testtools.py 文件源码

def lxml(self):
        """Get an lxml etree if possible."""
        if ('html' not in self.mimetype and 'xml' not in self.mimetype):
            raise AttributeError('Not an HTML/XML response')
        from lxml import etree
        try:
            from lxml.html import fromstring
        except ImportError:
            fromstring = etree.HTML
        if self.mimetype == 'text/html':
            return fromstring(self.data)
        return etree.XML(self.data)