Fix use the fact that empty sequences are false.

For sequences(strings, lists, tuples), in order to consistent with
pep8 recommendations, 'if len(seq)' should be replaced with 'if seq',
and 'if not len(seq)' should be replaced with 'if not seq'.

Change-Id: Ieb2c90b7f87b54361a2c291a838550227fde9fbe
Closes-Bug: #1156472

keystone/assignment/backends/kvs.py

@@ -141,7 +141,7 @@ class Assignment(kvs.Base, assignment.Driver):
                 'Cannot remove role that has not been granted, %s') %
                 role_id)
 
-        if len(metadata_ref['roles']):
+        if metadata_ref['roles']:
             self._update_metadata(user_id, tenant_id, metadata_ref)
         else:
 

keystone/assignment/backends/sql.py

@@ -341,7 +341,7 @@ class Assignment(sql.Base, assignment.Driver):
                     'Cannot remove role that has not been granted, %s') %
                     role_id)
 
-            if len(metadata_ref['roles']):
+            if metadata_ref['roles']:
                 self._update_metadata(session, user_id, tenant_id,
                                       metadata_ref)
             else:

keystone/auth/controllers.py

@@ -399,7 +399,7 @@ class Auth(controller.V3Controller):
                 auth_response['methods'].append(method_name)
                 auth_response[method_name] = resp
 
-        if len(auth_response["methods"]) > 0:
+        if auth_response["methods"]:
             # authentication continuation required
             raise exception.AdditionalAuthRequired(auth_response)
 

keystone/auth/plugins/oauth1.py

@@ -71,7 +71,7 @@ class OAuth(auth.AuthMethodHandler):
                                              consumer_obj,
                                              token=acc_token_obj)
 
-        if len(params) != 0:
+        if params:
             msg = _('There should not be any non-oauth parameters')
             raise exception.Unauthorized(message=msg)
 

keystone/common/controller.py

@@ -195,7 +195,7 @@ def filterprotected(*filters):
                 #
                 # First  any query filter parameters
                 target = dict()
-                if len(filters) > 0:
+                if filters:
                     for item in filters:
                         if item in context['query_string']:
                             target[item] = context['query_string'][item]

keystone/common/serializer.py

@@ -125,7 +125,7 @@ class XmlDeserializer(object):
         values = values or text or {}
         decoded_tag = XmlDeserializer._qualified_name(element.tag, namespace)
         list_item_tag = None
-        if (decoded_tag[-1] == 's' and len(values) == 0 and
+        if (decoded_tag[-1] == 's' and not values and
                 decoded_tag != 'access'):
             # FIXME(gyee): special-case lists for now unti we
             # figure out how to properly handle them.

keystone/contrib/endpoint_filter/backends/catalog_sql.py

@@ -33,7 +33,7 @@ class EndpointFilterCatalog(sql.Catalog):
 
         refs = self.endpoint_filter_api.list_endpoints_for_project(project_id)
 
-        if (len(refs) == 0 and
+        if (not refs and
                 CONF.endpoint_filter.return_all_endpoints_if_no_filter):
             return super(EndpointFilterCatalog, self).get_v3_catalog(
                 user_id, project_id, metadata=metadata)

keystone/contrib/oauth1/controllers.py

@@ -265,7 +265,7 @@ class OAuthControllerV3(controller.V3Controller):
                                              consumer_obj,
                                              token=req_token_obj)
 
-        if len(params) != 0:
+        if params:
             msg = _('There should not be any non-oauth parameters')
             raise exception.Unauthorized(message=msg)
 

keystone/tests/fakeldap.py

@@ -280,7 +280,7 @@ class FakeLdap(object):
                 values[:] = _process_attr(k, v)
             elif cmd == ldap.MOD_DELETE:
                 if v is None:
-                    if len(values) == 0:
+                    if not values:
                         LOG.debug(_('FakeLdap modify item failed: '
                                   'item has no attribute "%s" to delete'), k)
                         raise ldap.NO_SUCH_ATTRIBUTE