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Title: regrtest: use backslashreplace error handler for stdout
Type: Stage:
Components: Tests, Unicode Versions: Python 3.1, Python 3.2
Status: closed Resolution: fixed
Dependencies: Superseder:
Assigned To: Nosy List: flox, ocean-city, pitrou, python-dev, vstinner
Priority: normal Keywords: patch

Created on 2010-04-26 10:43 by vstinner, last changed 2022-04-11 14:57 by admin. This issue is now closed.

File name Uploaded Description Edit
regrtest_stdout_backslashreplace.patch vstinner, 2010-04-26 10:43
regrtest_traceback_stderr-2.patch vstinner, 2010-04-30 22:45
regrtest_stdout_newline.patch vstinner, 2010-05-05 21:31
py3k_regrtest_newline.patch ocean-city, 2010-09-10 11:08
py3k_regrtest_newline_more.patch ocean-city, 2010-09-10 11:10
py3k_also_no_unicode_error_on_direct_test_run.patch ocean-city, 2010-10-12 00:24 review
Messages (21)
msg104212 - (view) Author: STINNER Victor (vstinner) * (Python committer) Date: 2010-04-26 10:43
If a test fails, regrtest writes the backtrace to sys.stdout. If the backtrace contains a non-ASCII characters, it's encoded using sys.stdout encoding.

In some conditions, sys.stdout is unable to encode some or all non-ASCII characters. Eg. if there is no locale set (empty environment or at least empty LANG variable value), sys.stdout.encoding="ascii".

If regrtest fails to display a test output (error backtrace), regrtest exits directly (don't execute next tests).

I propose to use backslashreplace error handler in sys.stdout, as done for sys.stderr to avoid this annoying issue.

Attached patch (for py3k) replace sys.stdout by a new file using backslashreplace, just before executing the tests.

I don't know if the issue concerns also Python2.
msg104223 - (view) Author: Antoine Pitrou (pitrou) * (Python committer) Date: 2010-04-26 11:30
A better resolution IMO would be to output tracebacks on stderr instead.
msg104229 - (view) Author: STINNER Victor (vstinner) * (Python committer) Date: 2010-04-26 12:47
> A better resolution IMO would be to output tracebacks on stderr instead.

Yeah, that sounds easier and safer. Attached patch writes the tracebacks to stderr.

I don't remember how to reproduce this issue :-/ I guess that stdout/stderr encoding should be ASCII (eg. LANG="") and the traceback (eg. the error message) should contain a non-ASCII character.
msg104231 - (view) Author: STINNER Victor (vstinner) * (Python committer) Date: 2010-04-26 12:49
Write to stderr instead of stdout might change buildbot output order.
msg104670 - (view) Author: STINNER Victor (vstinner) * (Python committer) Date: 2010-04-30 22:45
regrtest_traceback_stderr.patch	is not enough: support._run_suite() writes output to sys.stdout instead of sys.stderr. New version of the patch fixes that.
msg104773 - (view) Author: STINNER Victor (vstinner) * (Python committer) Date: 2010-05-02 09:38
Ok, let's try sys.stderr solution: commited in r80694 (py3k).

If it breaks buildbot outputs, I will revert it and try the second solution.
msg104783 - (view) Author: Antoine Pitrou (pitrou) * (Python committer) Date: 2010-05-02 11:08
Since it may reorder output, I think it's better revert the patch and try the other solution. However, I don't think you need to replace sys.stdout at all: just output the traceback more carefully.
msg104794 - (view) Author: STINNER Victor (vstinner) * (Python committer) Date: 2010-05-02 17:25
As "expected", the patch doesn't work: it randomize the output order :-(

I checked "sparc Ubuntu 3.x": the output order is correct. "test_xxx" lines are written to stdout, "FAIL: ..." + traceback are written to stderr, and the lines are written in the right order.

