assertvalidasset is a plugin to validate your (X)HTML and CSS using the W3C Validator web service (http://validator.w3.org/) and the W3C CSS Validation Service (http://jigsaw.w3.org/css-validator) as part of your functional or unit tests. The css and html fragments are cached in $RAILS_ROOT/tmp/test/assets as are the results from the web service. This means that your tests will not be slowed down unless the output has changed.

The code started life as a few modifications to Scott Raymond's assertvalidmarkup (http://redgreenblu.com/svn/projects/assertvalidmarkup/) and evolved to cache fragments and results in $RAILS_ROOT/tmp/test/assets rather than the system temp directory. Then the ability to validate CSS files was added. I also added the ability to skip checks if the "NONET" environment variable is set to "true".