'Check role of a group on a project.'

def check_role_from_group_on_project_existence(self, project_id, group_id, role_id):

    (resp, body) = self.head(('projects/%s/groups/%s/roles/%s' % (project_id, group_id, role_id)))
    self.expected_success(204, resp.status)
    return rest_client.ResponseBody(resp)
