[🐛 Bug]: [py] Many type annotation errors need fixing

[cgoldberg]

Description

TLDR: Our use of type hints in the Python bindings needs some serious love.

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Static typing is optional in Python, and we make use of it in many places throughout the Python bindings code. Static typing is not enforced at runtime, but can be checked with tooling like Mypy.

We currently have a Mypy environment and set of type checking rules declared in our tox.ini configuration. You can run Mypy locally with:

tox -e py/tox.ini -e mypy

Running this produces a screen full of type errors and:

Found 120 errors in 30 files (checked 114 source files)

We currently run Mypy in a CI workflow, but we don't display the errors or fail the job when it hits errors, so they just go unnoticed.

To resolve this issue, we should:

• go through the codebase and fix all of the errors that Mypy finds
• update the CI job to fail when Mypy encounters errors to enforce no future regressions

Reproducible Code

tox -e py/tox.ini -e mypy

Debugging Logs

Found 120 errors in 30 files (checked 114 source files)

[selenium-ci]

This issue is looking for contributors.

Please comment below or reach out to us through our IRC/Slack/Matrix channels if you are interested.

[MohabASHRAF-byte]

Hello, can I work on this ?

[navin772]

@MohabASHRAF-byte yes, go ahead. We appreciate contributions from your side.

[MohabASHRAF-byte]

@navin772 Is there a communication channel other than GitHub?

[navin772]

@MohabASHRAF-byte Yes, we use slack, you can join here - https://inviter.co/seleniumhq

[cgoldberg]

@MohabASHRAF-byte thanks! Not only are there many Mypy errors, but many of the type annotations are using outdated classes and syntax. An easy way to update them is by using this:

https://github.com/asottile/pyupgrade

Run it across the whole codebase using Python 3.9 syntax.

Ping me here or on Slack if you have any questions.

[MohabASHRAF-byte]

@MohabASHRAF-byte thanks! Not only are there many Mypy errors, but many of the type annotations are using outdated classes and syntax. An easy way to update them is by using this:

https://github.com/asottile/pyupgrade

Run it across the whole codebase using Python 3.9 syntax.

Ping me here or on Slack if you have any questions.

ok, thank you, I will consider it, and I sent a request to join Slack.

[MarcelWilson]

I started attempting to do some mypy cleanup about a year ago and got frustrated by the lack of dependency setup in the project. Tox will install particular packages used for checking but those same packages aren't listed in the requirements.txt or in a requirements_dev.txt.

If that particular hurdle were removed I think we could get a little better traction.