assert_raises.py

from typing import Type, Iterator
import contextlib


@contextlib.contextmanager
def assert_raises(expected: Type[Exception]) -> Iterator:
    try:
        yield
    except Exception as e:
        assert isinstance(e, expected), (
            f"Raised {type(e).__name__} instead of "
            f"{expected.__name__}"
        )
    else:
        raise AssertionError(
            f"{expected.__name__} was not raised")