Build the handler test's address list without a shared mutable default 🟪

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

tests/applications/sharepoint_renamer/test_handler.py

@@ -14,7 +14,7 @@ from collections.abc import Generator, Iterator
 from contextlib import contextmanager
 from dataclasses import dataclass, field
 from pathlib import Path
-from typing import Any, Callable, cast
+from typing import Any, Callable, Optional, cast
 from uuid import UUID
 
 import pytest
@@ -122,12 +122,14 @@ def _install(
     tmp_path: Path,
     sharepoint: FakeSharepoint,
     *,
-    rows: list[tuple[str, str, str]] = [(UPRN, ADDRESS, POSTCODE)],
+    rows: Optional[list[tuple[str, str, str]]] = None,
 ) -> None:
     """Point the handler at the fake SharePoint and a small address list, and
     configure the site the tests target."""
     import applications.sharepoint_renamer.handler as module
 
+    rows = rows if rows is not None else [(UPRN, ADDRESS, POSTCODE)]
+
     monkeypatch.setenv(f"{SITE}_SHAREPOINT_ID", "test-site-id")
 
     def client_for(_site: DomnaSites) -> FakeSharepoint: