Verify delete security group response of V2 API

This patch adds the JSON schema for response status of Nova security group
delete API to block the backward incompatibility change in the future.

delete security group does not return the response body.
Response status of this API is 202.

Partially implements blueprint nova-api-attribute-test

Change-Id: I8ce635dfdb41cacaf433b7e14f0fe3b798ef839a
diff --git a/tempest/api_schema/compute/v2/security_groups.py b/tempest/api_schema/compute/v2/security_groups.py
index 8b4bead..9a852e5 100644
--- a/tempest/api_schema/compute/v2/security_groups.py
+++ b/tempest/api_schema/compute/v2/security_groups.py
@@ -80,6 +80,10 @@
     }
 }
 
+delete_security_group = {
+    'status_code': [202]
+}
+
 create_security_group_rule = {
     'status_code': [200],
     'response_body': {
diff --git a/tempest/services/compute/json/security_groups_client.py b/tempest/services/compute/json/security_groups_client.py
index c19baf3..a86f3df 100644
--- a/tempest/services/compute/json/security_groups_client.py
+++ b/tempest/services/compute/json/security_groups_client.py
@@ -88,7 +88,10 @@
 
     def delete_security_group(self, security_group_id):
         """Deletes the provided Security Group."""
-        return self.delete('os-security-groups/%s' % str(security_group_id))
+        resp, body = self.delete(
+            'os-security-groups/%s' % str(security_group_id))
+        self.validate_response(schema.delete_security_group, resp, body)
+        return resp, body
 
     def create_security_group_rule(self, parent_group_id, ip_proto, from_port,
                                    to_port, **kwargs):