missing_keys.rb

module I18n
  def self.missing_keys
    @missing_keys
  end

  def self.t(*args, &block)
    opts = args.dup.extract_options!
    opts[:default] = Array(opts[:default]).delete_if do |d|
      d.is_a? String
    end
    if super(*args, opts) =~ /missing/
      @missing_keys ||= []
      @missing_keys << [opts[:scope].to_s, args.first.to_s].select(&:present?).join(".")
    end

    super
  end
end

RSpec.configure do |config|
  config.after(:suite) do
    puts I18n.missing_keys.uniq.sort.to_yaml
  end
end