diff --git a/Doc/library/contextlib.rst b/Doc/library/contextlib.rst index 1b55868c3aa62f..7cd081d1f54f43 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 `. + 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 30d9ac25b2bbec..b5acbcb9e6d77c 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 00000000000000..1e4363b15783eb --- /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 ec06785b5667a6..0f8351ab8108a6 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 c5167c5bba38af..bc66f90b9cad45 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 00000000000000..f00384cde9706e --- /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.