Overwrite `t` helper in Rails views to raise in tests, which it otherwise doesn't do, even if I18n is configured to.

lib-i18n_raise_on_missing_in_action_view.rb

# Overwrite `t` helper in Rails views to raise in tests,
# which it otherwise doesn't do, even if I18n is configured to.
#
# Installation:
# put in lib/i18n_raise_on_missing_in_action_view.rb
# and require "i18n_raise_on_missing_in_action_view" in e.g. config/environments/test.rb

if Rails.env.test?
  module ActionView::Helpers::TranslationHelper
    def t_with_raise(*args)
      value = t_without_raise(*args)

      if value.to_s.match(/title="translation missing: (.+)"/)
        raise "Translation missing: #{$1}"
      else
        value
      end
    end
    alias_method :translate_with_raise, :t_with_raise

    alias_method_chain :t, :raise
    alias_method_chain :translate, :raise
  end
end