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• ✅ login: wooyoung294 / name: 우영 (b7a51e4, 9c46a64, 62cc0bf, 5f153e3, 2482d3c)

Could you share an example of the incoming JSON that had \x89PNG\r\n\x1a\n\x00\x00\x00IHDR as your attached case?

Could you share an example of the incoming JSON that had \x89PNG\r\n\x1a\n\x00\x00\x00IHDR as your attached case?

@KazuCocoa @mykola-mokhnach Thanks for the review!

When you read a PNG in "rb" mode you get raw bytes like

b'\x89PNG\r\n\x1a\n\x00\x00\x00\rIHDR\x00\...

so "_adjust_image_payload" raises UnicodeDecodeError

def _adjust_image_payload(payload: Union[str,bytes]) -> str:
    return payload if isinstance(payload, str) else payload.decode('utf-8')

def test_non_utf8_payload_bytes_raise_unicode_decode_error():
    # i used https://png.pngtree.com/png-vector/20190411/ourmid/pngtree-vector-business-men-icon-png-image_925963.jpg
    path = "your.png"

    png_img = open(path, "rb").read()

    print(png_img,"\n") # b'\x89PNG\r\n\x1a\n\x00\x00\x00\rIHDR\x00\....
    print("path_type:",type(png_img),"\n") # <class 'bytes'>
    print(isinstance(png_img, bytes),"\n") # True

    _adjust_image_payload(png_img)

And I guess the line

data = utils.dump_json(param) in "def excute" does JSON serialization, so i modified it this way

def execute(self, command, params):
        """Send a command to the remote server.

        Any path substitutions required for the URL mapped to the command should be
        included in the command parameters.

        :Args:
         - command - A string specifying the command to execute.
         - params - A dictionary of named parameters to send with the command as
           its JSON payload.
        """
        command_info = self._commands.get(command) or self.extra_commands.get(command)
        ...
        data = utils.dump_json(params)

Thank you for taking the time to read through this long note.
I really appreciate all your work on appium-python-client, which I use a lot.
If this PR is off track or not appropriate, please feel free to close it.

Got it, thanks. We expect to get a base64-encoded string as the input. For example, match_images_features expects:

        Args:
            base64_image1: base64-encoded content of the first image
            base64_image2: base64-encoded content of the second image

e.g.
https://github.com/wooyoung294/python-client/blob/5f153e39caa5dba934ff39879f5c18f3ff248656/appium/webdriver/extensions/images_comparison.py#L37C1-L39C70

https://appium.github.io/python-client-sphinx/webdriver.extensions.html#webdriver.extensions.images_comparison.ImagesComparison.match_images_features

What we may do is to show a customized error message if UnicodeDecodeError pops up to help users figure out the issue, e.g.

try:
    return payload if isinstance(payload, str) else payload.decode('utf-8')
except UnicodeDecodeError as e:
    raise ValueError('The image payload cannot be serialized to a string. Make sure to base64-encode it first') from e

Thanks for guide and feedback!!

Applied the suggestion—now raising a helpful ValueError on UnicodeDecodeError

https://github.com/appium/python-client/actions/runs/17635493188/job/50111937540?pr=1172

Please apply formatting to pass unit tests (make format)