[Python-checkins] gh-103791: Make contextlib.suppress also act on exceptions within an ExceptionGroup (#103792)
ambv
webhook-mailer at python.org
Mon Apr 24 18:17:09 EDT 2023
https://github.com/python/cpython/commit/22bed58e531ce780d91f3364c5ace98fad28c2e8
commit: 22bed58e531ce780d91f3364c5ace98fad28c2e8
branch: main
author: Łukasz Langa <lukasz at langa.pl>
committer: ambv <lukasz at langa.pl>
date: 2023-04-24T22:17:02Z
summary:
gh-103791: Make contextlib.suppress also act on exceptions within an ExceptionGroup (#103792)
Co-authored-by: Irit Katriel <1055913+iritkatriel at users.noreply.github.com>
files:
A Lib/test/support/testcase.py
A Misc/NEWS.d/next/Library/2023-04-24-23-07-56.gh-issue-103791.bBPWdS.rst
M Doc/library/contextlib.rst
M Lib/contextlib.py
M Lib/test/test_contextlib.py
M Lib/test/test_except_star.py
diff --git a/Doc/library/contextlib.rst b/Doc/library/contextlib.rst
index 1b55868c3aa6..7cd081d1f54f 100644
--- a/Doc/library/contextlib.rst
+++ b/Doc/library/contextlib.rst
@@ -304,8 +304,15 @@ Functions and classes provided:
This context manager is :ref:`reentrant <reentrant-cms>`.
+ If the code within the :keyword:`!with` block raises an
+ :exc:`ExceptionGroup`, suppressed exceptions are removed from the
+ group. If any exceptions in the group are not suppressed, a group containing them is re-raised.
+
.. versionadded:: 3.4
+ .. versionchanged:: 3.12
+ ``suppress`` now supports suppressing exceptions raised as
+ part of an :exc:`ExceptionGroup`.
.. function:: redirect_stdout(new_target)
diff --git a/Lib/contextlib.py b/Lib/contextlib.py
index 30d9ac25b2bb..b5acbcb9e6d7 100644
--- a/Lib/contextlib.py
+++ b/Lib/contextlib.py
@@ -441,7 +441,16 @@ def __exit__(self, exctype, excinst, exctb):
# exactly reproduce the limitations of the CPython interpreter.
#
# See http://bugs.python.org/issue12029 for more details
- return exctype is not None and issubclass(exctype, self._exceptions)
+ if exctype is None:
+ return
+ if issubclass(exctype, self._exceptions):
+ return True
+ if issubclass(exctype, ExceptionGroup):
+ match, rest = excinst.split(self._exceptions)
+ if rest is None:
+ return True
+ raise rest
+ return False
class _BaseExitStack:
diff --git a/Lib/test/support/testcase.py b/Lib/test/support/testcase.py
new file mode 100644
index 000000000000..1e4363b15783
--- /dev/null
+++ b/Lib/test/support/testcase.py
@@ -0,0 +1,25 @@
+class ExceptionIsLikeMixin:
+ def assertExceptionIsLike(self, exc, template):
+ """
+ Passes when the provided `exc` matches the structure of `template`.
+ Individual exceptions don't have to be the same objects or even pass
+ an equality test: they only need to be the same type and contain equal
+ `exc_obj.args`.
