easy-going-rails/app/helpers/fa_icon_helper.rb

# Font Awesome Helper
module FaIconHelper
  # accept name without 'fa-' prefix, style: (solid by default), size:, class: and 'aria-hidden':
  def fa_icon(name, html_options = {})
    html_options[:style] ||= :solid
    html_options['aria-hidden'] ||= true

    content_class = "fa-#{to_dash(html_options[:style])} fa-#{to_dash(name)}"
    content_class << " fa-#{to_dash(html_options[:size])}" if html_options.key? :size
    content_class << " #{html_options[:class]}" if html_options.key? :class

    tag.i(class: content_class, 'aria-hidden': html_options['aria-hidden'])
  end

  private

  def to_dash(symbol) = symbol.to_s.dasherize
end