But it failed on "x86 Tiger 3.x" : Tiger 3.x/builds/130/steps/test/logs/stdio Tiger 3.x/builds/131/steps/test/logs/stdio

When a test is reexecuted in verbose mode, the output is written in red (why not, but it was not the case before my commit), and the stdout and stderr are in a "mixed".


antoine> just output the traceback more carefully.

Encode the traceback by hand would be possible, but it's more complex. A possible solution would be to write the output to a StringIO, encode unicode to bytes using the right encoding and backslashreplace error handler, and write the result to stdout. But I don't like buffering the output because the buildbot may hung for different reasons (search in the bug tracker for "test_multiprocessing" or "test_subprocess"...) and the buildbot master may consider the buildbot as dead (no new output since xxx seconds, whereas it's writing to a buffer).


I prefer my first simple idea: use backslashreplace error handler for stdout. Let's try: r80703. This commit reverts my previous commit, apply regrtest_stdout_backslashreplace.patch + a fix for multiprocessing mode ( -j ...).
msg104824 - (view) Author: STINNER Victor (vstinner) * (Python committer) Date: 2010-05-03 08:37
> Let's try: r80703

This one looks ok: the output order is kept and I didn't noticed anything special in the buildbot output.

Backported to 3.1 as r80711. Close the issue.
msg105087 - (view) Author: STINNER Victor (vstinner) * (Python committer) Date: 2010-05-05 21:31
Reopen: r80703 (and r80711) introduces a new bug: on Windows, there is an empty string between each line. It looks like a newline error.

replace_stdout() should set the newline argument to open(). But how can I get the newline attribute from sys.stdout? sys.stdout._writenl?

regrtest_stdout_newline.patch should fix the newline problem.
msg105180 - (view) Author: STINNER Victor (vstinner) * (Python committer) Date: 2010-05-07 00:59
I disabled my patch (replace_stdout function) on Windows until it gets fixed: r80905 (py3k) and r80906 (3.1)
msg116003 - (view) Author: Hirokazu Yamamoto (ocean-city) * (Python committer) Date: 2010-09-10 11:08
Hello. How about this patch? I just mimicked create_stdio() in
Python/pythonrun.c. (Mostly) Newlines looks correct as well as
python2.x. I tested this on windows.
msg116004 - (view) Author: Hirokazu Yamamoto (ocean-city) * (Python committer) Date: 2010-09-10 11:10
And here is more advanced (?) patch. More closer to Python/pythonrun.c
's implementaion.

I tried regrtest_stdout_newline.patch, but it doesn't work.
# AttributeError: '_io.TextIOWrapper' object has no attribute '_writenl'
msg118248 - (view) Author: Hirokazu Yamamoto (ocean-city) * (Python committer) Date: 2010-10-09 07:50
I noticed fd must be dup-ed before passing to
And I noticed direct test run like "py3k -m test.test_time"
still produces unicode error. (Maybe this is reasonable

I can confirm we can suppress the unicode error in such
case with newly attached patch. "py3k_also_no_unicode_error_on_direct_test_run.patch"
msg118253 - (view) Author: STINNER Victor (vstinner) * (Python committer) Date: 2010-10-09 08:16
py3k_also_no_unicode_error_on_direct_test_run.patch comes a little bit too late:

$ LANG= ./python Lib/test/ -v test_time
== CPython 3.2a2+ (py3k, Oct 8 2010, 01:40:20) [GCC 4.4.5 20100909 (prerelease)]
==   Linux-2.6.32-trunk-686-i686-with-debian-squeeze-sid little-endian
==   Traceback (most recent call last):
  File "Lib/test/", line 1478, in <module>
  File "Lib/test/", line 454, in main
    print("==  ", os.getcwd())
UnicodeEncodeError: 'ascii' codec can't encode characters in position 20-21: ordinal not in range(128)

My working directory is /home/haypo/prog/SVN/py3ké.
msg118256 - (view) Author: Hirokazu Yamamoto (ocean-city) * (Python committer) Date: 2010-10-09 08:58
Oops, sorry. I'll withdraw my last patch.
msg118395 - (view) Author: STINNER Victor (vstinner) * (Python committer) Date: 2010-10-11 21:50
> Oops, sorry. I'll withdraw my last patch.

