Originator::createMemento PHP Method

    public function createMemento()
    {
        // 创建备忘录
        return new Memento($this->_state);
    }

 public function testMemento()
 {
     $originator = new Originator();
     $caretaker = new Caretaker();
     $originator->state = "On";
     $caretaker->memento = $originator->createMemento();
     $originator->state = "Off";
     $originator->setMemento($caretaker->memento);
     $this->assertEquals($originator->state, 'On');
 }