i18n_check.rb

#!/usr/bin/env ruby

# taken from tolk
PLURALIZATION_KEYS = ['zero', 'one', 'two', 'few', 'many', 'other']
def pluralization_data?(data)
  keys = data.keys.map(&:to_s)
  keys.all? {|k| PLURALIZATION_KEYS.include?(k) }
end

def flat_hash(data, prefix = '', result = {})
  data.each do |key, value|
    current_prefix = prefix.present? ? "#{prefix}.#{key}" : key

    if !value.is_a?(Hash)
      result[current_prefix] = value.respond_to?(:stringify_keys) ? value.stringify_keys : value
    elsif pluralization_data?(value)
      result[current_prefix] = value.respond_to?(:stringify_keys) ? value.stringify_keys : value
    else
      flat_hash(value, current_prefix, result)
    end
  end

  result.stringify_keys
end


I18n.locale = :en
I18n.t :hoge

translations = flat_hash I18n.backend.instance_variable_get('@translations')[:en]

I18n.locale = :ja
translations.each do |key, value|
  # trash
  next if key == 'hello'
  # useless for Japanese
  next if key =~ /^number.human.decimal_units/
  p key
  I18n.t key, :raise => true
end