'Add roles to a user on a tenant.
For a full list of available parameters, please refer to the official
API reference:
https://developer.openstack.org/api-ref/identity/v2-ext/index.html#grant-roles-to-user-on-tenant'

def create_user_role_on_project(self, tenant_id, user_id, role_id):

    (resp, body) = self.put(('/tenants/%s/users/%s/roles/OS-KSADM/%s' % (tenant_id, user_id, role_id)), '')
    self.expected_success(200, resp.status)
    body = json.loads(body)
    return rest_client.ResponseBody(resp, body)
