8000 bpo-36829: Document test.support.catch_unraisable_exception() (GH-13554) · python/cpython@6dbbe74 · GitHub
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bpo-36829: Document test.support.catch_unraisable_exception() (GH-13554)
catch_unraisable_exception() now also removes its 'unraisable' attribute at the context manager exit.
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‎Doc/library/test.rst

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@@ -1081,6 +1081,26 @@ The :mod:`test.support` module defines the following functions:
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:exc:`PermissionError` is raised.
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.. function:: catch_unraisable_exception()
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Context manager catching unraisable exception using
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:func:`sys.unraisablehook`.
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Usage::
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with support.catch_unraisable_exception() as cm:
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# code creating an "unraisable exception"
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...
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# check the unraisable exception: use cm.unraisable
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...
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# cm.unraisable attribute no longer exists at this point
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# (to break a reference cycle)
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.. versionadded:: 3.8
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.. function:: find_unused_port(family=socket.AF_INET, socktype=socket.SOCK_STREAM)
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Returns an unused port that should be suitable for binding. This is

‎Lib/test/support/__init__.py

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@@ -3043,12 +3043,14 @@ class catch_unraisable_exception:
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Usage:
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with support.catch_unraisable_exception() as cm:
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# code creating an "unraisable exception"
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...
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# check the expected unraisable exception: use cm.unraisable
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# check the unraisable exception: use cm.unraisable
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...
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# cm.unraisable is None here (to break a reference cycle)
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# cm.unraisable attribute no longer exists at this point
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# (to break a reference cycle)
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"""
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def __init__(self):
@@ -3065,5 +3067,5 @@ def __enter__(self):
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def __exit__(self, *exc_info):
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# Clear the unraisable exception to explicitly break a reference cycle
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self.unraisable = None
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del self.unraisable
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sys.unraisablehook = self._old_hook

‎Lib/test/test_io.py

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Original file line numberDiff line numberDiff line change
@@ -1098,18 +1098,14 @@ def test_error_through_destructor(self):
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# Test that the exception state is not modified by a destructor,
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# even if close() fails.
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rawio = self.CloseFailureIO()
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try:
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with support.catch_unraisable_exception() as cm:
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with self.assertRaises(AttributeError):
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self.tp(rawio).xyzzy
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with support.catch_unraisable_exception() as cm:
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with self.assertRaises(AttributeError):
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self.tp(rawio).xyzzy
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if not IOBASE_EMITS_UNRAISABLE:
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self.assertIsNone(cm.unraisable)
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elif cm.unraisable is not None:
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self.assertEqual(cm.unraisable.exc_type, OSError)
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finally:
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# Explicitly break reference cycle
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cm = None
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def test_repr(self):
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raw = self.MockRawIO()
@@ -2854,18 +2850,14 @@ def test_error_through_destructor(self):
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# Test that the exception state is not modified by a destructor,
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# even if close() fails.
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rawio = self.CloseFailureIO()
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try:
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with support.catch_unraisable_exception() as cm:
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with self.assertRaises(AttributeError):
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self.TextIOWrapper(rawio).xyzzy
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with support.catch_unraisable_exception() as cm:
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with self.assertRaises(AttributeError):
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self.TextIOWrapper(rawio).xyzzy
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if not IOBASE_EMITS_UNRAISABLE:
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self.assertIsNone(cm.unraisable)
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elif cm.unraisable is not None:
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self.assertEqual(cm.unraisable.exc_type, OSError)
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finally:
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# Explicitly break reference cycle
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cm = None
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# Systematic tests of the text I/O API
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