public function test_failInsert_event()
{
$user = new Users();
$user->on(Users::EVENT_BEFORE_INSERT, function ($e) {
$e->isValid = false;
});
$user->username = '******';
$user->password = '******';
$user->access_token = 'token';
$user->save();
// failed
$this->assertEmpty(Users::findIdentity($user->username));
}