class XMLSerializer {
    public function serialize($object) {
        $document = new DomDocument();
        $root = $document->createElement('object');
        $document->appendChild($root);

        foreach ($object as $key => $value) {
            $root->appendChild($document->createElement($key,$value);
        }

        return $document->saveXML();
    }

    public function unserialze($xml) {
        $document = new DomDocument();
        $document->loadXML($xml);

        $root = $document->getElementsByTagName('root')->item(0);

        $object = new stdclass;
        for ($i = 0; $i < $root->childNodes->length; $i++) {
            $element = $root->childNodes->item($i);
            $tagName = $element->tagName;
            $object->$tagName = $element->nodeValue();
        }

        return $object;
    }

}

如何隔离测试？测试这个类时,我也在测试DomDocument类

我可以传递文档对象：

class XMLSerializer {
    private $document;

    public function __construct(\DomDocument $document) {
        $this->document = $document;
    }

    public function serialize($object) {
        $root = $this->document->createElement('object');
        $this->document->appendChild($root);

        foreach ($object as $key => $value) {
            $root->appendChild($this->document->createElement($key,$value);
        }

        return $this->document->saveXML();
    }

    public function unserialze($xml) {
        $this->document->loadXML($xml);

        $root = $this->document->getElementsByTagName('root')->item(0);

        $object = new stdclass;
        for ($i = 0; $i < $root->childNodes->length; $i++) {
            $element = $root->childNodes->item($i);
            $tagName = $element->tagName;
            $object->$tagName = $element->nodeValue();
        }

        return $object;
    }

}

这似乎解决了这个问题,但是现在我的测试并没有真的做任何事情.我需要做一个模拟的DomDocument返回我在测试中测试的XML：

$object = new stdclass;
$object->foo = 'bar';

$mockDocument = $this->getMock('document')
                ->expects($this->once())
                ->method('saveXML')
                ->will(returnValue('<?xml verison="1.0"?><root><foo>bar</foo></root>'));

$serializer = new XMLSerializer($mockDocument);

$serializer->serialize($object);

哪个有几个问题：

>我实际上并没有测试这个方法,所有我检查的是该方法返回$document-> saveXML()的结果,
>测试意识到方法的实现(它使用domdocument来生成xml)
>如果类重写为使用simplexml或另一个xml库,即使可以产生正确的结果,测试也将失败

所以我可以隔离测试这个代码？看起来我不能..这种类型的依赖关系的名称不能被嘲笑,因为它的行为本质上是被测试的方法所必需的？