fix:[FL-218][角色管理列表接口返回 500]

Co-authored-by: multica-agent <github@multica.ai>

api/tests/test_role_pagination_contract.py

@@ -7,6 +7,27 @@ def _role_row(index: int) -> dict[str, object]:
     return {"id": f"role-{index}", "code": f"role-{index}", "name": f"Role {index}"}
 
 
+class _EmptyRolePageRows:
+    def mappings(self):
+        return self
+
+    def all(self) -> list[dict[str, object]]:
+        return []
+
+
+class _RolePageCaptureDb:
+    def __init__(self) -> None:
+        self.calls: list[tuple[str, str, dict[str, object]]] = []
+
+    def scalar(self, stmt, params=None) -> int:
+        self.calls.append(("scalar", str(stmt), dict(params or {})))
+        return 0
+
+    def execute(self, stmt, params=None) -> _EmptyRolePageRows:
+        self.calls.append(("execute", str(stmt), dict(params or {})))
+        return _EmptyRolePageRows()
+
+
 def test_list_roles_returns_filtered_total_before_pagination(monkeypatch) -> None:
     captured: dict[str, object] = {}
 
@@ -51,3 +72,40 @@ def test_list_roles_with_menus_paginates_roles_only(monkeypatch) -> None:
     assert response.menus == []
     assert response.menus_total == 2
     assert captured == {"role_source": "modern", "keyword": None, "limit": 1, "offset": 1}
+
+
+def test_load_role_page_without_keyword_omits_nullable_keyword_predicate() -> None:
+    for role_source in ("legacy", "modern"):
+        db = _RolePageCaptureDb()
+
+        rows, total = service._load_role_page(db, role_source=role_source, keyword=None, limit=20, offset=0)
+
+        assert rows == []
+        assert total == 0
+        assert len(db.calls) == 2
+        for _, sql, params in db.calls:
+            assert ":keyword" not in sql
+            assert ":keyword IS NULL" not in sql
+            assert "removed_menu_codes" not in params
+
+
+def test_load_role_page_with_keyword_uses_normalized_like_filter() -> None:
+    role_predicates = {
+        "legacy": "LOWER(r.id) LIKE :keyword",
+        "modern": "LOWER(r.code) LIKE :keyword",
+    }
+    for role_source, role_predicate in role_predicates.items():
+        db = _RolePageCaptureDb()
+
+        rows, total = service._load_role_page(db, role_source=role_source, keyword=" Admin ", limit=20, offset=0)
+
+        assert rows == []
+        assert total == 0
+        assert len(db.calls) == 2
+        for _, sql, params in db.calls:
+            assert ":keyword IS NULL" not in sql
+            assert role_predicate in sql
+            assert "LOWER(r.name) LIKE :keyword" in sql
+            assert "LOWER(m.code) LIKE :keyword" in sql
+            assert params["keyword"] == "%admin%"
+            assert "removed_menu_codes" in params