Testcase to create domain without description

This submission adds "test_create_domain_without_description"
testcase to test_domains.py.

Change-Id: I3ab22f6dc9505a7e2e65d40af30cec7276efba31
diff --git a/tempest/api/identity/admin/v3/test_domains.py b/tempest/api/identity/admin/v3/test_domains.py
index 1f6e651..2ae687c 100644
--- a/tempest/api/identity/admin/v3/test_domains.py
+++ b/tempest/api/identity/admin/v3/test_domains.py
@@ -96,3 +96,15 @@
         self.assertEqual(d_name, domain['name'])
         self.assertFalse(domain['enabled'])
         self.assertEqual(d_desc, domain['description'])
+
+    @test.attr(type='smoke')
+    @test.idempotent_id('2abf8764-309a-4fa9-bc58-201b799817ad')
+    def test_create_domain_without_description(self):
+        # Create domain only with name
+        d_name = data_utils.rand_name('domain-')
+        domain = self.client.create_domain(d_name)
+        self.addCleanup(self._delete_domain, domain['id'])
+        self.assertIn('id', domain)
+        expected_data = {'name': d_name, 'enabled': True}
+        self.assertIsNone(domain['description'])
+        self.assertDictContainsSubset(expected_data, domain)