Encoding invalid characters

[adrianschlatter]

Trying to encode a character which is not supported by a codec will raise an exception (=> good). However, the error message is a bit misleading in some cases.

Example:

'ä'.encode('datamatrix.EDIFACT')

UnicodeEncodeError: 'ascii' codec can't encode character '\xe4' in position 0: ordinal not in range(128)
---------------------------------------------------------------------------
UnicodeEncodeError                        Traceback (most recent call last)
/InteractiveInput-1 in <module>
----> 1 'ä'.encode('datamatrix.EDIFACT')

~/Projects/ppf.datamatrix/src/ppf/datamatrix/codec_edifact.py in encode_to_edifact(msg)
     46     elif n_rest == 1:
     47         if len(msg) < 2:
---> 48             enc = (b'\xF0' + pack(msg.encode('ascii'), b'\x1F\x00\x00'))
     49         else:
     50             enc = (b'\xF0' +

UnicodeEncodeError: 'ascii' codec can't encode character '\xe4' in position 0: ordinal not in range(128)

Note that we are trying to encode in 'datamatrix.EDIFACT'. But the error message says there is a failure when encoding to 'ascii'. We should catch this exception and re-raise an exception that say 'ä' is an invalid datamatrix.EDIFACT character.

Similar things happen in other codecs.