Prado\Xml\TXmlDocument::saveToString PHP Méthode

    public function saveToString()
    {
        $version = empty($this->_version) ? ' version="1.0"' : ' version="' . $this->_version . '"';
        $encoding = empty($this->_encoding) ? '' : ' encoding="' . $this->_encoding . '"';
        return "<?xml{$version}{$encoding}?>\n" . $this->toString(0);
    }

 public function testSaveToString()
 {
     $xmldoc = new TXmlDocument('1.0', 'utf-8');
     $xmldoc->setTagName('root');
     $node = new TXmlElement('node');
     $node->setAttribute('param', 'attribute1');
     $xmldoc->getElements()->add($node);
     $xmlString = $xmldoc->saveToString();
     // test magic method
     $magicString = (string) $xmldoc;
     self::assertEquals($magicString, $xmlString);
     // Result string should be :
     $resultString = "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n<root>\n    <node param=\"attribute1\"\n</root>";
     self::assertEquals($xmlString, $magicString);
 }