fix: add pragma no cover to Protocol stubs and unreachable mock branch

Protocol stub methods (fetch_token, create_authorization_url,
ensure_active_token) have Ellipsis bodies that coverage flags as
uncovered branches because Protocol classes are never instantiated.
Mark them with pragma: no cover.

The fallback path in _mock_iterdir (returning original_iterdir when the
path does not contain "fake") is only reachable on Windows where
jsonschema lazily loads schemas during the test. On Linux/macOS jsonschema
loads schemas eagerly so the branch is never taken. Mark it accordingly.

Author: harsh543

src/mcp/client/auth/authlib_adapter.py

@@ -64,11 +64,11 @@ class _AsyncOAuth2ClientProtocol(Protocol):
     scope: str | None
     code_challenge_method: str
 
-    async def fetch_token(self, url: str, **kwargs: Any) -> dict[str, Any]: ...
+    async def fetch_token(self, url: str, **kwargs: Any) -> dict[str, Any]: ...  # pragma: no cover
 
-    def create_authorization_url(self, url: str, **kwargs: Any) -> tuple[str, str]: ...
+    def create_authorization_url(self, url: str, **kwargs: Any) -> tuple[str, str]: ...  # pragma: no cover
 
-    async def ensure_active_token(self, token: dict[str, Any]) -> None: ...
+    async def ensure_active_token(self, token: dict[str, Any]) -> None: ...  # pragma: no cover
 
 
 # ---------------------------------------------------------------------------

tests/test_examples.py

@@ -76,7 +76,7 @@ def _mock_iterdir(self: Path) -> object:
         # loading (which also calls Path.iterdir) is not affected on any platform.
         if "fake" in str(self):
             return mock_files
-        return original_iterdir(self)  # type: ignore[reportUnknownArgumentType]
+        return original_iterdir(self)  # pragma: no cover
 
     monkeypatch.setattr(Path, "iterdir", _mock_iterdir)
     monkeypatch.setattr(Path, "home", lambda: Path("/fake/home"))