Add extra elements check for 'show_volume_type' command

Update "test_volume_type_create_get_delete" testcase to verify
'show_volume_type' command according to the following parameters:
'description', 'is_public' and 'os-volume-type-access:is_public'.

Change-Id: I62e77a89321ca36455de4251b13f916483822da0
diff --git a/tempest/api/volume/admin/test_volume_types.py b/tempest/api/volume/admin/test_volume_types.py
index 3d44bbe..3083e0d 100644
--- a/tempest/api/volume/admin/test_volume_types.py
+++ b/tempest/api/volume/admin/test_volume_types.py
@@ -91,8 +91,11 @@
         vendor = CONF.volume.vendor_name
         extra_specs = {"storage_protocol": proto,
                        "vendor_name": vendor}
-        body = self.create_volume_type(description=description, name=name,
-                                       extra_specs=extra_specs)
+        params = {'name': name,
+                  'description': description,
+                  'extra_specs': extra_specs,
+                  'os-volume-type-access:is_public': True}
+        body = self.create_volume_type(**params)
         self.assertIn('name', body)
         self.assertEqual(name, body['name'],
                          "The created volume_type name is not equal "
@@ -113,6 +116,12 @@
         self.assertEqual(extra_specs, fetched_volume_type['extra_specs'],
                          'The fetched Volume_type is different '
                          'from the created Volume_type')
+        self.assertEqual(description, fetched_volume_type['description'])
+        self.assertEqual(body['is_public'],
+                         fetched_volume_type['is_public'])
+        self.assertEqual(
+            body['os-volume-type-access:is_public'],
+            fetched_volume_type['os-volume-type-access:is_public'])
 
     @test.idempotent_id('7830abd0-ff99-4793-a265-405684a54d46')
     def test_volume_type_encryption_create_get_delete(self):