Fix bug with mutually exclusive groups in parent= parsers.

2 files changed, 40 insertions, 0 deletions

diff --git a/argparse.py b/argparse.py
index 8950cc7..cb77a4a 100644
--- a/argparse.py
+++ b/argparse.py
@@ -1281,6 +1281,17 @@ class _ActionsContainer(object):
             for action in group._group_actions:
                 group_map[action] = title_group_map[group.title]
 
+        # add container's mutually exclusive groups
+        # NOTE: if add_mutually_exclusive_group ever gains title= and
+        # description= then this code will need to be expanded as above
+        for group in container._mutually_exclusive_groups:
+            mutex_group = self.add_mutually_exclusive_group(
+                required=group.required)
+
+            # map the actions to their new mutex group
+            for action in group._group_actions:
+                group_map[action] = mutex_group
+
         # add all actions to this container or their group
         for action in container._actions:
             group_map.get(action, self)._add_action(action)
diff --git a/test/test_argparse.py b/test/test_argparse.py
index 34a9c3f..6c8ee06 100644
--- a/test/test_argparse.py
+++ b/test/test_argparse.py
@@ -1848,6 +1848,35 @@ class TestParentParsers(TestCase):
               -y Y
         '''))
 
+    def test_groups_parents(self):
+        parent = ErrorRaisingArgumentParser(add_help=False)
+        g = parent.add_argument_group(title='g', description='gd')
+        g.add_argument('-w')
+        g.add_argument('-x')
+        m = parent.add_mutually_exclusive_group()
+        m.add_argument('-y')
+        m.add_argument('-z')
+        parser = ErrorRaisingArgumentParser(parents=[parent])
+
+        self.assertRaises(ArgumentParserError, parser.parse_args,
+            ['-y', 'Y', '-z', 'Z'])
+
+        parser_help = parser.format_help()
+        self.assertEqual(parser_help, textwrap.dedent('''\
+            usage: test_argparse.py [-h] [-w W] [-x X] [-y Y | -z Z]
+
+            optional arguments:
+              -h, --help  show this help message and exit
+              -y Y
+              -z Z
+
+            g:
+              gd
+
+              -w W
+              -x X
+        '''))
+
 # ==============================
 # Mutually exclusive group tests
 # ==============================