Guard geo_service.init_geoip against repeated initialization

backend/tests/test_services/test_geo_service.py

@@ -48,6 +48,31 @@ def _make_session(response_json: dict[str, object], status: int = 200) -> MagicM
 async def clear_geo_cache() -> None:
     """Flush the module-level geo cache before every test."""
     await geo_service.clear_cache()
+    geo_service._geoip_reader = None
+    geo_service._geoip_initialized = False
+
+
+def test_init_geoip_is_startup_only(tmp_path) -> None:
+    """A second init_geoip() call raises when the reader was already loaded."""
+    path = tmp_path / "GeoLite2-Country.mmdb"
+    path.write_text("dummy")
+
+    with patch("geoip2.database.Reader", MagicMock(name="Reader")) as mock_reader:
+        geo_service.init_geoip(str(path))
+        assert geo_service._geoip_reader is not None
+        assert geo_service._geoip_initialized is True
+
+        with pytest.raises(RuntimeError, match="already initialised"):
+            geo_service.init_geoip(str(path))
+
+    assert mock_reader.call_count == 1
+
+
+def test_init_geoip_no_path_leaves_reader_uninitialised() -> None:
+    """No active reader is created when no path is supplied."""
+    geo_service.init_geoip("")
+    assert geo_service._geoip_reader is None
+    assert geo_service._geoip_initialized is False
 
 
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