test

Author: hauntsaninja

test-data/unit/check-narrowing.test

@@ -2714,7 +2714,14 @@ reveal_type(t.foo)  # N: Revealed type is "__main__.C"
 [builtins fixtures/property.pyi]
 
 [case testNarrowingNotImplemented]
+# flags: --python-version 3.13
 from __future__ import annotations
+import types
+
+def foo(x: types.NotImplementedType | str):
+    if x is not NotImplemented:
+        reveal_type(x)  # N: Revealed type is "builtins.str"
+
 from typing_extensions import Self
 
 class X:

test-data/unit/lib-stub/types.pyi

@@ -19,3 +19,5 @@ if sys.version_info >= (3, 10):
 
     class UnionType:
         def __or__(self, x) -> UnionType: ...
+
+    class NotImplementedType: ...