[py] Fix type hints and docstring

[M1troll]

Hello!

Description

I found that get_attribute method in webelement in docstring says that method can return None, but type hint is only as a string. I ran into an unexpected error calling a string method on an NoneType-object.

I also saw that docstring in location_once_scrolled_into_view property of webelement contains an incorrect description of value returned when element is not visible.

Motivation and Context

This will help you avoid unexpected errors that may be caught by typecheckers (e.g. mypy).

Reproduce

You need install selenium and mypy:

pip install selenium mypy

Code example:

from selenium import webdriver
from selenium.webdriver.common.by import By

URL = "https://www.w3schools.com/css/tryit.asp?filename=trycss_display_none"

driver = webdriver.Chrome('/usr/sbin/chromedriver')
driver.get(URL)
driver.find_element(By.ID, "accept-choices").click()

hidden_element = driver.find_element(By.CLASS_NAME, "hidden")
hidden_element.get_attribute("class").strip()

Now if we run mypy . we won't see any errors:

But after fixing type hint, mypy will give us an error:

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have read the contributing document.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[CLAassistant]

All committers have signed the CLA.

[diemol]

I also saw that docstring in location_once_scrolled_into_view property of webelement contains an incorrect description of value returned when element is not visible.

Was this with Chrome and Firefox?

[M1troll]

Yes, I checked it in Chrome and Firefox
If element is not visible method returns {"x": 0, "y": 0}, not None

[diemol]

Thank you, @M1troll!

[codecov-commenter]

Codecov Report

Patch and project coverage have no change.

Comparison is base (f8b7a1d) 54.83% compared to head (d8a06ec) 54.83%.

❗ Current head d8a06ec differs from pull request most recent head 5f80221. Consider uploading reports for the commit 5f80221 to get more accurate results

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Additional details and impacted files

@@           Coverage Diff           @@
##            trunk   #12067   +/-   ##
=======================================
  Coverage   54.83%   54.83%           
=======================================
  Files          86       86           
  Lines        5730     5730           
  Branches      233      233           
=======================================
  Hits         3142     3142           
  Misses       2355     2355           
  Partials      233      233           

Impacted Files	Coverage Δ
py/selenium/webdriver/remote/webelement.py	35.59% <0.00%> (ø)

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.

[diemol]

Seems the linter is failing?

[M1troll]

You're right, but locally all linters run successfully, strange..
Can we rerun this check?

[diemol]

Not sure what the difference is, but the command used is TOXENV=linting-check tox -c py/tox.ini

[M1troll]

With this command everything passing too 🥲

[diemol]

I can see the same error, I started an environment in GitPod:

• https://gitpod.io/#https://github.com/SeleniumHQ/selenium/pull/12067
• Opened a terminal and did pip install tox==2.4.1
• Executed TOXENV=linting-check tox -c py/tox.ini

I also checked out the PR locally and got the same:

[M1troll]

@diemol
It looks like I found reason for the fall of linters - docformatter moved part of docstring to line above.
Can you approval workflow to run actions?

[M1troll]

@diemol
Linters have been passed 🎉

[diemol]

Thank you, @M1troll!