test_pyrepl.test_no_newline() failure on main

[smontanaro]

Bug report

Bug description:

test_pyrepl started failing for me a day or two ago. According to git bisect, this is the problematic commit:

8a2deea1fc725f8147254f87c6042fcf75a1d03b is the first bad commit
commit 8a2deea1fc725f8147254f87c6042fcf75a1d03b
Author: Jan-Eric Nitschke <47750513+JanEricNitschke@users.noreply.github.com>
Date:   Fri Jan 2 14:04:37 2026 +0100

    gh-128067: Fix pyrepl overriding printed output without newlines (#138732)
    
    Co-authored-by: Łukasz Langa <lukasz@langa.pl>

 Lib/_pyrepl/unix_console.py                                        |  7 +++---
 Lib/_pyrepl/windows_console.py                                     |  7 +++---
 Lib/test/test_pyrepl/test_pyrepl.py                                | 38 +++++++++++++++++++++++++++++++
 Lib/test/test_pyrepl/test_unix_console.py                          | 14 ++++++++++++
 Lib/test/test_pyrepl/test_windows_console.py                       | 14 ++++++++++++
 Misc/ACKS                                                          |  1 +
 .../next/Windows/2025-09-14-13-35-44.gh-issue-128067.BGdP_A.rst    |  1 +
 7 files changed, 76 insertions(+), 6 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Windows/2025-09-14-13-35-44.gh-issue-128067.BGdP_A.rst

CPython versions tested on:

CPython main branch

Operating systems tested on:

macOS

Linked PRs

• gh-143394: filter for turning off automatic margins in test_no_newline #143433
• [3.14] gh-143394: filter for turning off automatic margins in test_no_newline (GH-143433) #143459
• gh-143394: On macOS, run main PyREPL tests as "Apple Terminal" as well #143461
• [3.14] gh-143394: On macOS, run main PyREPL tests as "Apple Terminal" as well (GH-143461) #143466
• [3.13] gh-143394: On macOS, run main PyREPL tests as "Apple Terminal" as well (GH-143461) #143467
• [3.13] gh-143394: filter for turning off automatic margins in test_no_newline (GH-143433) #143478
• gh-143394: Skip pyrepl test_no_newline() basic REPL if readline is missing #147973
• [3.14] gh-143394: Skip pyrepl test_no_newline() basic REPL if readline is missing (GH-147973) #148005
• [3.13] gh-143394: Skip pyrepl test_no_newline() basic REPL if readline is missing (GH-147973) #148006

[johnslavik]

What are the failures you're seeing exactly? Which tests are failing exactly? @ZeroIntensity topic-repl pending (I'd skip any other labels because we don't have enough information)

[smontanaro]

Sorry, forgot the key bit.

======================================================================
FAIL: test_no_newline (test.test_pyrepl.test_pyrepl.TestMain.test_no_newline)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/skip/src/python/cpython/Lib/test/support/__init__.py", line 3022, in wrapper
    return func(*args, **kwargs)
  File "/Users/skip/src/python/cpython/Lib/test/test_pyrepl/test_pyrepl.py", line 1909, in test_no_newline
    self.assertIn(expected_output_sequence, cleaned_output)
    ~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: 'Something pretty long>>> exit()' not found in 'print(\'Something pretty long\', end=\'\')\r\nexit()\r\nPython 3.15.0a3+ free-threading build (bisect/good-18f3c59e57e5d30218210136060310310b10ff72-2-g09ce5924996:09ce5924996,) [Clang 21.1.8 ] on darwin\r\nType "help", "copyright", "credits" or "license" for more information.\r\n\x1b[?7l>>> print(\'Something pretty long\', end=\'\')\x1b[42D\n\r\x1b[?7hSomething pretty long\x1b[?7l>>> exit()\x1b[10D\n\r\x1b[?7h'

[johnslavik]

Notes: cleaned_output contained unexpected ANSI sequences, free-threaded build (unlikely to be related).

[smontanaro]

Failing on 3.14 branch as well.

======================================================================
FAIL: test_no_newline (test.test_pyrepl.test_pyrepl.TestMain.test_no_newline)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/skip/src/python/py3.14/Lib/test/support/__init__.py", line 2935, in wrapper
    return func(*args, **kwargs)
  File "/Users/skip/src/python/py3.14/Lib/test/test_pyrepl/test_pyrepl.py", line 1899, in test_no_newline
    self.assertIn(expected_output_sequence, cleaned_output)
    ~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: 'Something pretty long>>> exit()' not found in 'print(\'Something pretty long\', end=\'\')\r\nexit()\r\nPython 3.14.2+ free-threading build (heads/3.14:6583951e7de, Dec 29 2025, 09:10:49) [Clang 21.1.8 ] on darwin\r\nType "help", "copyright", "credits" or "license" for more information.\r\n\x1b[?7l>>> print(\'Something pretty long\', end=\'\')\x1b[42D\n\r\x1b[?7hSomething pretty long\x1b[?7l>>> exit()\x1b[10D\n\r\x1b[?7h'

[johnslavik]

For the passing case, cleaned_output ends with

Something pretty long>>> exit()\x1b[10D\n\r

For the OP's case, cleaned_output ends with

Something pretty long\x1b[?7l>>> exit()\x1b[10D\n\r\x1b[?7h

The presence of \x1b[?7l prevented the test from passing.

[johnslavik]

As noted, this is related to GH-138732. CC @JanEricNitschke @chris-eibl

@ambv, this looks similar to the builbot failure from GH-138732 where \x1b[34h popped up. However, this issue appeared on MacOS and the sequence was \x1b[?7l.

Not sure whether this is tests or stdlib -- auto-wrap mode from ?7h and ?7l may technically change the visual output and cursor position. Please confirm me on that though.

@ZeroIntensity 3.13 3.14 3.15 (and topic-repl of course)

[chris-eibl]

test_no_newline needs a lot of filtering, and that's why I suggested two easier tests additionally. Łukasz already hardened test_no_newline in #143356.

We can try to filter for \x1b[?7l as well, but if test_no_newline gets a maintenance burden, IMHO we can just remove it, too?

[chris-eibl]

@smontanaro does adding

safe_patterns.append(r'\x1b[?7l')  # auto wrap

fix the issue for you?

[johnslavik]

If that's the case, let's relabel this as tests @picnixz (not stdlib)