Don't use default mutable parameter

Using default mutable parameter is bad.
Default parameters are evaluated only once
if you mutate it you will get unexpected results.
Since we don't mutate here the default paramter, make
sure it is unmutable.

Change-Id: Ib5c451a8c8cad7b6c9a009369c1c039563023368

mistral/actions/openstack/action_generator/base.py

@@ -70,7 +70,7 @@ class OpenStackActionGenerator(action_generator.ActionGenerator):
     base_action_class = None
 
     @classmethod
-    def prepare_action_inputs(cls, origin_inputs, added=[]):
+    def prepare_action_inputs(cls, origin_inputs, added=()):
         """Modify action input string.
 
         Sometimes we need to change the default action input definition for

mistral/api/hooks/content_type.py

@@ -16,7 +16,7 @@ from pecan import hooks
 
 
 class ContentTypeHook(hooks.PecanHook):
-    def __init__(self, content_type, methods=['GET']):
+    def __init__(self, content_type, methods=('GET',)):
         """Content type hook.
 
         This hook is needed for changing content type of

mistral/lang/base.py

@@ -158,7 +158,7 @@ class BaseSpec(object):
     _version = '2.0'
 
     @classmethod
-    def get_schema(cls, includes=['meta', 'definitions']):
+    def get_schema(cls, includes=('meta', 'definitions')):
         schema = copy.deepcopy(cls._schema)
 
         schema['properties'] = utils.merge_dicts(

mistral/lang/v2/on_clause.py

@@ -107,7 +107,7 @@ class OnClauseSpec(base.BaseSpec):
             self._next = prepare_next_clause(data.get('next'))
 
     @classmethod
-    def get_schema(cls, includes=['definitions']):
+    def get_schema(cls, includes=('definitions',)):
         return super(OnClauseSpec, cls).get_schema(includes)
 
     def get_publish(self):

mistral/lang/v2/policies.py

@@ -34,7 +34,7 @@ class PoliciesSpec(base.BaseSpec):
     }
 
     @classmethod
-    def get_schema(cls, includes=['definitions']):
+    def get_schema(cls, includes=('definitions',)):
         return super(PoliciesSpec, cls).get_schema(includes)
 
     def __init__(self, data, validate):

mistral/lang/v2/publish.py

@@ -37,7 +37,7 @@ class PublishSpec(base.BaseSpec):
         self._atomic = self._data.get('atomic')
 
     @classmethod
-    def get_schema(cls, includes=['definitions']):
+    def get_schema(cls, includes=('definitions',)):
         return super(PublishSpec, cls).get_schema(includes)
 
     def validate_semantics(self):

mistral/lang/v2/retry_policy.py

@@ -51,7 +51,7 @@ class RetrySpec(base.BaseSpec):
     }
 
     @classmethod
-    def get_schema(cls, includes=['definitions']):
+    def get_schema(cls, includes=('definitions',)):
         return super(RetrySpec, cls).get_schema(includes)
 
     def __init__(self, data, validate):

mistral/lang/v2/task_defaults.py

@@ -50,7 +50,7 @@ class TaskDefaultsSpec(base.BaseSpec):
     }
 
     @classmethod
-    def get_schema(cls, includes=['definitions']):
+    def get_schema(cls, includes=('definitions',)):
         return super(TaskDefaultsSpec, cls).get_schema(includes)
 
     def __init__(self, data, validate):