Rails: How to raise I18n translation is missing exceptions in the testing environment

As of Rails 4.1.0, there’s now a better solution than the 4 year-old answers to this question: add the following line to your config file:

config.action_view.raise_on_missing_translations = true

I like to set this in the test environment only, but you might also want to set it in development. I would strongly advise against setting it to true in production.