This filter hook set the default locale for the filtered examples to get the correct path helpers.

For example the route:

scope "(:locale)" do
  get "xxx/:id", to: "xxx#show", as: :xxx
end

The helper for this route is for example:

xxx_path(1)

This helper will work in rails app in other than test envs, but not in test mode, because “1” will be assigned to :locale and not to :id, and it will complain from not having :id set.

The only solution I found is to stub ActionController::Base.default_url_options.

https://gist.github.com/ubugnu/1a57103b90c32991f4e512d47d9e1561