Add additional assertions for volume transfer test

When a transferred volume is accepted by another user in different
tenant, the user and tenant of the volume should be changed. This
patch is to add explicit assertions for these two attributes in
volume transfer test.

Change-Id: Iaaee981c5d0c17133cc426479904c584e28f8578
diff --git a/tempest/api/volume/test_volume_transfers.py b/tempest/api/volume/test_volume_transfers.py
index 5fd1904..5a192ac 100644
--- a/tempest/api/volume/test_volume_transfers.py
+++ b/tempest/api/volume/test_volume_transfers.py
@@ -63,6 +63,12 @@
             transfer_id, auth_key=auth_key)['transfer']
         waiters.wait_for_volume_resource_status(self.alt_volumes_client,
                                                 volume['id'], 'available')
+        accepted_volume = self.alt_volumes_client.show_volume(
+            volume['id'])['volume']
+        self.assertEqual(self.os_alt.credentials.user_id,
+                         accepted_volume['user_id'])
+        self.assertEqual(self.os_alt.credentials.project_id,
+                         accepted_volume['os-vol-tenant-attr:tenant_id'])
 
     @decorators.idempotent_id('ab526943-b725-4c07-b875-8e8ef87a2c30')
     def test_create_list_delete_volume_transfer(self):