How do __enter__ and __exit__ work in Python decorator classes?

the __exit__() method should accept information about exceptions that come up in the with: block. See here.

The following modification of your code works:

def __exit__(self, exc_type, exc_value, tb):
    if exc_type is not None:
        traceback.print_exception(exc_type, exc_value, tb)
        # return False # uncomment to pass exception through

    return True

Then you can try raising an exception in one of your with: blocks and it’ll be caught in __exit__().