FIX: -A and --args should behave the same. (#6223)

* FIX: -A and --args should behave the same.

Closes #4558

The added test should fail like this, without this patch:

AssertionError: assert 't.unit.bin.test_celery.APP' == 'worker'

* Remove dead code.

* Feel that this should be kept untouched.

celery/bin/base.py

@@ -474,7 +474,7 @@ def prepare_parser(self, parser):
         return parser
 
     def setup_app_from_commandline(self, argv):
-        preload_options = self.parse_preload_options(argv)
+        preload_options, remaining_options = self.parse_preload_options(argv)
         quiet = preload_options.get('quiet')
         if quiet is not None:
             self.quiet = quiet
@@ -510,18 +510,18 @@ def setup_app_from_commandline(self, argv):
             elif self.app is None:
                 self.app = self.get_app(loader=loader)
             if self.enable_config_from_cmdline:
-                argv = self.process_cmdline_config(argv)
+                remaining_options = self.process_cmdline_config(remaining_options)
         else:
             self.app = Celery(fixups=[])
 
         self._handle_user_preload_options(argv)
 
-        return argv
+        return remaining_options
 
     def _handle_user_preload_options(self, argv):
         user_preload = tuple(self.app.user_options['preload'] or ())
         if user_preload:
-            user_options = self._parse_preload_options(argv, user_preload)
+            user_options, _ = self._parse_preload_options(argv, user_preload)
             signals.user_preload_options.send(
                 sender=self, app=self.app, options=user_options,
             )
@@ -550,8 +550,8 @@ def _parse_preload_options(self, args, options):
         args = [arg for arg in args if arg not in ('-h', '--help')]
         parser = self.Parser()
         self.add_compat_options(parser, options)
-        namespace, _ = parser.parse_known_args(args)
-        return vars(namespace)
+        namespace, unknown_args = parser.parse_known_args(args)
+        return vars(namespace), unknown_args
 
     def add_append_opt(self, acc, opt, value):
         default = opt.default or []

celery/bin/celery.py

@@ -435,6 +435,13 @@ def on_usage_error(self, exc, command=None):
         )))
 
     def _relocate_args_from_start(self, argv, index=0):
+        """Move options to the end of args.
+
+        This rewrites:
+            -l debug worker -c 3
+        to:
+            worker -c 3 -l debug
+        """
         if argv:
             rest = []
             while index < len(argv):
@@ -466,9 +473,6 @@ def _relocate_args_from_start(self, argv, index=0):
                 # we assume the first argument in argv[i:] is the command
                 # name.
                 return argv[index:] + rest
-            # if there are no more arguments then the last arg in rest'
-            # must be the command.
-            [rest.pop()] + rest
         return []
 
     def prepare_prog_name(self, name):

t/unit/bin/test_base.py

@@ -353,7 +353,7 @@ class TestCommand(Command):
             def add_preload_arguments(self, parser):
                 parser.add_argument('-s', action='store', dest='silent')
         cmd = TestCommand()
-        acc = cmd.parse_preload_options(['-s', 'yes'])
+        acc, _ = cmd.parse_preload_options(['-s', 'yes'])
         assert acc.get('silent') == 'yes'
 
     def test_parse_preload_options_with_equals_and_append(self):
@@ -363,14 +363,14 @@ class TestCommand(Command):
             def add_preload_arguments(self, parser):
                 parser.add_argument('--zoom', action='append', default=[])
         cmd = Command()
-        acc = cmd.parse_preload_options(['--zoom=1', '--zoom=2'])
+        acc, _ = cmd.parse_preload_options(['--zoom=1', '--zoom=2'])
 
         assert acc, {'zoom': ['1' == '2']}
 
     def test_parse_preload_options_without_equals_and_append(self):
         cmd = Command()
         opt = Option('--zoom', action='append', default=[])
         cmd.preload_options = (opt,)
-        acc = cmd.parse_preload_options(['--zoom', '1', '--zoom', '2'])
+        acc, _ = cmd.parse_preload_options(['--zoom', '1', '--zoom', '2'])
 
         assert acc, {'zoom': ['1' == '2']}

t/unit/bin/test_celery.py

@@ -16,6 +16,13 @@
 from celery.platforms import EX_FAILURE, EX_OK, EX_USAGE
 
 
+class MyApp(object):
+    user_options = {'preload': None}
+
+
+APP = MyApp()  # <-- Used by test_short_and_long_arguments_be_the_same
+
+
 class test__main__:
 
     def test_main(self):
@@ -204,6 +211,17 @@ def test_handle_argv(self):
         x.handle_argv('celery', ['start', 'foo'])
         x.execute.assert_called_with('start', ['start', 'foo'])
 
+    def test_short_and_long_arguments_be_the_same(self):
+        for arg in "--app", "-A":
+            appstr = '.'.join([__name__, 'APP'])
+            x = CeleryCommand(app=self.app)
+            x.execute = Mock()
+            with pytest.raises(SystemExit):
+                x.execute_from_commandline(['celery', arg, appstr, 'worker'])
+            assert x.execute.called
+            assert x.execute.call_args[0]
+            assert x.execute.call_args[0][0] == "worker"
+
     def test_execute(self):
         x = CeleryCommand(app=self.app)
         Help = x.commands['help'] = Mock()