Test if translation missings?

We have a multilingual application using I18n,
How would you test your application have no translations missings ?
Would you test it view by view ? or have you a better solution ?



My first guess:
When you have view specs or controller specs with
render_views/integrate_views you could make I18n raise an error when
its missing a translation. Then run every spec in every locale and
you’ll see where there are missing. This might be a lot of work and
you won’t get translations that have a default (like

So, my second guess:
You’ll probably have one base locale, the one you work in. If you
consider that one to be complete, you can compare the keys from each
translation. You’ll have to flatten them first though. This isn’t easy

So, I hope you have some ideas from this. Good luck, and share the
answer if you find it :slight_smile:


You can do this to intercept any missing translations when you restart
your app:

module I18n
class << self
def raise_custom_exception(exception, locale, key, options)
if MissingTranslationData === exception
# do something with the missing translation

    return translation
    raise exception


I18n.exception_handler = :raise_custom_exception

I’ve used it to make a call to the google translate API to generate
any missing machine translation(s), and then push them to my backend
so I have them for next time.

Hope that helps!

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Hi Iain,
Thanks for the reply,
I was thinking of the 2nd solution but it fails if we forget
translations in the main language.
I was hoping there’s maybe a way to scan the code via a rake task,
find ALL the keys used in the code and compare them to the one
declared in locales but it’s maybe way more work …
Thanks for your help.


Hey guys thanx for the awesome replies !

Andrs, hope you’re doing good and enjoying France :slight_smile:
You’re right I didn’t think of this cases and we have quite a few in
our app.

Shelly, nice piece of code but as Lawrence said it won’t work if
you’re using a default translation.

Lawrence thanks for pointing me this extension, it seems very nice.
I’ll implement that :slight_smile:


Hi Mike,

That can be done but it won’t help when you have dynamic keys like


Andrs M.

When people ask about missing translations I wonder if they mean missing
lookups instead.

If you do I18n.t(:missing, :default => :not_missing) then you won’t get
into the I18n.exception_handler routine as there is no missing
translation. But there is a missing lookup.

If you use the gettext helpers then by definition there are no missing
translations, only missing lookups.

In the end I came to the conclusion that it is an impossible task to
find missing translations by running or testing the app.

See also: