tests: Convert identity tests to use 'parse_output'

Change-Id: I10711b911986af0348946f6254cf36773110b0ab

Author: stephenfin

openstackclient/tests/functional/identity/v3/test_project.py

@@ -10,8 +10,6 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import json
-
 from tempest.lib.common.utils import data_utils
 
 from openstackclient.tests.functional.identity.v3 import common
@@ -114,12 +112,14 @@ def test_project_show(self):
         self.assert_show_fields(items, self.PROJECT_FIELDS)
 
     def test_project_show_with_parents_children(self):
-        json_output = json.loads(self.openstack(
+        output = self.openstack(
             'project show '
-            '--parents --children -f json '
+            '--parents --children '
             '--domain %(domain)s '
             '%(name)s' % {'domain': self.domain_name,
-                          'name': self.project_name}))
+                          'name': self.project_name},
+            parse_output=True,
+        )
         for attr_name in (self.PROJECT_FIELDS + ['parents', 'subtree']):
-            self.assertIn(attr_name, json_output)
-        self.assertEqual(self.project_name, json_output.get('name'))
+            self.assertIn(attr_name, output)
+        self.assertEqual(self.project_name, output.get('name'))