fix(windows-tests): address parallel runner encoding and symlink privilege errors (Fixes #39480)

tests/conftest.py

@@ -1049,6 +1049,12 @@ def pytest_configure(config):  # noqa: D401 — pytest hook
         f"{_ALLOW_MACOS_KEYCHAIN_MARK}: allow a test to exercise the macOS "
         "Keychain credential reader with its own subprocess/platform mocks.",
     )
+    config.addinivalue_line(
+        "markers",
+        "require_symlinks: skip the test if symbolic links cannot be "
+        "created in the current environment (needs admin/developer mode "
+        "on Windows).",
+    )
 
     # The pyproject addopts pin ``--timeout-method=signal`` relies on
     # ``signal.SIGALRM``, which does not exist on Windows — pytest-timeout
@@ -1059,6 +1065,36 @@ def pytest_configure(config):  # noqa: D401 — pytest hook
         config.option.timeout_method = "thread"
 
 
+_symlink_supported_cache = None
+
+
+def _check_symlink_support() -> bool:
+    global _symlink_supported_cache
+    if _symlink_supported_cache is not None:
+        return _symlink_supported_cache
+
+    try:
+        with tempfile.TemporaryDirectory() as d:
+            src = Path(d) / "src"
+            src.touch()
+            lnk = Path(d) / "lnk"
+            lnk.symlink_to(src)
+            _symlink_supported_cache = True
+            return True
+    except OSError:
+        _symlink_supported_cache = False
+        return False
+
+
+def pytest_runtest_setup(item):
+    if item.get_closest_marker("require_symlinks"):
+        if not _check_symlink_support():
+            pytest.skip(
+                "Environment does not support symbolic links "
+                "(requires admin/developer mode on Windows)"
+            )
+
+
 def pytest_collection_modifyitems(config, items):  # noqa: D401 — pytest hook
     """Skip ``requires_wal`` tests when the linked SQLite can't use WAL.
 

tests/test_atomic_replace_symlinks.py

@@ -43,6 +43,7 @@ def _write_tmp(dir_: Path, content: str) -> Path:
     return tmp
 
 
+@pytest.mark.require_symlinks
 def test_atomic_replace_preserves_symlink(tmp_path: Path) -> None:
     real = tmp_path / "real.yaml"
     link = tmp_path / "link.yaml"
@@ -91,6 +92,7 @@ def test_atomic_replace_accepts_pathlike_and_str(tmp_path: Path) -> None:
 # ─── atomic_json_write / atomic_yaml_write wiring ──────────────────────────
 
 
+@pytest.mark.require_symlinks
 def test_atomic_json_write_preserves_symlink(tmp_path: Path) -> None:
     real = tmp_path / "real.json"
     link = tmp_path / "link.json"
@@ -104,6 +106,7 @@ def test_atomic_json_write_preserves_symlink(tmp_path: Path) -> None:
     assert loaded == {"hello": "world"}
 
 
+@pytest.mark.require_symlinks
 def test_atomic_yaml_write_preserves_symlink(tmp_path: Path) -> None:
     real = tmp_path / "real.yaml"
     link = tmp_path / "link.yaml"
@@ -117,6 +120,7 @@ def test_atomic_yaml_write_preserves_symlink(tmp_path: Path) -> None:
     assert data == {"model": {"provider": "openrouter"}}
 
 
+@pytest.mark.require_symlinks
 def test_atomic_json_write_preserves_symlink_permissions(tmp_path: Path) -> None:
     """Symlinked targets keep the real file's permission bits."""
     if os.name != "posix":
@@ -171,6 +175,7 @@ def test_atomic_yaml_write_restores_owner_on_real_symlink_target(
 # ─── Broken-symlink edge case ─────────────────────────────────────────────
 
 
+@pytest.mark.require_symlinks
 def test_atomic_replace_broken_symlink_creates_target(tmp_path: Path) -> None:
     """A symlink pointing at a missing file: the write should create the
     real target (resolving via realpath) rather than leaving the dangling

tests/test_hermes_constants.py

@@ -505,6 +505,7 @@ class TestSecureParentDir:
 
 
 
+    @pytest.mark.require_symlinks
     def test_symlink_resolved(self, tmp_path, monkeypatch):
         """Symlinks should be resolved before checking depth."""
         real_dir = tmp_path / "a" / "b"