Allow to call initialize_app when running --help

Currently initialize_app is not called when running --help. Some
applications (like openstackclient) define its sub-commands in
initialize_app. So sub-commands are hidden when running '--help' except
if applications hack cliff to defer help print (openstackclient case).

This change defines a new option to allow deferring help print after
initialize_app. Openstackclient will be updated in a follow-up change
in order to remove previous hack.

Change-Id: I0c6fb93d5713654b180b4488e85118c1818fdfb0
Closes-Bug: #1316622

2 files changed, 49 insertions, 9 deletions

diff --git a/cliff/app.py b/cliff/app.py
index c2c8f50..6fd9a25 100644
--- a/cliff/app.py
+++ b/cliff/app.py
@@ -64,7 +64,8 @@ class App(object):
 
     def __init__(self, description, version, command_manager,
                  stdin=None, stdout=None, stderr=None,
-                 interactive_app_factory=InteractiveApp):
+                 interactive_app_factory=InteractiveApp,
+                 deferred_help=False):
         """Initialize the application.
         """
         self.command_manager = command_manager
@@ -72,6 +73,7 @@ class App(object):
         self.command_manager.add_command('complete', CompleteCommand)
         self._set_streams(stdin, stdout, stderr)
         self.interactive_app_factory = interactive_app_factory
+        self.deferred_help = deferred_help
         self.parser = self.build_option_parser(description, version)
         self.interactive_mode = False
         self.interpreter = None
@@ -144,13 +146,21 @@ class App(object):
             const=0,
             help='suppress output except warnings and errors',
         )
-        parser.add_argument(
-            '-h', '--help',
-            action=HelpAction,
-            nargs=0,
-            default=self,  # tricky
-            help="show this help message and exit",
-        )
+        if self.deferred_help:
+            parser.add_argument(
+                '-h', '--help',
+                dest='deferred_help',
+                action='store_true',
+                help="show this help message and exit",
+            )
+        else:
+            parser.add_argument(
+                '-h', '--help',
+                action=HelpAction,
+                nargs=0,
+                default=self,  # tricky
+                help="show this help message and exit",
+            )
         parser.add_argument(
             '--debug',
             default=False,
@@ -186,6 +196,11 @@ class App(object):
         root_logger.addHandler(console)
         return
 
+    def print_help_if_requested(self):
+        if self.deferred_help and self.options.deferred_help:
+            action = HelpAction(None, None, default=self)
+            action(self.parser, self.parser, None, None)
+
     def run(self, argv):
         """Equivalent to the main program for the application.
 
@@ -197,6 +212,7 @@ class App(object):
             self.configure_logging()
             self.interactive_mode = not remainder
             self.initialize_app(remainder)
+            self.print_help_if_requested()
         except Exception as err:
             if hasattr(self, 'options'):
                 debug = self.options.debug
diff --git a/cliff/tests/test_app.py b/cliff/tests/test_app.py
index efff788..b15ef40 100644
--- a/cliff/tests/test_app.py
+++ b/cliff/tests/test_app.py
@@ -15,7 +15,7 @@ from cliff.command import Command
 from cliff.commandmanager import CommandManager
 
 
-def make_app():
+def make_app(**kwargs):
     cmd_mgr = CommandManager('cliff.tests')
 
     # Register a command that succeeds
@@ -38,6 +38,7 @@ def make_app():
               '1',
               cmd_mgr,
               stderr=mock.Mock(),  # suppress warning messages
+              **kwargs
               )
     return app, command
 
@@ -376,6 +377,29 @@ def test_error_encoding_sys():
                 assert data == actual
 
 
+def _test_help(deferred_help):
+    app, _ = make_app(deferred_help=deferred_help)
+    with mock.patch.object(app, 'initialize_app') as init:
+        with mock.patch('cliff.help.HelpAction.__call__',
+                        side_effect=SystemExit(0)) as helper:
+            try:
+                app.run(['--help'])
+            except SystemExit:
+                pass
+            else:
+                raise Exception('Exception was not thrown')
+            assert helper.called
+        assert init.called == deferred_help
+
+
+def test_help():
+    _test_help(False)
+
+
+def test_deferred_help():
+    _test_help(True)
+
+
 def test_unknown_cmd():
     app, command = make_app()
     assert app.run(['hell']) == 2