Test html against schema

I have a task to perform html markup test on stage server before deploying project on production.

First of all I was thinking about using xml-schema, which is rather flexible tool, but it works only with well-formed xml documents. So the chain of actions is:

• get piece of html


• pass to php


• use tidy to get xhtml


• match against xml-schema


• return human-readable errors (if any have occured)

Are there any solutions better than above? Thank you.