discourse/db/fixtures/502_staff_category.rb

unless Rails.env.test?
  staff = Category.where(id: SiteSetting.staff_category_id).first
  if staff and !staff.group_ids.include?(Group[:staff].id)

    # Add permissions and a description to the Staff category.

    staff.group_names = ['staff']
    unless staff.save
      puts staff.errors.full_messages
      raise "Failed to set permissions on the Staff category!"
    end

    if staff.topic_id.nil?
      creator = PostCreator.new(Discourse.system_user,
        raw: I18n.t('staff_category_description'),
        title: I18n.t('category.topic_prefix', category: staff.name),
        category: staff.name,
        archetype: Archetype.default
      )
      post = creator.create

      unless post && post.id
        puts post.errors.full_messages if post
        puts creator.errors.inspect
        raise "Failed to create description for Staff category!"
      end

      staff.topic_id = post.topic.id
      unless staff.save
        puts staff.errors.full_messages
        puts "Failed to set the Staff category description topic!"
      end

      # Reset topic count because we don't count the description topic
      Category.exec_sql "UPDATE categories SET topic_count = 0 WHERE id = #{staff.id}"
    end
  end
end