Allow passing in multiple tag names to the validation decorator.

We have problems when we try to wrap one decorator around another.
There are ways to do that with the
[decorator](https://pypi.python.org/pypi/decorator) module nicely,
however.. they are ugly.

Take a look at this:

https://github.com/micheles/decorator/blob/master/src/decorator.py#L217-L218

And this:

https://github.com/micheles/decorator/blob/master/src/decorator.py#L185-L188

The approach in this PR is.. simpler.

module_build_service/builder.py

@@ -691,8 +691,7 @@ chmod 644 %buildroot/%_rpmconfigdir/macros.d/macros.modules
                 raise SystemError("Unknown tag: %s" % tag)
         return taginfo
 
-    @module_build_service.utils.validate_koji_tag('tag_name')
-    @module_build_service.utils.validate_koji_tag('parent_tags')
+    @module_build_service.utils.validate_koji_tag(['tag_name', 'parent_tags'])
     def _koji_add_many_tag_inheritance(self, tag_name, parent_tags):
         tag = self._get_tag(tag_name)
         # highest priority num is at the end
@@ -826,8 +825,7 @@ chmod 644 %buildroot/%_rpmconfigdir/macros.d/macros.modules
 
             self.koji_session.packageListAdd(self.module_tag['name'], package, owner)
 
-    @module_build_service.utils.validate_koji_tag('build_tag')
-    @module_build_service.utils.validate_koji_tag('dest_tag')
+    @module_build_service.utils.validate_koji_tag(['build_tag', 'dest_tag'])
     def _koji_add_target(self, name, build_tag, dest_tag):
         """
         :param name: target name

module_build_service/utils.py

@@ -784,7 +784,7 @@ def get_reusable_component(session, module, component_name):
     return None
 
 
-def validate_koji_tag(tag_arg_name, pre='', post='-', dict_key='name'):
+def validate_koji_tag(tag_arg_names, pre='', post='-', dict_key='name'):
     """
     Used as a decorator validates koji tag arg value (which may be str or list)
     against configurable list of koji tag prefixes.
@@ -794,33 +794,56 @@ def validate_koji_tag(tag_arg_name, pre='', post='-', dict_key='name'):
     tag prefix.
     :param dict_key: In case of a dict arg, inspect this key ('name' by default).
     """
+
+    if not isinstance(tag_arg_names, list):
+        tag_arg_names = [tag_arg_names]
+
     def validation_decorator(function):
         def wrapper(*args, **kwargs):
             call_args = inspect.getcallargs(function, *args, **kwargs)
-            if tag_arg_name not in call_args:
-                raise ProgrammingError(
-                    'Koji tag validation: Inspected argument {} is not within function args.'
-                    ' The function was: {}.'
-                    .format(tag_arg_name, function.__name__))
-            if isinstance(call_args[tag_arg_name], dict):
-                if dict_key not in call_args[tag_arg_name]:
+
+            for tag_arg_name in tag_arg_names:
+
+                # If any of them don't appear in the function, then fail.
+                if tag_arg_name not in call_args:
                     raise ProgrammingError(
-                        'Koji tag validation: Inspected dict arg {} does not contain {} key.'
+                        'Koji tag validation: Inspected argument {} is not within function args.'
                         ' The function was: {}.'
-                        .format(call_args[tag_arg_name], dict_key, function.__name__))
-                tag_list = [call_args[tag_arg_name][dict_key]]
-            elif isinstance(call_args[tag_arg_name], list):
-                tag_list = call_args[tag_arg_name]
-            else:
-                tag_list = [call_args[tag_arg_name]]
-            for tag_prefix in conf.koji_tag_prefixes:
-                if all([t.startswith(pre + tag_prefix + post) for t in tag_list]):
-                    break
-            else:
-                raise ValidationError(
-                    'Koji tag validation: {} does not satisfy any of allowed prefixes: {}'
-                    .format(tag_list,
-                            [pre + p + post for p in conf.koji_tag_prefixes]))
+                        .format(tag_arg_name, function.__name__))
+
+                # If any of them are a dict, then use the provided dict_key
+                if isinstance(call_args[tag_arg_name], dict):
+                    if dict_key not in call_args[tag_arg_name]:
+                        raise ProgrammingError(
+                            'Koji tag validation: Inspected dict arg {} does not contain {} key.'
+                            ' The function was: {}.'
+                            .format(call_args[tag_arg_name], dict_key, function.__name__))
+                    tag_list = [call_args[tag_arg_name][dict_key]]
+                elif isinstance(call_args[tag_arg_name], list):
+                    tag_list = call_args[tag_arg_name]
+                else:
+                    tag_list = [call_args[tag_arg_name]]
+
+                # Check to make sure the provided values match our whitelist.
+                for allowed_prefix in conf.koji_tag_prefixes:
+                    if all([t.startswith(pre + allowed_prefix + post) for t in tag_list]):
+                        break
+                else:
+                    # Only raise this error if the given tags don't start with
+                    # *any* of our allowed prefixes.
+                    raise ValidationError(
+                        'Koji tag validation: {} does not satisfy any of allowed prefixes: {}'
+                        .format(tag_list,
+                                [pre + p + post for p in conf.koji_tag_prefixes]))
+
+            # Finally.. after all that validation, call the original function
+            # and return its value.
             return function(*args, **kwargs)
+
+        # We're replacing the original function with our synthetic wrapper,
+        # but dress it up to make it look more like the original function.
+        wrapper.__name__ = function.__name__
+        wrapper.__doc__ = function.__doc__
         return wrapper
+
     return validation_decorator

tests/test_utils/test_utils.py

@@ -233,3 +233,25 @@ class TestUtils(unittest.TestCase):
         self.assertEquals(
             validate_koji_tag_good_tag_value_in_dict_nondefault_key(
                {'nondefault': 'module-foo'}), True)
+
+    def test_validate_koji_tag_double_trouble_good(self):
+        """ Test that we pass on a list of tags that are good. """
+
+        expected = 'foo'
+
+        @module_build_service.utils.validate_koji_tag(['tag_arg1', 'tag_arg2'])
+        def validate_koji_tag_double_trouble(tag_arg1, tag_arg2):
+            return expected
+
+        actual = validate_koji_tag_double_trouble('module-1', 'module-2')
+        self.assertEquals(actual, expected)
+
+    def test_validate_koji_tag_double_trouble_bad(self):
+        """ Test that we fail on a list of tags that are bad. """
+
+        @module_build_service.utils.validate_koji_tag(['tag_arg1', 'tag_arg2'])
+        def validate_koji_tag_double_trouble(tag_arg1, tag_arg2):
+            pass
+
+        with self.assertRaises(ValidationError):
+            validate_koji_tag_double_trouble('module-1', 'BADNEWS-2')