Flash Messages, System Messages, Ruby on Rails, by style, debug and test

controller:

flash[:notice] = "Correct things."
flash[:error]  = "Alert things."
flash[:debug]  = "Simple debug."

views/layouts:

<%- flash.each do |name, msg| -%>
  <%= content_tag :div, msg, :id => "flash_#{name}" %>
<%- end -%>

css out of dev, in test, this can help you in both environments:

#debug{
  display:none;
}