Port volume backup dashboard to Python 3

Stop using deprecated data_type_singular and data_type_plural:
replace them with action_present and action_past properties to handle
correctly singular/plural.

Partial-Implements: blueprint porting-python3
Change-Id: I4fc3acf2da27348f371d3e387588baafc286605a

openstack_dashboard/dashboards/project/volumes/backups/tables.py

@@ -17,6 +17,7 @@ from django.utils import http
 from django.utils import safestring
 from django.utils.translation import pgettext_lazy
 from django.utils.translation import ugettext_lazy as _
+from django.utils.translation import ungettext_lazy
 
 from horizon import tables
 
@@ -45,11 +46,24 @@ class BackupVolumeNameColumn(tables.Column):
 
 
 class DeleteBackup(tables.DeleteAction):
-    data_type_singular = _("Volume Backup")
-    data_type_plural = _("Volume Backups")
-    action_past = _("Scheduled deletion of %(data_type)s")
     policy_rules = (("volume", "backup:delete"),)
 
+    @staticmethod
+    def action_present(count):
+        return ungettext_lazy(
+            u"Delete Volume Backup",
+            u"Delete Volume Backups",
+            count
+        )
+
+    @staticmethod
+    def action_past(count):
+        return ungettext_lazy(
+            u"Scheduled deletion of Volume Backup",
+            u"Scheduled deletion of Volume Backups",
+            count
+        )
+
     def delete(self, request, obj_id):
         api.cinder.volume_backup_delete(request, obj_id)
 

tox.ini

@@ -38,6 +38,7 @@ commands =
         openstack_dashboard.dashboards.project.networks.tests \
         openstack_dashboard.dashboards.project.overview.tests \
         openstack_dashboard.dashboards.project.stacks \
+        openstack_dashboard.dashboards.project.volumes \
         openstack_dashboard.dashboards.settings.password \
         openstack_dashboard.test.api_tests.base_tests.APIDictWrapperTests \
         openstack_dashboard.test.api_tests.base_tests.APIResourceWrapperTests \