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

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]:
            ...

appium.webdriver.WebDriver から調査を始め、継承された find_element と find_elements のシグネチャを確認します。再現可能なスニペットを mypy で実行し、その後、WebDriver のアノテーションによって Appium WebElement の戻り値型が生成され、報告された return-value エラーが解消されることを検証します。