appium / appium/python-client

mypy error "Incompatible return value type" on webdriver.find_element

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Python
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Description

Mypy errors on the fact that appium.webdriver.WebDriver.find_element isn't overridden but indeed returns a different WebElement.

Reproducible Code
# no need to actually run this code, just send it through MyPy to see the error.

from appium.webdriver.common.appiumby import AppiumBy

from typing import TYPE_CHECKING

if TYPE_CHECKING:
    from appium.webdriver import Remote
    from appium.webdriver.webelement import WebElement

def find_element(driver: Remote) -> WebElement:
    # should get a mypy error on next line
    return driver.find_element(AppiumBy.ACCESSIBILITY_ID, "demo button")


def find_elements(driver: Remote) -> WebElement:
    # should get a mypy error on next line
    return driver.find_elements(AppiumBy.ACCESSIBILITY_ID, "demo confetti")
mypy output:
mypy .
screenpy_appium/target.py:89: error: Incompatible return value type (got "selenium.webdriver.remote.webelement.WebElement", expected "appium.webdriver.webelement.WebElement")  [return-value]
screenpy_appium/target.py:98: error: Incompatible return value type (got "list[selenium.webdriver.remote.webelement.WebElement]", expected "list[appium.webdriver.webelement.WebElement]")  [return-value]
Found 2 errors in 1 file (checked 35 source files)
Solution

Annotations need to be added to appium.webdriver.WebDriver

class WebDriver(
    webdriver.Remote,
    ...
):
    if TYPE_CHECKING:
        def find_element(self, by=By.ID, value: Optional[str] = None) -> MobileWebElement:
            ...
        def find_elements(self, by=By.ID, value: Optional[str] = None) -> list[MobileWebElement]:
            ...

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start at appium.webdriver.WebDriver and inspect its inherited find_element and find_elements signatures. Run the reproducible snippet through mypy, then verify that the WebDriver annotations produce Appium WebElement return types and the reported return-value errors disappear.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
mobile-dev
Issue type
Bug
Difficulty
2/5
Estimated time
1-3 hours
Activity status
Stale
Clarity
Clearly specified
Newbie friendliness
55/100

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