diff --git a/Lib/argparse.py b/Lib/argparse.py index ce4635adcbf..f1f6f3227bd 100644 --- a/Lib/argparse.py +++ b/Lib/argparse.py @@ -526,12 +526,13 @@ class HelpFormatter(object): parts = [action_header] # if there was help for the action, add lines of help text - if action.help: + if action.help and action.help.strip(): help_text = self._expand_help(action) - help_lines = self._split_lines(help_text, help_width) - parts.append('%*s%s\n' % (indent_first, '', help_lines[0])) - for line in help_lines[1:]: - parts.append('%*s%s\n' % (help_position, '', line)) + if help_text: + help_lines = self._split_lines(help_text, help_width) + parts.append('%*s%s\n' % (indent_first, '', help_lines[0])) + for line in help_lines[1:]: + parts.append('%*s%s\n' % (help_position, '', line)) # or add a newline if the description doesn't end with one elif not action_header.endswith('\n'): diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py index 0927281f69c..6680feb016a 100644 --- a/Lib/test/test_argparse.py +++ b/Lib/test/test_argparse.py @@ -2145,6 +2145,42 @@ class TestAddSubparsers(TestCase): wrap\N{NO-BREAK SPACE}at non-breaking spaces ''')) + def test_help_blank(self): + # Issue 24444 + parser = ErrorRaisingArgumentParser( + prog='PROG', description='main description') + parser.add_argument( + 'foo', + help=' ') + self.assertEqual(parser.format_help(), textwrap.dedent('''\ + usage: PROG [-h] foo + + main description + + positional arguments: + foo + + options: + -h, --help show this help message and exit + ''')) + + parser = ErrorRaisingArgumentParser( + prog='PROG', description='main description') + parser.add_argument( + 'foo', choices=[], + help='%(choices)s') + self.assertEqual(parser.format_help(), textwrap.dedent('''\ + usage: PROG [-h] {} + + main description + + positional arguments: + {} + + options: + -h, --help show this help message and exit + ''')) + def test_help_alternate_prefix_chars(self): parser = self._get_parser(prefix_chars='+:/') self.assertEqual(parser.format_usage(), diff --git a/Misc/NEWS.d/next/Library/2021-08-30-00-19-23.bpo-24444.Ki4bgz.rst b/Misc/NEWS.d/next/Library/2021-08-30-00-19-23.bpo-24444.Ki4bgz.rst new file mode 100644 index 00000000000..efcacb8f0eb --- /dev/null +++ b/Misc/NEWS.d/next/Library/2021-08-30-00-19-23.bpo-24444.Ki4bgz.rst @@ -0,0 +1,2 @@ +Fixed an error raised in :mod:`argparse` help display when help for an +option is set to 1+ blank spaces or when *choices* arg is an empty container.