## Summary We currently perform a subtyping check instead of the intended subclass check (and the subtyping check is confusingly named `is_subclass_of`). This showed up in https://github.com/astral-sh/ruff/pull/21070.
Markdown files within the mdtest/ subdirectory are tests of type inference and type checking;
executed by the tests/mdtest.rs integration test.
See crates/ty_test/README.md for documentation of this test format.