add failing test

crates/ty_python_semantic/resources/mdtest/annotations/callable.md

@@ -407,4 +407,21 @@ def f_okay(c: Callable[[], None]):
             c.__qualname__ = "my_callable"  # okay
 ```
 
+## From a class
+
+### Subclasses should return themselves, not superclass
+
+```py
+from ty_extensions import into_callable
+
+class Base:
+    def __init__(self) -> None: pass
+
+class A(Base):
+    pass
+
+# revealed: () -> A
+reveal_type(into_callable(A))
+```
+
 [gradual form]: https://typing.python.org/en/latest/spec/glossary.html#term-gradual-form