Use safe_str() to format warning message about unicode in Python 2

Fix #3691
This commit is contained in:
Bruno Oliveira 2018-10-18 19:42:25 -03:00
parent e4871f7722
commit 18035211f5
3 changed files with 32 additions and 1 deletions

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@ -0,0 +1,2 @@
Python 2: safely format warning message about passing unicode strings to ``warnings.warn``, which may cause
surprising ``MemoryError`` exception when monkey patching ``warnings.warn`` itself.

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@ -123,7 +123,7 @@ def warning_record_to_str(warning_message):
if unicode_warning: if unicode_warning:
warnings.warn( warnings.warn(
"Warning is using unicode non convertible to ascii, " "Warning is using unicode non convertible to ascii, "
"converting to a safe representation:\n %s" % msg, "converting to a safe representation:\n {!r}".format(compat.safe_str(msg)),
UnicodeWarning, UnicodeWarning,
) )
return msg return msg

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@ -3,6 +3,8 @@ from __future__ import unicode_literals
import sys import sys
import six
import pytest import pytest
@ -562,3 +564,30 @@ class TestDeprecationWarningsByDefault:
monkeypatch.setenv(str("PYTHONWARNINGS"), str("once::UserWarning")) monkeypatch.setenv(str("PYTHONWARNINGS"), str("once::UserWarning"))
result = testdir.runpytest_subprocess() result = testdir.runpytest_subprocess()
assert WARNINGS_SUMMARY_HEADER not in result.stdout.str() assert WARNINGS_SUMMARY_HEADER not in result.stdout.str()
@pytest.mark.skipif(six.PY3, reason="Python 2 only issue")
def test_infinite_loop_warning_against_unicode_usage_py2(testdir):
"""
We need to be careful when raising the warning about unicode usage with "warnings.warn"
because it might be overwritten by users and this itself causes another warning (#3691).
"""
testdir.makepyfile(
"""
# -*- coding: utf8 -*-
from __future__ import unicode_literals
import warnings
import pytest
def _custom_showwarning(message, *a, **b):
return "WARNING: {}".format(message)
warnings.formatwarning = _custom_showwarning
@pytest.mark.filterwarnings("default")
def test_custom_warning_formatter():
warnings.warn("¥")
"""
)
result = testdir.runpytest_subprocess()
result.stdout.fnmatch_lines(["*1 passed, * warnings in*"])