I got good use of the run-time type checking of typeguard [0] when I recently invoked it via its pytest plugin [2]. For all code visited in the test suite, you get a failing test whenever an actual type differs from an annotated type.

[0]: https://github.com/agronholm/typeguard/

[1]: https://typeguard.readthedocs.io/en/latest/userguide.html#us...