fix UnknownCommandError

[KazuCocoa]

for #865

Still initial implementation.

[mykola-mokhnach]

could it be the server throws anything else other than UnknownMethodException in case of missing method?

[KazuCocoa]

UnknownMethodException is only raised by

python-client/appium/webdriver/webdriver.py

Lines 505 to 517 in a369b6f

	def assert_extension_exists(self, ext_name: str) -> 'WebDriver':
	"""
	Verifies if the given extension is not present in the list of absent extensions
	for the given driver instance.
	This API is designed for private usage.
	:param ext_name: extension name
	:return: self instance for chaining
	:raise UnknownMethodException: If the extension has been marked as absent once
	"""
	if ext_name in self._absent_extensions:
	raise UnknownMethodException()
	return self

. Serveeer only raised a general error, so python client handled it only as WebDriverException

[mykola-mokhnach]

This must be a bug in the Python client itself. I believe it does not properly map the exception raised by the server because this works as expected with Java

[KazuCocoa]

oh, then, i guess in selenium client side..? Quickly checked with ruby client. it also actually handled as Selenium::WebDriver::Error::UnknownCommandError. I'll take a look this weekend

[mykola-mokhnach]

No worries, I have already prepared a fix: #869

Thanks for pointing this out, I did not know it's so broken. Seems like the actual error handling code in selenium client has not been updated since ages and only supports responses in JWP format

[KazuCocoa]

thanks, gotcha. Then this pr is no longer needed

[mykola-mokhnach]

protocols must not contain method implementations

[KazuCocoa]

yea, i noticed the implementation was in webdriver.py