3.11.5 test_httpservers fails on unhandled DeprecationWarning ("invalid escape sequence '\\?'")

[dvzrv]

Bug report

Checklist

• I am confident this is a bug in CPython, not a bug in a third-party project
• I have searched the CPython issue tracker,
  and am confident this bug has not been reported before

CPython versions tested on:

3.11

Operating systems tested on:

Linux

Output from running 'python -VV' on the command line:

Python 3.11.3 (main, Jun 5 2023, 09:32:32) [GCC 13.1.1 20230429]

A clear and concise description of the bug:

Hi! When attempting to upgrade the python package for Arch Linux to 3.11.5 I ran into the following test issue:

[..]
test.test_httpservers
FAIL

======================================================================
FAIL: test_all (test.test___all__.AllTest.test_all)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/build/python/src/Python-3.11.5/Lib/test/test___all__.py", line 129, in test_all
    self.check_all(modname)
  File "/build/python/src/Python-3.11.5/Lib/test/test___all__.py", line 43, in check_all
    with warnings_helper.check_warnings(
  File "/build/python/src/Python-3.11.5/Lib/contextlib.py", line 144, in __exit__
    next(self.gen)
  File "/build/python/src/Python-3.11.5/Lib/test/support/warnings_helper.py", line 185, in _filterwarnings
    raise AssertionError("unhandled warning %s" % reraise[0])
AssertionError: unhandled warning {message : DeprecationWarning("invalid escape sequence '\\?'"), category : 'DeprecationWarning', filename : '/build/python/src/Python-3.11.5/Lib/test/test_httpservers.py', lineno : 445, line : None}

----------------------------------------------------------------------
Ran 1 test in 0.621s

FAILED (failures=1)
test test___all__ failed
0:00:05 load avg: 3.34 [ 12/432/1] test___future__ -- test___all__ failed (1 failure)
test_attributes (test.test___future__.FutureTest.test_attributes) ... ok
test_names (test.test___future__.FutureTest.test_names) ... ok

----------------------------------------------------------------------
Ran 2 tests in 0.000s
[..]

Full build and check logs:
python-3.11.5-1-x86_64-build.log
python-3.11.5-1-x86_64-check.log

Build script for the package: https://gitlab.archlinux.org/archlinux/packaging/packages/python/-/blob/main/PKGBUILD

cc @felixonmars

[hugovk]

The f-string was turned into a raw f-string for main and 3.12, but not 3.11:

• test___all__.AllTest.test_all is failing on every PR #105821
• gh-105821: Use a raw f-string in test_httpservers.py #105822
• [3.12] gh-105821: Use a raw f-string in test_httpservers.py (GH-105822) #105824

@pablogsal @AlexWaygood Shall we backport it to 3.11?

[AlexWaygood]

@pablogsal @AlexWaygood Shall we backport it to 3.11?

That makes sense to me; the change is very low-risk 👍

@dvzrv, are you running your tests with -W/-Werror? (I'm curious why we're not seeing the same test failures in CI over at CPython!)

[pablogsal]

Let's do the backport! 👍

Also let's investigate as well why we are didn't experience this in our own Ci. 🤔

[AlexWaygood]

I triggered the backport, and I've enabled automerge:

• [3.11] gh-105821: Use a raw f-string in test_httpservers.py (GH-105822) #108576

[dvzrv]

@dvzrv, are you running your tests with -W/-Werror? (I'm curious why we're not seeing the same test failures in CI over at CPython!)

Not that I am aware of (definitely not explicitly).

Rebuilding with the patch applied now to see where this leads and will report back. Thanks for the super quick responses here!

[dvzrv]

Building with #108576 applied on top of 3.11.5 fixes the issue for us. Thank you! :)

[hugovk]

Also let's investigate as well why we are didn't experience this in our own Ci. 🤔

Because we're no longer running Lib/test/test___all__.py on the CI.

Here's the last build before the backport (33eee43):

https://github.com/python/cpython/actions/runs/6000276301/job/16272033246

Checking out 33eee43 locally, building and running the test fails:

❯ ./python.exe ./Lib/test/test___all__.py
__hello__
__phello__
__phello__.ham
...
test.test_http_cookies
test.test_httplib
test.test_httpservers
F
======================================================================
FAIL: test_all (__main__.AllTest.test_all)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/hugo/github/cpython/./Lib/test/test___all__.py", line 129, in test_all
    self.check_all(modname)
  File "/Users/hugo/github/cpython/./Lib/test/test___all__.py", line 43, in check_all
    with warnings_helper.check_warnings(
  File "/Users/hugo/github/cpython/Lib/contextlib.py", line 144, in __exit__
    next(self.gen)
  File "/Users/hugo/github/cpython/Lib/test/support/warnings_helper.py", line 185, in _filterwarnings
    raise AssertionError("unhandled warning %s" % reraise[0])
AssertionError: unhandled warning {message : DeprecationWarning("invalid escape sequence '\\?'"), category : 'DeprecationWarning', filename : '/Users/hugo/github/cpython/Lib/test/test_httpservers.py', lineno : 445, line : None}

----------------------------------------------------------------------
Ran 1 test in 1.284s

FAILED (failures=1)

(Note: running it a second time passes, some intermediary files need to be deleted first.)

---

test___all___ was added to the CI in #26640 and skipped in #30897 (both by @pablogsal) and then skipped in a different way in #31632.