test_nntplib: sporadic failures, test_article_head_body()

@vstinner

BPO	19613
Nosy	@vstinner, @mcepl, @berkerpeksag, @vadmium, @koobs
Files	koobs-freebsd-10-python-3x-build-4682.txt ending-dot.patch ending-dot.v2.patch

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2013-11-15.17:30:45.877>
labels = ['type-bug', 'tests']
title = 'test_nntplib: sporadic failures, test_article_head_body()'
updated_at = <Date 2020-05-22.21:28:47.631>
user = 'https://github.com/vstinner'

bugs.python.org fields:

activity = <Date 2020-05-22.21:28:47.631>
actor = 'chris.jerdonek'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Tests']
creation = <Date 2013-11-15.17:30:45.877>
creator = 'vstinner'
dependencies = []
files = ['43901', '43903', '43905']
hgrepos = []
issue_num = 19613
keywords = ['patch', 'buildbot']
message_count = 19.0
messages = ['202961', '224475', '224476', '224481', '245538', '268972', '271423', '271426', '271428', '271429', '297134', '297529', '306936', '325829', '325921', '325923', '325924', '343039', '369649']
nosy_count = 5.0
nosy_names = ['vstinner', 'mcepl', 'berker.peksag', 'martin.panter', 'koobs']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue19613'
versions = ['Python 3.5', 'Python 3.6']

http://buildbot.python.org/all/builders/AMD64%20Ubuntu%20LTS%203.x/builds/3024/steps/test/logs/stdio

======================================================================
ERROR: test_article_head_body (test.test_nntplib.NetworkedNNTP_SSLTests)
----------------------------------------------------------------------

Traceback (most recent call last):
  File "/opt/python/3.x.langa-ubuntu/build/Lib/test/test_nntplib.py", line 251, in wrapped
    meth(self)
  File "/opt/python/3.x.langa-ubuntu/build/Lib/test/test_nntplib.py", line 178, in test_article_head_body
    self.check_article_resp(resp, body, art_num)
  File "/opt/python/3.x.langa-ubuntu/build/Lib/test/test_nntplib.py", line 158, in check_article_resp
    self.assertNotIn(article.lines[-1], (b".", b".\n", b".\r\n"))
IndexError: list index out of range

(...)
Re-running failed tests in verbose mode
Re-running test 'test_nntplib' in verbose mode
(...)
test_article_head_body (test.test_nntplib.NetworkedNNTPTests) ... ok

The last five builds have been successful so can this be closed as "out of date"?

The last five builds have been successful so can this be closed as "out of date"?

Really? I saw a lot of test_nntplib failures this week, on Windows buildbots for example.

Well, it's not exactly the same error, but it's still "sporadic failure" of test_nntp. Example:

http://buildbot.python.org/all/builders/x86%20Windows7%203.x/builds/8578/steps/test/logs/stdio

======================================================================
ERROR: test_zlogin (test.test_nntplib.NetworkedNNTPTests)
----------------------------------------------------------------------

Traceback (most recent call last):
  File "D:\cygwin\home\db3l\buildarea\3.x.bolen-windows7\build\lib\test\test_nntplib.py", line 251, in wrapped
    meth(self)
  File "D:\cygwin\home\db3l\buildarea\3.x.bolen-windows7\build\lib\test\test_nntplib.py", line 229, in test_zlogin
    user=baduser, password=badpw, usenetrc=False)
  File "D:\cygwin\home\db3l\buildarea\3.x.bolen-windows7\build\lib\unittest\case.py", line 704, in assertRaises
    return context.handle('assertRaises', callableObj, args, kwargs)
  File "D:\cygwin\home\db3l\buildarea\3.x.bolen-windows7\build\lib\unittest\case.py", line 162, in handle
    callable_obj(*args, **kwargs)
  File "D:\cygwin\home\db3l\buildarea\3.x.bolen-windows7\build\lib\nntplib.py", line 963, in login
    resp = self._shortcmd('authinfo user ' + user)
  File "D:\cygwin\home\db3l\buildarea\3.x.bolen-windows7\build\lib\nntplib.py", line 512, in _shortcmd
    return self._getresp()
  File "D:\cygwin\home\db3l\buildarea\3.x.bolen-windows7\build\lib\nntplib.py", line 450, in _getresp
    resp = self._getline()
  File "D:\cygwin\home\db3l\buildarea\3.x.bolen-windows7\build\lib\nntplib.py", line 433, in _getline
    line = self.file.readline(_MAXLINE +1)
  File "D:\cygwin\home\db3l\buildarea\3.x.bolen-windows7\build\lib\socket.py", line 514, in readinto
    raise OSError("cannot read from timed out object")
OSError: cannot read from timed out object

The timed out case seems to be similar to bpo-19756.

I presume the original report was due to testing when the server happened to return an article with an empty body. The failing test is

# XXX this could exceptionally happen...
self.assertNotIn(article.lines[-1], (b".", b".\n", b".\r\n"))

The test code already admits that what it is testing cannot be guaranteed (an article body could end with a full stop). And we have found another case where the test is not valid (an article with zero lines). I say remove this part of the test, at least when testing the article() and body() methods.

