more tests never hurt

tests/pep570.pyi

@@ -1,18 +1,22 @@
 # See https://peps.python.org/pep-0484/#positional-only-arguments
 # for the full details on which arguments using the older syntax should/shouldn't
 # be considered positional-only arguments by type checkers.
-
-def no_args() -> None: ...
+from typing import Self
 
 def bad(__x: int) -> None: ...  # Y063 Use PEP-570 syntax to indicate positional-only arguments
 def also_bad(__x: int, __y: str) -> None: ...  # Y063 Use PEP-570 syntax to indicate positional-only arguments
 def still_bad(__x_: int) -> None: ...  # Y063 Use PEP-570 syntax to indicate positional-only arguments
 
+def no_args() -> None: ...
 def okay(__x__: int) -> None: ...
 # The first argument isn't positional-only, so logically the second can't be either:
 def also_okay(x: int, __y: str) -> None: ...
 def fine(x: bytes, /) -> None: ...
 def no_idea_why_youd_do_this(__x: int, /, __y: str) -> None: ...
+def cool(_x__: int) -> None: ...
+def also_cool(x__: int) -> None: ...
+def unclear_from_pep_484_if_this_is_positional_or_not(__: str) -> None: ...
+def _(_: int) -> None: ...
 
 class Foo:
     def bad(__self) -> None: ...  # Y063 Use PEP-570 syntax to indicate positional-only arguments
@@ -22,13 +26,39 @@ class Foo:
     def still_bad(self, __x_: int) -> None: ...  # Y063 Use PEP-570 syntax to indicate positional-only arguments
     @staticmethod
     def this_is_bad_too(__x: int) -> None: ...  # Y063 Use PEP-570 syntax to indicate positional-only arguments
+    @classmethod
+    def not_good(cls, __foo: int) -> None: ...  # Y063 Use PEP-570 syntax to indicate positional-only arguments
 
     # The first non-self argument isn't positional-only, so logically the second can't be either:
     def okay1(self, x: int, __y: int) -> None: ...
     # Same here:
     @staticmethod
     def okay2(x: int, __y_: int) -> None: ...
+    @staticmethod
+    def no_args() -> int: ...
     def okay3(__self__, __x__: int, __y: str) -> None: ...
     def okay4(self, /) -> None: ...
     def okay5(self, x: int, /) -> None: ...
     def okay6(__self, /) -> None: ...
+    def cool(_self__: int) -> None: ...
+    def also_cool(self__: int) -> None: ...
+    def unclear_from_pep_484_if_this_is_positional_or_not(__: str) -> None: ...
+    def _(_: int) -> None: ...
+    @classmethod
+    def fine(cls, foo: int, /) -> None: ...
+
+class Metaclass(type):
+    @classmethod
+    def __new__(mcls, __name: str, __bases: tuple[type, ...], __namespace: dict, **kwds) -> Self: ...  # Y063 Use PEP-570 syntax to indicate positional-only arguments
+
+class Metaclass2(type):
+    @classmethod
+    def __new__(metacls, __name: str, __bases: tuple[type, ...], __namespace: dict, **kwds) -> Self: ...  # Y063 Use PEP-570 syntax to indicate positional-only arguments
+
+class GoodMetaclass(type):
+    @classmethod
+    def __new__(mcls, name: str, bases: tuple[type, ...], namespace: dict, /, **kwds) -> Self: ...
+
+class GoodMetaclass2(type):
+    @classmethod
+    def __new__(metacls, name: str, bases: tuple[type, ...], namespace: dict, /, **kwds) -> Self: ...