I try to keep some script to do everything, just in case i get to lazy to do it again by hand, which is … always 🙂

This will install RailsTidy from your Rails directory:
(Ubuntu 7.10) change the paths according to your system

sudo apt-get install tidy
sudo gem install tidy

wget http://www.cosinux.org/~dam/projects/rails-tidy/rails_tidy-0.2/tidy.patch
sudo patch /var/lib/gems/1.8/gems/tidy-1.1.2/lib/tidy/tidybuf.rb < tidy.patch
rm tidy.patch

#script/plugin/install fails with strange warnings and does not install anything...
cd vendor/plugins/
wget http://www.cosinux.org/~dam/projects/rails-tidy/rails_tidy-0.2.tar.bz2
tar -xf rails_tidy-0.2.tar.bz2
rm rails_tidy-0.2.tar.bz2
 
 
 

In case you see something like “tidybuf.rb:39: [BUG] Segmentation fault” downgrade to the last stable version:
apt-get install libtidy-0.99.0/20051018-1 (Ubuntu 8.0.4)

now, inside test_helper.rb you can put this:

class Test::Unit::TestCase
  def teardown
    assert_tidy if @request
  end
end

happy nagging 🙂

PS:
If this is still not enought validating fun for you, you can go a step further with html_test (requires RailsTidy) a project that combines html validation with url checking(do all my links return :success or :redirect?)(Project).