mypy doesn't seem to detect this package

[d33tah]

Consider the following test file:

import boto3
from boto3_type_annotations.s3 import Bucket
bucket: Bucket = boto3.resource("s3").Bucket('asd')

And the following Dockerfile:

FROM python:3.7
RUN pip install boto3 boto3_type_annotations mypy
ADD ./a.py a.py
RUN mypy a.py

Here's what happens when I try to run it:

> sudo docker build . 
Sending build context to Docker daemon  3.072kB
Step 1/4 : FROM python:3.7
 ---> 023b89039ba4
Step 2/4 : RUN pip install boto3 boto3_type_annotations mypy
 ---> Using cache
 ---> f3145ded7f54
Step 3/4 : ADD ./a.py a.py
 ---> Using cache
 ---> d90f377d6b3e
Step 4/4 : RUN mypy a.py
 ---> Running in 6e8e8b383b62
a.py:1: error: No library stub file for module 'boto3'
a.py:1: note: (Stub files are from https://github.com/python/typeshed)
a.py:2: error: Cannot find module named 'boto3_type_annotations.s3'
a.py:2: note: See https://mypy.readthedocs.io/en/latest/running_mypy.html#missing-imports
Found 2 errors in 1 file (checked 1 source file)
The command '/bin/sh -c mypy a.py' returned a non-zero code: 1

Is this intentional that this package doesn't seem to work with mypy, or am I doing something wrong?

[ethanhs]

It looks like the package is missing a PEP 561 py.typed file (see https://mypy.readthedocs.io/en/latest/installed_packages.html#making-pep-561-compatible-packages).

[d33tah]

@ethanhs thanks! Not sure if I understand the documentation correctly though - does the py.typed file have to have any specific contents, or is it enough for it to be empty?

[ethanhs]

@d33tah empty is fine!

[vemel]

Just added a PR. Works great.

Thank you, guys!

[vemel]

I created a fork mypy-boto3 that supports mypy.
Some extra features:

• mypy compatibility as a main goal
• real type annotations. With boto3 naming style string annotations do not work
• subresources are included
• modularity, so you can install only services you use with or without docs
• full boto3 docs included and cleaned up
• black-formatted source code for easier reading

I welcome any feedback. Also, if someone can help with adding typing for return values and dict arguments - that would be great!