thoughtbot--shoulda-matchers/spec/support/unit/helpers/i18n_faker.rb

module UnitTests
  module I18nFaker
    extend self

    def self.configure_example_group(example_group)
      example_group.include(self)
    end

    def stubbing_translations(translations)
      stub_translations(translations)
      yield
    ensure
      I18n.backend.reload!
      I18n.backend.send(:init_translations)
    end

    def stub_translations(translations)
      translations.each do |key, message|
        stub_translation(key, message)
      end
    end

    def stub_translation(key_or_keys, message)
      keys = [key_or_keys].flatten.join('.').split('.')
      tree = keys.reverse.inject(message) { |data, key| { key => data } }
      I18n.backend.store_translations(:en, tree)
    end
  end
end