Add test without members

Author: sterliakov

test-data/unit/check-selftype.test

@@ -2351,10 +2351,30 @@ reveal_type(gc.test())  # N: Revealed type is "builtins.list[__main__.D2]"
 from enum import Enum
 from typing import Self
 
+# This enum has members and so is implicitly final.
+# Foo and Self are interchangeable within the class.
 class Foo(Enum):
     A = 1
 
     @classmethod
-    def foo(self) -> Self:
+    def foo(cls) -> Self:
         return Foo.A
+
+    @classmethod
+    def foo2(cls) -> Self:
+        return cls.bar()
+
+    @classmethod
+    def bar(cls) -> Foo:
+        ...
+
+# This enum is empty and should not be assignable to Self
+class Bar(Enum):
+    @classmethod
+    def foo(cls) -> Self:
+        return cls.bar()  # E: Incompatible return value type (got "Bar", expected "Self")
+
+    @classmethod
+    def bar(cls) -> Bar:
+        ...
 [builtins fixtures/classmethod.pyi]