App decorator methods (e.g., action, command) have incorrect return type annotation

[chrisbouchard]

Methods on App that are intended to be used as decorators have an incorrect return type annotation. E.g., for App.command,

def command(
    self,
    command: Union[str, Pattern],
    matchers: Optional[Sequence[Callable[..., bool]]] = None,
    middleware: Optional[Sequence[Union[Callable, Middleware]]] = None,
) -> Optional[Callable[..., Optional[BoltResponse]]]:

As written, this is actually the return type for the __call__ function (the function returned by command). I believe the actual return type annotation for this method should be

-> Callable[..., Optional[Callable[..., Optional[BoltResponse]]]]

I believe this same bug exists for all decorator methods. I've just used command as an example because it's the one I was using in my code.

Reproducible in:

pip freeze | grep slack
python --version
sw_vers && uname -v # or `ver`

The slack_bolt version

slack-bolt @ file:///home/chris/.cache/pypoetry/artifacts/07/a4/dc/0ff1b9
e40910182628c62f696f06a685006e9bbebde8e0fbbf8dc2aa6c/slack_bolt-1.9.0-py2
.py3-none-any.whl
slack-sdk @ file:///home/chris/.cache/pypoetry/artifacts/54/72/e4/1b7d076
acf9c2a6c8175154452e38c8cd43f48c7f2c987c804b32c8a8c/slack_sdk-3.10.1-py2.
py3-none-any.whl

The mypy version

mypy @ file:///home/chris/.cache/pypoetry/artifacts/36/49/09/f6ff69bf72a4
3d56fd882450780491cf84523aa3cb39b1d0e3f2c6c9a4/mypy-0.910-cp39-cp39-manyl
inux2010_x86_64.whl

Python runtime version

Python 3.9.6

OS info

(I ran uname -av because neither of the commands listened work on Fedora.)

Linux **** 5.13.12-200.fc34.x86_64 #1 SMP Wed Aug 18 13:27:18 UTC 2021 x86
_64 x86_64 x86_64 GNU/Linux

Steps to reproduce:

(Share the commands to run, source code, and project settings (e.g., setup.py))

1. Create an App instance called app.
2. Register a listener:

   app.command(COMMAND_NAME)(listener_function)

3. Run mypy on the code.

Expected result:

mypy returns no type errors.

Actual result:

mypy returns an error for the line registering the listener function.

error: "None" not callable

Requirements

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[seratch]

Hi @chrisbouchard, thanks for taking the time to report this issue! And you are right that those type hints are not correct. We'll fix this issue in the next release.

[chrisbouchard]

Thank you for addressing this so quickly!