Validate (X)HTML and CSS in Rails functional tests

With a handy plugin written by Peter Donald, you can validate (X)HTML and CSS in your Rails functional tests.The plugin requires the XmlSimple gem. Make sure to install it:

sudo gem install xml-simple

Then, in your functional tests, you can write:

test "valid markup" do
  get :index
  assert_valid_markup
end

Unfortunately, the plugin broke somewhere around Rails 2.3.x, but I figured out how to fix it pretty fast. Here’s what made it work for me. Continue reading »