Fix lint and test

Author: yilinjuang

src/graphql/pyutils/path.py

@@ -2,15 +2,15 @@
 
 from __future__ import annotations
 
-from typing import Any, NamedTuple, Optional
+from typing import NamedTuple
 
 __all__ = ["Path"]
 
 
 class Path(NamedTuple):
     """A generic path of string or integer indices"""
 
-    prev: Optional[Path]
+    prev: Path | None
     """path with the previous indices"""
     key: str | int
     """current index in the path (string or integer)"""
@@ -25,7 +25,7 @@ def as_list(self) -> list[str | int]:
         """Return a list of the path keys."""
         flattened: list[str | int] = []
         append = flattened.append
-        curr: Path = self
+        curr: Path | None = self
         while curr:
             append(curr.key)
             curr = curr.prev

src/graphql/validation/rules/overlapping_fields_can_be_merged.py

@@ -38,8 +38,6 @@
     from typing_extensions import TypeAlias
 
 
-MYPY = False
-
 __all__ = ["OverlappingFieldsCanBeMergedRule"]
 
 

tests/execution/test_executor.py

@@ -308,9 +308,11 @@ def resolve_type(_val, _info, _type):
         prev, key, typename = path
         assert key == "l2"
         assert typename == "SomeObject"
+        assert prev is not None
         prev, key, typename = prev
         assert key == 0
         assert typename is None
+        assert prev is not None
         prev, key, typename = prev
         assert key == "l1"
         assert typename == "SomeQuery"