fix(test): disable C++ extension in unit tests to prevent Windows hang

Unit tests create UdpTransport/TcpTransport objects that, when the C++
extension is present (e.g. in cibuildwheel), instantiate native transports
whose start() blocks on Windows. Add an autouse conftest fixture that
patches _load_extension to return None and clears the get_ext LRU cache,
ensuring unit tests always exercise the pure-Python path regardless of
whether the extension is installed.

Made-with: Cursor

Author: vtz

tests/unit/conftest.py

@@ -0,0 +1,22 @@
+"""Unit test configuration — force pure-Python path.
+
+Unit tests validate Python-level behaviour and must not depend on
+native transport I/O, which may block on some platforms (e.g. Windows).
+"""
+
+from __future__ import annotations
+
+from unittest.mock import patch
+
+import pytest
+
+from opensomeip._bridge import get_ext
+
+
+@pytest.fixture(autouse=True)
+def _no_native_ext() -> None:  # type: ignore[misc]
+    """Ensure ``get_ext()`` returns ``None`` for every unit test."""
+    get_ext.cache_clear()
+    with patch("opensomeip._bridge._load_extension", return_value=None):
+        yield  # type: ignore[misc]
+    get_ext.cache_clear()

tests/unit/test_coverage_gaps.py

@@ -231,7 +231,6 @@ def test_send_uses_source_endpoint_when_no_endpoint_or_remote(self) -> None:
         t._cpp = mock_cpp
         msg = Message(payload=b"test")
         msg.source_endpoint = Endpoint("192.168.1.1", 30490)
-        # Patch to_cpp_* when extension may be unavailable
         mock_cpp_msg = MagicMock()
         mock_cpp_ep = MagicMock()
         with (
@@ -256,10 +255,6 @@ def test_send_large_message_pure_python_path(self) -> None:
         tp = __import__("opensomeip.tp", fromlist=["TpManager"]).TpManager
         manager = tp(t, mtu=100)
         manager.start()
-        # With ext possibly available, we need to force pure-Python path.
-        # When ext is None, _cpp is None, so the else branch (lines 112-126) runs.
-        # When ext is available, the try block runs. To hit pure-Python path,
-        # we can patch _cpp to None.
         with patch.object(manager, "_cpp", None):
             msg = Message(
                 message_id=MessageId(0x1234, 0x0001),