Here's a sample test/factories.rb:
# Factories
Factory.define :article do |t|
t.association :section # An article belongs to a section
t.title {|x| "#{x.section.name}Article#{Factory.next(:count)}" } # Use brackets when you're calling a sequence
t.author "Author Bob"
# Assuming you have put "require 'forgery' " in the correct place. It could just be in your seeds.rb file.
t.body Forgery::LoremIpsum.paragraphs(5)