Why? Your patch is useful to run a single test outside regrtest. But you should not remove the hack on, only keep your patch on unittest/ There are not exclusive.
msg118396 - (view) Author: Hirokazu Yamamoto (ocean-city) * (Python committer) Date: 2010-10-12 00:24
Thank you. I'll reattach the patch only for Lib/unittest/
msg123605 - (view) Author: Hirokazu Yamamoto (ocean-city) * (Python committer) Date: 2010-12-08 14:15
Well, can this go into Python3.2?
msg136813 - (view) Author: Roundup Robot (python-dev) (Python triager) Date: 2011-05-25 00:02
New changeset 8be9eaf5829f by Victor Stinner in branch 'default':
Issue #8533: regrtest replaces also sys.stdout on Windows
msg137330 - (view) Author: STINNER Victor (vstinner) * (Python committer) Date: 2011-05-30 21:09
The original issue (use backslashreplace for stdout in regrtest) is now fixed, and so I closed it.

@ocean-city: Can you please open a new issue for unittest? (for py3k_also_no_unicode_error_on_direct_test_run.patch)
Date User Action Args
2022-04-11 14:57:00adminsetgithub: 52779
2011-05-30 21:09:09vstinnersetstatus: open -> closed
resolution: fixed
messages: + msg137330
2011-05-25 00:02:57python-devsetnosy: + python-dev
messages: + msg136813
2010-12-08 14:15:48ocean-citysetmessages: + msg123605
2010-10-12 00:24:05ocean-citysetfiles: + py3k_also_no_unicode_error_on_direct_test_run.patch

messages: + msg118396
2010-10-11 21:50:50vstinnersetmessages: + msg118395
2010-10-09 08:59:06ocean-citysetfiles: - py3k_also_no_unicode_error_on_direct_test_run.patch
2010-10-09 08:58:46ocean-citysetmessages: + msg118256
2010-10-09 08:16:35vstinnersetmessages: + msg118253
2010-10-09 07:50:06ocean-citysetfiles: + py3k_also_no_unicode_error_on_direct_test_run.patch

messages: + msg118248
2010-09-10 11:10:43ocean-citysetfiles: + py3k_regrtest_newline_more.patch

messages: + msg116004
2010-09-10 11:08:22ocean-citysetfiles: + py3k_regrtest_newline.patch
nosy: + ocean-city
messages: + msg116003

2010-05-19 20:31:32vstinnerunlinkissue8589 dependencies
2010-05-07 00:59:18vstinnersetmessages: + msg105180
2010-05-05 21:31:09vstinnersetstatus: closed -> open
files: + regrtest_stdout_newline.patch
resolution: fixed -> (no value)
messages: + msg105087
2010-05-03 08:37:03vstinnersetstatus: open -> closed
resolution: fixed
messages: + msg104824
2010-05-02 17:25:47vstinnersetmessages: + msg104794
2010-05-02 11:08:23pitrousetstatus: pending -> open

messages: + msg104783
2010-05-02 09:39:26vstinnerlinkissue8589 dependencies
2010-05-02 09:38:16vstinnersetstatus: open -> pending

messages: + msg104773
2010-04-30 22:45:56vstinnersetfiles: - regrtest_traceback_stderr.patch
2010-04-30 22:45:49vstinnersetfiles: + regrtest_traceback_stderr-2.patch

messages: + msg104670
2010-04-26 12:49:22vstinnersetmessages: + msg104231
2010-04-26 12:47:23vstinnersetfiles: + regrtest_traceback_stderr.patch

messages: + msg104229
2010-04-26 11:30:37pitrousetnosy: + pitrou, flox
messages: + msg104223
2010-04-26 10:43:20vstinnersetcomponents: + Tests, Unicode
2010-04-26 10:43:12vstinnercreate