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Code Issues Projects Releases Packages Wiki Activity Actions 11

bpo-26952: [argparse] clearer error when formatting an empty mutually… (GH-30099)

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Irit Katriel 2021-12-15 10:08:26 +00:00 • committed by GitHub
parent f54fee7f37
commit 86de99588d
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3
Lib/argparse.py
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@ -392,6 +392,9 @@ class HelpFormatter(object):
group_actions = set() group_actions = set()
inserts = {} inserts = {}
for group in groups: for group in groups:
if not group._group_actions:
raise ValueError(f'empty group {group}')
try: try:
start = actions.index(group._group_actions[0]) start = actions.index(group._group_actions[0])
except ValueError: except ValueError:

7
Lib/test/test_argparse.py
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@ -2601,6 +2601,13 @@ class TestMutuallyExclusiveGroupErrors(TestCase):
''' '''
self.assertEqual(parser.format_help(), textwrap.dedent(expected)) self.assertEqual(parser.format_help(), textwrap.dedent(expected))
def test_empty_group(self):
# See issue 26952
parser = argparse.ArgumentParser()
group = parser.add_mutually_exclusive_group()
with self.assertRaises(ValueError):
parser.parse_args(['-h'])
class MEMixin(object): class MEMixin(object):
def test_failures_when_not_required(self): def test_failures_when_not_required(self):

1
Misc/NEWS.d/next/Library/2021-12-14-13-18-45.bpo-26952.hjhISq.rst Normal file
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@ -0,0 +1 @@
:mod:`argparse` raises :exc:`ValueError` with clear message when trying to render usage for an empty mutually-exclusive group. Previously it raised a cryptic :exc:`IndexError`.