Add support for command invocation with a 'default verb'

colcon_core/command.py

@@ -117,7 +117,7 @@ def main(
     :param str verb_group_name: The extension point group name for verbs
     :param str environment_variable_group_name: The extension point group name
       for environment variables
-    :param VerbExtensionPoint default_verb: The verb to invoke if no explicit
+    :param Type default_verb: The verb class type to invoke if no explicit
       verb was provided on the command line
     :returns: The return code
     """
@@ -159,10 +159,11 @@ def _main(
     parser = create_parser(environment_variable_group_name)
 
     if default_verb is not None:
+        default_verb_instance = default_verb()
         parser.set_defaults(
-            verb_parser=parser, verb_extension=default_verb,
-            main=default_verb.main)
-        add_parser_arguments(parser, default_verb)
+            verb_parser=parser, verb_extension=default_verb_instance,
+            main=default_verb_instance.main)
+        add_parser_arguments(parser, default_verb_instance)
 
     verb_extensions = get_verb_extensions(group_name=verb_group_name)
 
@@ -189,7 +190,7 @@ def _main(
     colcon_logger.debug(f'Parsed command line arguments: {args}')
 
     # error: no verb provided
-    if args.verb_name is None and default_verb is None:
+    if not getattr(args, 'main', None):
         print(parser.format_usage())
         return 'Error: No verb provided'
 

test/test_command.py

@@ -97,27 +97,26 @@ def test_main_no_verbs_or_env():
 
 
 def test_main_default_verb():
-    default_verb = Extension2()
-    default_verb.main = Mock(wraps=default_verb.main)
     with ExtensionPointContext():
         with patch(
             'colcon_core.argument_parser.get_argument_parser_extensions',
             return_value={}
         ):
             with pytest.raises(SystemExit) as e:
-                main(argv=['--help'], default_verb=default_verb)
+                main(argv=['--help'], default_verb=Extension1)
             assert e.value.code == 0
 
             with pytest.raises(SystemExit) as e:
                 main(
                     argv=['--log-level', 'invalid'],
-                    default_verb=default_verb)
+                    default_verb=Extension1)
             assert e.value.code == 2
 
-            assert not main(
-                argv=['--log-base', '/dev/null'],
-                default_verb=default_verb)
-            default_verb.main.assert_called_once()
+            with patch.object(Extension1, 'main', return_value=0) as mock_main:
+                assert not main(
+                    argv=['--log-base', '/dev/null'],
+                    default_verb=Extension1)
+                mock_main.assert_called_once()
 
 
 def test_create_parser():