This just failed on 3.x (default) on koobs-freebsd{9,10} bots:

======================================================================
FAIL: test_article_head_body (test.test_nntplib.NetworkedNNTP_SSLTests)
----------------------------------------------------------------------

Traceback (most recent call last):
  File "/usr/home/buildbot/python/3.x.koobs-freebsd10/build/Lib/test/test_nntplib.py", line 240, in wrapped
    meth(self)
  File "/usr/home/buildbot/python/3.x.koobs-freebsd10/build/Lib/test/test_nntplib.py", line 185, in test_article_head_body
    self.check_article_resp(resp, body, art_num)
  File "/usr/home/buildbot/python/3.x.koobs-freebsd10/build/Lib/test/test_nntplib.py", line 165, in check_article_resp
    self.assertNotIn(article.lines[-1], (b".", b".\n", b".\r\n"))
AssertionError: b'.' unexpectedly found in (b'.', b'.\n', b'.\r\n')

Full log attached

A few other buildbots shared this failure. It would be nice to see what the article is that is causing the failure, but I’m fairly confident we should just remove this part of the test.

I played with the server and group that is apparently used in the test:

>>> server = NNTP_SSL("nntp.aioe.org")
>>> [_, _, first, last, _] = server.group("fr.comp.lang.python")
>>> first
2900
>>> last
2915
>>> server.body(last)[1].lines[-1]
b''
>>> server.body(first)[1].lines[-1]
b'Merci'
>>> server.body(last - 1)[1].lines[-1]
b'Kevin'

I tried all articles from 2900–2915, and none of them end with a dot on its own line, so I don’t actually know what caused the failure.

However looking again at the _getlongresp() implementation, I cannot imagine how the test failure can occur except for a genuine body that ends with a dot on its own line (encoded as b".." and then converted to b"."). Here is a quick patch to alter the test cases.

This version actually works :P

@martin

Sorry, I lost track of this issue. What is the status?

@martin: Do you want to convert your latest patch into a PR?

It looks like I was fairly confident about my patch, but it was all theoretical and I was never able to analyze the failure myself.

Sorry but I am unlikely to spend much time on this or open a pull request any time soon.

Victor opened bpo-32128 with the same complaint. I think I found the offending article:

>>> server = NNTP_SSL("nntp.aioe.org")
>>> [response, count, first, last, name] = server.group("comp.lang.python")
>>> last
199267
>>> pprint(server.article(199265)[1].lines)
[. . .
 b'Date: Fri, 24 Nov 2017 15:44:26 -0800 (PST)',
 . . .
 b'Message-ID: <[email protected]>',
 b'Subject: Re: Python loop and web server (bottle) in the same script (Posting',
 b'     On Python-List Prohibited)',
 . . .
 b'Content-Transfer-Encoding: quoted-printable',
 . . .
 b'If processing is I/O bound and not CPU bound, then asyncio should work fine=',
 b'.']

The body uses Quoted-printable encoding, and the previous line ends with an equals sign “=”, meaning a soft line break. So the full stop is on its own because the encoder didn’t want to fit it on the previous line. This is valid (albeit quirky) encoding, and not a problem with the NNTP library.

I suggest to close the issue since the bug didn't show up recently.

The test_article_head_body test is now skipped unconditionally:

@unittest.skipIf(True, "FIXME: see bpo-32128")

I don't think we should close this issue without re-enabling that test.

I don't think we should close this issue without re-enabling that test.

The fact is that nobody cares of test_nntplib: this issue is open for 5 years. I don't see how leaving the issue open which helps. It's fine to skip a test if nobody is available to fix it.

Well, no one is going to notice it if we close this issue. I don't see why the age of the issue matters here. We close issues when we fix them. It may take 20 minutes, 5 years or a decade.

I understand closing an issue as "out of date" when we couldn't find the root of the problem, but in this case the problem is obvious and there is already a patch that tries to fix it.

@vstinner

Could anybody make a PR from these patches? @vstinner, would you make me a review if I do it?

See also: https://bugs.python.org/issue40735 (test_with_statement)

I think we can close this old issue because the nntplib module is deprecated in 3.11 and set for removal in 3.13.

See PEP 594 – Removing dead batteries from the standard library and #91217.

@mcepl

I think we can close this old issue because the nntplib module is deprecated in 3.11 and set for removal in 3.13.

See PEP 594 – Removing dead batteries from the standard library and #91217.

Cc. @mcepl, @berkerpeksag, @vadmium, @koobs

Well, yes, see my comment before. With a little bit of help, I would be willing to take over nntplib as a separate module. Especially if with this PR it could became less dependent on the external servers.

Here's some Git tips on how to grab files with history:

https://discuss.python.org/t/pep-594-take-2-removing-dead-batteries-from-the-standard-library/13508/34?u=hugovk

Used for https://pypi.org/project/legacy-cgi/ / https://github.com/jackrosenthal/python-cgi

I did that already when creating https://git.sr.ht/~mcepl/nntplib

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test_nntplib: sporadic failures, test_article_head_body() #63812

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test_nntplib: sporadic failures, test_article_head_body() #63812

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vstinner commented on Nov 15, 2013

BreamoreBoy commented on Aug 1, 2014

vstinner commented on Aug 1, 2014

vstinner commented on Aug 1, 2014

vadmium commented on Jun 20, 2015

vadmium commented on Jun 21, 2016

koobs commented on Jul 27, 2016

vadmium commented on Jul 27, 2016

vadmium commented on Jul 27, 2016

vadmium commented on Jul 27, 2016

vstinner commented on Jun 28, 2017

vadmium commented on Jul 3, 2017

vadmium commented on Nov 25, 2017

vstinner commented on Sep 19, 2018

berkerpeksag commented on Sep 20, 2018

vstinner commented on Sep 20, 2018

berkerpeksag commented on Sep 20, 2018

mcepl commented on May 21, 2019

cjerdonek commented on May 22, 2020

hugovk commented on Apr 11, 2022

AlexWaygood commented on Apr 12, 2022

mcepl commented on Apr 12, 2022

hugovk commented on Apr 12, 2022

mcepl commented on Apr 12, 2022

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