fix(platform): harden Windows lock detection

Recognize win32 as a Windows platform alias and wrap missing platform lock modules in SwarmLockUnavailableError instead of leaking raw ImportError.

Based-on: #34

Author: SABUJ123472

src/openharness/platforms.py

@@ -37,7 +37,7 @@ def detect_platform(
 
     if system == "darwin":
         return "macos"
-    if system == "windows":
+    if system in {"windows", "win32"}:
         return "windows"
     if system == "linux":
         if "microsoft" in kernel_release or env_map.get("WSL_DISTRO_NAME") or env_map.get("WSL_INTEROP"):
@@ -84,4 +84,3 @@ def get_platform_capabilities(platform_name: PlatformName | None = None) -> Plat
         supports_sandbox_runtime=False,
         supports_docker_sandbox=False,
     )
-

src/openharness/utils/file_lock.py

@@ -46,7 +46,10 @@ def exclusive_file_lock(
 
 @contextmanager
 def _exclusive_posix_lock(lock_path: Path) -> Iterator[None]:
-    import fcntl
+    try:
+        import fcntl
+    except ImportError as exc:
+        raise SwarmLockUnavailableError(f"fcntl not available: {exc}") from exc
 
     lock_path.parent.mkdir(parents=True, exist_ok=True)
     lock_path.touch(exist_ok=True)
@@ -60,7 +63,10 @@ def _exclusive_posix_lock(lock_path: Path) -> Iterator[None]:
 
 @contextmanager
 def _exclusive_windows_lock(lock_path: Path) -> Iterator[None]:
-    import msvcrt
+    try:
+        import msvcrt
+    except ImportError as exc:
+        raise SwarmLockUnavailableError(f"msvcrt not available: {exc}") from exc
 
     lock_path.parent.mkdir(parents=True, exist_ok=True)
     with lock_path.open("a+b") as lock_file:

tests/test_platforms.py

@@ -18,6 +18,10 @@ def test_detect_platform_recognizes_windows():
     assert detect_platform(system_name="Windows", release="10", env={}) == "windows"
 
 
+def test_detect_platform_recognizes_win32_alias():
+    assert detect_platform(system_name="win32", release="10", env={}) == "windows"
+
+
 def test_windows_capabilities_disable_swarm_mailbox_and_sandbox():
     capabilities = get_platform_capabilities("windows")
     assert capabilities.supports_native_windows_shell is True

tests/test_swarm/test_lockfile.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import builtins
 from contextlib import contextmanager
 from pathlib import Path
 
@@ -45,6 +46,36 @@ def test_exclusive_file_lock_rejects_unknown_platform(tmp_path: Path):
             pass
 
 
+def test_posix_lock_reports_unavailable_when_fcntl_missing(monkeypatch, tmp_path: Path):
+    real_import = builtins.__import__
+
+    def fake_import(name, *args, **kwargs):
+        if name == "fcntl":
+            raise ImportError("missing fcntl")
+        return real_import(name, *args, **kwargs)
+
+    monkeypatch.setattr(builtins, "__import__", fake_import)
+
+    with pytest.raises(lockfile.SwarmLockUnavailableError, match="fcntl not available"):
+        with file_lock._exclusive_posix_lock(tmp_path / "posix.lock"):
+            pass
+
+
+def test_windows_lock_reports_unavailable_when_msvcrt_missing(monkeypatch, tmp_path: Path):
+    real_import = builtins.__import__
+
+    def fake_import(name, *args, **kwargs):
+        if name == "msvcrt":
+            raise ImportError("missing msvcrt")
+        return real_import(name, *args, **kwargs)
+
+    monkeypatch.setattr(builtins, "__import__", fake_import)
+
+    with pytest.raises(lockfile.SwarmLockUnavailableError, match="msvcrt not available"):
+        with file_lock._exclusive_windows_lock(tmp_path / "windows.lock"):
+            pass
+
+
 def test_swarm_lockfile_shim_re_exports_public_api():
     """Existing callers importing from ``swarm.lockfile`` must keep working."""
     assert lockfile.exclusive_file_lock is file_lock.exclusive_file_lock