Fixing read before prompt bug

Due to Python buffering sys.stdin and sys.stdout, the read can be shown
before text prompt.

Change-Id: I86d9ec62f7791da276585ce74a48162315effa7b
Signed-off-by: Joe Borg <joe@josephb.org>

heatclient/osc/v1/stack.py

@@ -684,9 +684,9 @@ class DeleteStack(command.Command):
 
         try:
             if not parsed_args.yes and sys.stdin.isatty():
-                sys.stdout.write(
-                    _("Are you sure you want to delete this stack(s) [y/N]? "))
-                prompt_response = sys.stdin.readline().lower()
+                prompt_response = six.moves.input(
+                    _("Are you sure you want to delete this stack(s) [y/N]? ")
+                ).lower()
                 if not prompt_response.startswith('y'):
                     self.log.info('User did not confirm stack delete so '
                                   'taking no action.')

heatclient/tests/unit/test_shell.py

@@ -2067,6 +2067,7 @@ class ShellTestUserPass(ShellBase):
         mock_stdin.isatty.return_value = True
         mock_stdin.readline = mock.Mock()
         mock_stdin.readline.return_value = 'n'
+        mock_stdin.fileno.return_value = 0
         sys.stdin = mock_stdin
 
         self.mock_request_delete('/stacks/teststack2/2', None)
@@ -2078,7 +2079,7 @@ class ShellTestUserPass(ShellBase):
         self.assertEqual(resp_text, resp)
         self.m.ReplayAll()
 
-        mock_stdin.readline.return_value = 'Y'
+        mock_stdin.readline.return_value = 'y'
         resp = self.shell('stack-delete teststack2/2')
         msg = 'Request to delete stack teststack2/2 has been accepted.'
         self.assertRegex(resp, msg)
@@ -2093,6 +2094,7 @@ class ShellTestUserPass(ShellBase):
         mock_stdin.isatty.return_value = True
         mock_stdin.readline = mock.Mock()
         mock_stdin.readline.return_value = ''
+        mock_stdin.fileno.return_value = 0
         sys.stdin = mock_stdin
 
         self.mock_request_delete('/stacks/teststack2/2')

heatclient/v1/shell.py

@@ -302,9 +302,9 @@ def do_stack_delete(hc, args):
 
     try:
         if not args.yes and sys.stdin.isatty():
-            sys.stdout.write(
-                _("Are you sure you want to delete this stack(s) [y/N]? "))
-            prompt_response = sys.stdin.readline().lower()
+            prompt_response = six.moves.input(
+                _("Are you sure you want to delete this stack(s) [y/N]? ")
+            ).lower()
             if not prompt_response.startswith('y'):
                 logger.info(
                     'User did not confirm stack delete so taking no action.')