diff -r 917295aaad76 Lib/test/test_cmd.py
--- a/Lib/test/test_cmd.py	Mon Jul 30 00:01:44 2012 +0200
+++ b/Lib/test/test_cmd.py	Sun Jul 29 23:15:12 2012 -0400
@@ -221,10 +221,76 @@
              "(Cmd) *** Unknown syntax: EOF\n"))
 
 
+class TestNestedCLI(unittest.TestCase):
+
+    class InnerCLI(cmd.Cmd):
+        
+        def do_bar(self, s):
+            self.stdout.write('baz\n')
+    
+        def do_quit(self, s):
+            return True
+        
+        def do_EOF(self, args):
+            return True
+                
+    
+    class OuterCLI(cmd.Cmd):
+
+        def __init__(self, *arg, **kwargs):
+            cmd.Cmd.__init__(self, *arg, **kwargs)
+            self.register_subCLI('inner', TestNestedCLI.InnerCLI)
+            
+        def do_foo(self, s):
+            self.stdout.write('bar\n')
+            
+        def do_quit(self, s):
+            return True
+
+        def do_EOF(self, args):
+            return True
+
+        def register_subCLI(self, command_name, subcli_class):
+            '''Allows an inner Cmd instance (``subcli_class``)
+               to be invoked from an outer Cmd instance
+               via the ``command_name`` command.'''
+            _parent = self
+            def call_subcli(self):
+                subcli = subcli_class(stdin=_parent.stdin,
+                                      stdout=_parent.stdout)
+                subcli.use_rawinput = _parent.use_rawinput
+                subcli.cmdloop()
+            setattr(self, 'do_%s' % (command_name, ), call_subcli)        
+
+    def test_nested_subcli_works(self):
+        input = io.StringIO("foo \n inner \n bar \n quit \n")
+        output = io.StringIO()
+        cmd = self.OuterCLI(stdin=input, stdout=output)
+        cmd.use_rawinput = False
+        cmd.cmdloop()
+        self.assertMultiLineEqual(output.getvalue(),
+            ("(Cmd) bar\n"
+             "(Cmd) "
+             "(Cmd) baz\n"
+             "(Cmd) "
+             "(Cmd) "             
+             ))
+
+    def test_nested_subcli_appears_in_help(self):
+        input = io.StringIO("help \n")
+        output = io.StringIO()
+        cmd = self.OuterCLI(stdin=input, stdout=output)
+        cmd.use_rawinput = False
+        cmd.cmdloop()
+        self.assertIn("foo", output.getvalue())
+        self.assertIn("inner", output.getvalue())
+
+
 def test_main(verbose=None):
     from test import test_cmd
     support.run_doctest(test_cmd, verbose)
     support.run_unittest(TestAlternateInput)
+    support.run_unittest(TestNestedCLI)
 
 def test_coverage(coverdir):
     trace = support.import_module('trace')