Fix crash with no translation for default locale

When we were visiting a page showing the content of a record which uses
globalize and our locale was the default one and there was no
translation for the default locale, the application was crashing in some
places because there are no fallbacks for the default locale.

For example, when visiting a legislation process, the line with
`CGI.escape(title)` was crashing because `title` was `nil` for the
default locale.

We've decided to solve this issue by using any available translations as
globalize fallbacks instead of showing a 404 error or a translation
missing error because these solutions would (we thinkg) either require
modifying many places in the application or making the translatable
logic even more complex.

Initially we tried to add this solution to an initializer, but it must
be called after initializing the application so I18n.fallbacks[locale]
gets the value defined in config.i18n.fallbacks.

Also note the line:

fallbacks[locale] = I18n.fallbacks[locale] + I18n.available_locales

Doesn't mention `I18n.default_locale` because the method
`I18n.fallbacks[locale]` automatically adds the default locale.

config/application.rb

@@ -48,6 +48,8 @@ module Consul
     config.i18n.load_path += Dir[Rails.root.join('config', 'locales', '**', '*.{rb,yml}')]
     config.i18n.load_path += Dir[Rails.root.join('config', 'locales', 'custom', '**', '*.{rb,yml}')]
 
+    config.after_initialize { Globalize.set_fallbacks_to_all_available_locales }
+
     config.assets.paths << Rails.root.join("app", "assets", "fonts")
 
     # Do not swallow errors in after_commit/after_rollback callbacks.

config/initializers/globalize.rb

@@ -11,3 +11,9 @@ module Globalize
     end
   end
 end
+
+def Globalize.set_fallbacks_to_all_available_locales
+  Globalize.fallbacks = I18n.available_locales.each_with_object({}) do |locale, fallbacks|
+    fallbacks[locale] = (I18n.fallbacks[locale] + I18n.available_locales).uniq
+  end
+end

spec/features/legislation/processes_spec.rb

@@ -141,6 +141,14 @@ feature 'Legislation' do
 
         expect(page).to_not have_content("Additional information")
       end
+
+      scenario "Shows another translation when the default locale isn't available" do
+        process = create(:legislation_process, title_fr: "Français")
+        process.translations.where(locale: :en).first.destroy
+
+        visit legislation_process_path(process)
+        expect(page).to have_content("Français")
+      end
     end
 
     context 'debate phase' do

spec/models/admin_notification_spec.rb

@@ -3,6 +3,8 @@ require 'rails_helper'
 describe AdminNotification do
   let(:admin_notification) { build(:admin_notification) }
 
+  it_behaves_like "globalizable", :admin_notification
+
   it "is valid" do
     expect(admin_notification).to be_valid
   end

spec/models/concerns/globalizable.rb

@@ -0,0 +1,56 @@
+require "spec_helper"
+
+shared_examples_for "globalizable" do |factory_name|
+  let(:record) { create(factory_name) }
+  let(:field) { record.translated_attribute_names.first }
+
+  describe "Fallbacks" do
+    before do
+      allow(I18n).to receive(:available_locales).and_return(%i[ar de en es fr])
+
+      record.update_attribute(field, "In English")
+
+      { es: "En español", de: "Deutsch" }.each do |locale, text|
+        Globalize.with_locale(locale) do
+          record.translated_attribute_names.each do |attribute|
+            record.update_attribute(attribute, record.send(attribute))
+          end
+
+          record.update_attribute(field, text)
+        end
+      end
+    end
+
+    after do
+      allow(I18n).to receive(:available_locales).and_call_original
+      allow(I18n.fallbacks).to receive(:[]).and_call_original
+      Globalize.set_fallbacks_to_all_available_locales
+    end
+
+    context "With a defined fallback" do
+      before do
+        allow(I18n.fallbacks).to receive(:[]).and_return([:fr, :es])
+        Globalize.set_fallbacks_to_all_available_locales
+      end
+
+      it "Falls back to the defined fallback" do
+        Globalize.with_locale(:fr) do
+          expect(record.send(field)).to eq "En español"
+        end
+      end
+    end
+
+    context "Without a defined fallback" do
+      before do
+        allow(I18n.fallbacks).to receive(:[]).and_return([:fr])
+        Globalize.set_fallbacks_to_all_available_locales
+      end
+
+      it "Falls back to the first available locale" do
+        Globalize.with_locale(:fr) do
+          expect(record.send(field)).to eq "Deutsch"
+        end
+      end
+    end
+  end
+end