mypy doesn't seem to enforce instance attributes Dict types

[fpagnoux]

I would expect the following snippet to raise an error when checked by mypy, yet nothing is detected.

class Test:
    def __init__(self):
        self.data: Dict[str, int] = {}

    def get(self, key) -> str:  # inconsistent with self.data type, should be int
        return self.data[key]

I'm using Python 3.7.0 and mypy 0.701
I'm still seeing the issue on master
I'm only using the flag ignore_missing_imports = True

Am I doing something wrong?

[ilevkivskyi]

This is a funny one. The problem is that you don't import Dict. Moreover __init__ doesn't have any annotations, so errors aren't reported there, see PEP 484.

You can use --disallow-untyped-defs to avoid such mistakes in future, or alternatively --warn-return-any to warn you when type checking passes because the thing you return is Any.