+ """
+ if exc is None and template is None:
+ return
+
+ if template is None:
+ self.fail(f"unexpected exception: {exc}")
+
+ if exc is None:
+ self.fail(f"expected an exception like {template!r}, got None")
+
+ if not isinstance(exc, ExceptionGroup):
+ self.assertEqual(exc.__class__, template.__class__)
+ self.assertEqual(exc.args[0], template.args[0])
+ else:
+ self.assertEqual(exc.message, template.message)
+ self.assertEqual(len(exc.exceptions), len(template.exceptions))
+ for e, t in zip(exc.exceptions, template.exceptions):
+ self.assertExceptionIsLike(e, t)
diff --git a/Lib/test/test_contextlib.py b/Lib/test/test_contextlib.py
index ec06785b5667..0f8351ab8108 100644
--- a/Lib/test/test_contextlib.py
+++ b/Lib/test/test_contextlib.py
@@ -10,6 +10,7 @@
from contextlib import * # Tests __all__
from test import support
from test.support import os_helper
+from test.support.testcase import ExceptionIsLikeMixin
import weakref
@@ -1148,7 +1149,7 @@ class TestRedirectStderr(TestRedirectStream, unittest.TestCase):
orig_stream = "stderr"
-class TestSuppress(unittest.TestCase):
+class TestSuppress(ExceptionIsLikeMixin, unittest.TestCase):
@support.requires_docstrings
def test_instance_docs(self):
@@ -1202,6 +1203,30 @@ def test_cm_is_reentrant(self):
1/0
self.assertTrue(outer_continued)
+ def test_exception_groups(self):
+ eg_ve = lambda: ExceptionGroup(
+ "EG with ValueErrors only",
+ [ValueError("ve1"), ValueError("ve2"), ValueError("ve3")],
+ )
+ eg_all = lambda: ExceptionGroup(
+ "EG with many types of exceptions",
+ [ValueError("ve1"), KeyError("ke1"), ValueError("ve2"), KeyError("ke2")],
+ )
+ with suppress(ValueError):
+ raise eg_ve()
+ with suppress(ValueError, KeyError):
+ raise eg_all()
+ with self.assertRaises(ExceptionGroup) as eg1:
+ with suppress(ValueError):
+ raise eg_all()
+ self.assertExceptionIsLike(
+ eg1.exception,
+ ExceptionGroup(
+ "EG with many types of exceptions",
+ [KeyError("ke1"), KeyError("ke2")],
+ ),
+ )
+
class TestChdir(unittest.TestCase):
def make_relative_path(self, *parts):
diff --git a/Lib/test/test_except_star.py b/Lib/test/test_except_star.py
index c5167c5bba38..bc66f90b9cad 100644
--- a/Lib/test/test_except_star.py
+++ b/Lib/test/test_except_star.py
@@ -1,6 +1,7 @@
import sys
import unittest
import textwrap
+from test.support.testcase import ExceptionIsLikeMixin
class TestInvalidExceptStar(unittest.TestCase):
def test_mixed_except_and_except_star_is_syntax_error(self):
@@ -169,26 +170,7 @@ def f(x):
self.assertIsInstance(exc, ExceptionGroup)
-class ExceptStarTest(unittest.TestCase):
- def assertExceptionIsLike(self, exc, template):
- if exc is None and template is None:
- return
-
- if template is None:
- self.fail(f"unexpected exception: {exc}")
-
- if exc is None:
- self.fail(f"expected an exception like {template!r}, got None")
-
- if not isinstance(exc, ExceptionGroup):
- self.assertEqual(exc.__class__, template.__class__)
- self.assertEqual(exc.args[0], template.args[0])
- else:
- self.assertEqual(exc.message, template.message)
- self.assertEqual(len(exc.exceptions), len(template.exceptions))
- for e, t in zip(exc.exceptions, template.exceptions):
- self.assertExceptionIsLike(e, t)
-
+class ExceptStarTest(ExceptionIsLikeMixin, unittest.TestCase):
def assertMetadataEqual(self, e1, e2):
if e1 is None or e2 is None:
self.assertTrue(e1 is None and e2 is None)
diff --git a/Misc/NEWS.d/next/Library/2023-04-24-23-07-56.gh-issue-103791.bBPWdS.rst b/Misc/NEWS.d/next/Library/2023-04-24-23-07-56.gh-issue-103791.bBPWdS.rst
new file mode 100644
index 000000000000..f00384cde970
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2023-04-24-23-07-56.gh-issue-103791.bBPWdS.rst
@@ -0,0 +1,3 @@
+:class:`contextlib.suppress` now supports suppressing exceptions raised as
+part of an :exc:`ExceptionGroup`. If other exceptions exist on the group, they
+are re-raised in a group that does not contain the suppressed exceptions.
More information about the Python-checkins
mailing list