Message 322348 - Python tracker (original) (raw)

I have the following code that creates a simple email message with a) a pure-ASCII subject, b) non-ASCII subject (I made it into a unittest):

import email.generator import email.policy from email.mime.multipart import MIMEMultipart from email.mime.text import MIMEText from unittest import TestCase

def create_message(subject, sender, recipients, body): msg = MIMEMultipart() msg.set_charset('utf-8') msg.policy = email.policy.SMTP msg.attach(MIMEText(body, 'html')) msg['Subject'] = subject msg['From'] = sender msg['To'] = ';'.join(recipients) return msg

class TestEmailMessage(TestCase): def _make_message(self, subject): return create_message( subject=subject, sender='me@site.com', recipients=['me@site.com'], body='Some text', )

def test_ascii_message_no_len_limit(self):
    # very long subject consisting of a single word
    subject = 'Q' * 100
    msg = self._make_message(subject)
    self.assertTrue(str(msg))

def test_non_ascii_message_no_len_limit(self):
    # very long subject consisting of a single word
    subject = 'Ц' * 100
    msg = self._make_message(subject)
    self.assertTrue(str(msg))

The ASCII one passes, while the non-ASCII version fails with the following exception:

Traceback (most recent call last): File "/home/grigory/.pyenv/versions/3.6.4/lib/python3.6/unittest/case.py", line 59, in testPartExecutor yield File "/home/grigory/.pyenv/versions/3.6.4/lib/python3.6/unittest/case.py", line 605, in run testMethod() File "/home/grigory/PycharmProjects/smtptest/test_message.py", line 36, in test_non_ascii_message_no_len_limit self.assertTrue(str(msg)) File "/home/grigory/.pyenv/versions/3.6.4/lib/python3.6/email/message.py", line 135, in str return self.as_string() File "/home/grigory/.pyenv/versions/3.6.4/lib/python3.6/email/message.py", line 158, in as_string g.flatten(self, unixfrom=unixfrom) File "/home/grigory/.pyenv/versions/3.6.4/lib/python3.6/email/generator.py", line 116, in flatten self._write(msg) File "/home/grigory/.pyenv/versions/3.6.4/lib/python3.6/email/generator.py", line 195, in _write self._write_headers(msg) File "/home/grigory/.pyenv/versions/3.6.4/lib/python3.6/email/generator.py", line 222, in _write_headers self.write(self.policy.fold(h, v)) File "/home/grigory/.pyenv/versions/3.6.4/lib/python3.6/email/policy.py", line 183, in fold return self._fold(name, value, refold_binary=True) File "/home/grigory/.pyenv/versions/3.6.4/lib/python3.6/email/policy.py", line 205, in _fold return value.fold(policy=self) File "/home/grigory/.pyenv/versions/3.6.4/lib/python3.6/email/headerregistry.py", line 258, in fold return header.fold(policy=policy) File "/home/grigory/.pyenv/versions/3.6.4/lib/python3.6/email/_header_value_parser.py", line 144, in fold return _refold_parse_tree(self, policy=policy) File "/home/grigory/.pyenv/versions/3.6.4/lib/python3.6/email/_header_value_parser.py", line 2645, in _refold_parse_tree part.ew_combine_allowed, charset) File "/home/grigory/.pyenv/versions/3.6.4/lib/python3.6/email/_header_value_parser.py", line 2722, in _fold_as_ew first_part = to_encode[:text_space] TypeError: slice indices must be integers or None or have an index method

The problem is that _fold_as_ew treats maxlen as an integer, but it can also have inf and None as valid values. In my case it's inf, but None can also get there if the HTTP email policy is used and its max_line_length value is not overridden when serializing. I am supposing that the correct behavior in both of these cases should be no wrapping at all. And/or maybe one of these (inf & None) should be converted to the other at some point, so only one special case has to handled in the low-level code

This behavior is new in Python 3.6. It works in 3.5. Also fails in 3.7 and 3.8