UTF-X is a unit testing framework for XSLT. UTF-X strongly supports the test-first-design principle with test rendition and test validation features allowing you to visually design your test before you start working on the stylesheet. UTF-X was originally built to test XSLT stylesheets used in an XML publishing system so it has good support for DTD validation, XHTML and XSL:FO stylesheets.
Although still in alpha releases, UTF-X has been used in real, large projects since 2004.
Latest version of UTF-X is 0.0.8