for repo-local files only."""
+    try:
+        return str(file.resolve().relative_to(repo_root.resolve()))
+    except ValueError:
+        return None
+
+
+def _is_portable_duration_key(key: str) -> bool:
+    """Duration caches are portable only when keys are repo-relative."""
+    return not (
+        PurePosixPath(key).is_absolute()
+        or PureWindowsPath(key).is_absolute()
+    )
+
+
 def _print_progress(
     tests_done: int,
     total_tests: int,
@@ -519,9 +535,15 @@ def _save_durations(
     repo-relative paths so the cache is portable across checkouts
     and CI runners.
     """
-    data: dict[str, float] = _load_durations(repo_root)
+    data: dict[str, float] = {
+        key: value
+        for key, value in _load_durations(repo_root).items()
+        if _is_portable_duration_key(key)
+    }
     for f, t in file_times:
-        key = _format_file(f, repo_root)
+        key = _duration_cache_key(f, repo_root)
+        if key is None:
+            continue
         data[key] = round(t, 3)
     path = repo_root / _DURATIONS_FILE
     path.write_text(json.dumps(data, indent=2, sort_keys=True) + "\n")

tests/test_run_tests_parallel.py

@@ -63,6 +63,46 @@ def _pid_alive(pid: int) -> bool:
     return True
 
 
+def test_duration_cache_skips_paths_outside_repo(tmp_path: Path) -> None:
+    from scripts.run_tests_parallel import _DURATIONS_FILE, _save_durations
+
+    repo_root = tmp_path / "repo"
+    repo_file = repo_root / "tests" / "test_repo.py"
+    outside_file = tmp_path / "outside" / "test_external.py"
+    repo_file.parent.mkdir(parents=True)
+    outside_file.parent.mkdir(parents=True)
+    repo_file.write_text("def test_repo():\n    assert True\n", encoding="utf-8")
+    outside_file.write_text("def test_external():\n    assert True\n", encoding="utf-8")
+
+    _save_durations([(repo_file, 1.234), (outside_file, 9.876)], repo_root)
+
+    data = json.loads((repo_root / _DURATIONS_FILE).read_text(encoding="utf-8"))
+    assert data == {str(Path("tests") / "test_repo.py"): 1.234}
+
+
+def test_duration_cache_drops_stale_absolute_keys(tmp_path: Path) -> None:
+    from scripts.run_tests_parallel import _DURATIONS_FILE, _save_durations
+
+    repo_root = tmp_path / "repo"
+    repo_root.mkdir()
+    cache = repo_root / _DURATIONS_FILE
+    cache.write_text(
+        json.dumps(
+            {
+                "/tmp/hermes/test_external.py": 1.0,
+                r"C:\Users\runner\AppData\Local\Temp\test_external.py": 2.0,
+                "tests/test_existing.py": 3.0,
+            }
+        ),
+        encoding="utf-8",
+    )
+
+    _save_durations([], repo_root)
+
+    data = json.loads(cache.read_text(encoding="utf-8"))
+    assert data == {"tests/test_existing.py": 3.0}
+
+
 @pytest.mark.skipif(sys.platform == "win32", reason="POSIX-only probe")
 @pytest.mark.live_system_guard_bypass
 def test_grandchild_leak_is_killed_by_runner(tmp_path: Path) -> None: