Index: Lib/test/test_argparse.py
===================================================================
--- Lib/test/test_argparse.py	(revision 83666)
+++ Lib/test/test_argparse.py	(working copy)
@@ -1713,6 +1713,20 @@
             NS(foo=True, bar=0.125, w=None, x='c'),
         )
 
+    def test_parse_known_args(self):
+        self.assertEqual(
+            self.parser.parse_known_args('0.5 1 b -w 7'.split()),
+            (NS(foo=False, bar=0.5, w=7, x='b'), []),
+        )
+        self.assertEqual(
+            self.parser.parse_known_args('0.5 1 b -w 7 -p'.split()),
+            (NS(foo=False, bar=0.5, w=7, x='b'), ['-p']),
+        )
+        self.assertEqual(
+            self.parser.parse_known_args('0.5 1 b -q -rs -w 7'.split()),
+            (NS(foo=False, bar=0.5, w=7, x='b'), ['-q', '-rs']),
+        )        
+
     def test_dest(self):
         parser = ErrorRaisingArgumentParser()
         parser.add_argument('--foo', action='store_true')