bpo-26967: fix flag grouping with allow_abbrev=False (GH-14316) (GH-14759)
The `allow_abbrev` option for ArgumentParser is documented and intended to disable support for unique prefixes of --options, which may sometimes be ambiguous due to deferred parsing.
However, the initial implementation also broke parsing of grouped short flags, such as `-ab` meaning `-a -b` (or `-a=b`). Checking the argument for a leading `--` before rejecting it fixes this.
This was prompted by pytest-dev/pytestGH-5469, so a backport to at least 3.8 would be great :smile:
And this is my first PR to CPython, so please let me know if I've missed anything!
https://bugs.python.org/issue26967
(cherry picked from commit dffca9e925ee5c3072663cbe8d4d4768406d5307)
Co-authored-by: Zac Hatfield-Dodds <Zac-HD@users.noreply.github.com>
diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py
index 9079d4b..5128dc5 100644
--- a/Lib/test/test_argparse.py
+++ b/Lib/test/test_argparse.py
@@ -785,6 +785,25 @@
('--foonly 7 --foodle --foo 2', NS(foo='2', foodle=True, foonly='7')),
]
+
+class TestDisallowLongAbbreviationAllowsShortGrouping(ParserTestCase):
+ """Do not allow abbreviations of long options at all"""
+
+ parser_signature = Sig(allow_abbrev=False)
+ argument_signatures = [
+ Sig('-r'),
+ Sig('-c', action='count'),
+ ]
+ failures = ['-r', '-c -r']
+ successes = [
+ ('', NS(r=None, c=None)),
+ ('-ra', NS(r='a', c=None)),
+ ('-rcc', NS(r='cc', c=None)),
+ ('-cc', NS(r=None, c=2)),
+ ('-cc -ra', NS(r='a', c=2)),
+ ('-ccrcc', NS(r='cc', c=2)),
+ ]
+
# ================
# Positional tests
# ================