Set the default locale in config (#6580)

Previously the default locale was set by Localized concern for controllers,
but it was not enforced for mailers.

config is enforced throughout the application and an appropriate place to
set the default locale.

app/controllers/concerns/localized.rb

@@ -17,11 +17,7 @@ module Localized
   end
 
   def default_locale
-    request_locale || env_locale || I18n.default_locale
-  end
-
-  def env_locale
-    ENV['DEFAULT_LOCALE']
+    request_locale || I18n.default_locale
   end
 
   def request_locale
@@ -29,12 +25,10 @@ module Localized
   end
 
   def preferred_locale
-    http_accept_language.preferred_language_from([env_locale]) ||
     http_accept_language.preferred_language_from(I18n.available_locales)
   end
 
   def compatible_locale
-    http_accept_language.compatible_language_from([env_locale]) ||
     http_accept_language.compatible_language_from(I18n.available_locales)
   end
 end

config/application.rb

@@ -31,7 +31,7 @@ module Mastodon
     # Run "rake -D time" for a list of tasks for finding time zone names. Default is UTC.
     # config.time_zone = 'Central Time (US & Canada)'
 
-    # The default locale is :en and all translations from config/locales/*.rb,yml are auto loaded.
+    # All translations from config/locales/*.rb,yml are auto loaded.
     # config.i18n.load_path += Dir[Rails.root.join('my', 'locales', '*.{rb,yml}').to_s]
     config.i18n.available_locales = [
       :en,
@@ -73,7 +73,12 @@ module Mastodon
       :'zh-TW',
     ]
 
+    config.i18n.default_locale = ENV['DEFAULT_LOCALE']&.to_sym
+    if config.i18n.available_locales.include?(config.i18n.default_locale)
+      config.i18n.fallbacks = [:en]
+    else
       config.i18n.default_locale = :en
+    end
 
     # config.paths.add File.join('app', 'api'), glob: File.join('**', '*.rb')
     # config.autoload_paths += Dir[Rails.root.join('app', 'api', '*')]

config/environments/test.rb

@@ -51,6 +51,9 @@ Rails.application.configure do
 
   # Raises error for missing translations
   # config.action_view.raise_on_missing_translations = true
+
+  config.i18n.default_locale = :en
+  config.i18n.fallbacks = true
 end
 
 Paperclip::Attachment.default_options[:path] = "#{Rails.root}/spec/test_files/:class/:id_partition/:style.:extension"

spec/controllers/concerns/localized_spec.rb

@@ -16,51 +16,26 @@ describe ApplicationController, type: :controller do
   end
 
   shared_examples 'default locale' do
-    context 'when DEFAULT_LOCALE environment variable is set' do
-      around do |example|
-        ClimateControl.modify 'DEFAULT_LOCALE' => 'ca', &example.method(:run)
-        I18n.locale = I18n.default_locale
-      end
-
-      it 'sets language specified by ENV if preferred' do
-        request.headers['Accept-Language'] = 'ca, fa'
-        get 'success'
-        expect(I18n.locale).to eq :ca
-      end
+    after { I18n.locale = I18n.default_locale }
 
-      it 'sets available and preferred language if language specified by ENV is not preferred' do
+    it 'sets available and preferred language' do
       request.headers['Accept-Language'] = 'ca-ES, fa'
       get 'success'
       expect(I18n.locale).to eq :fa
     end
 
-      it 'sets language specified by ENV if it is compatible and none of available languages are preferred' do
-        request.headers['Accept-Language'] = 'ca-ES, fa-IR'
-        get 'success'
-        expect(I18n.locale).to eq :ca
-      end
-
-      it 'sets available and compatible langauge if language specified by ENV is not compatible none of available languages are preferred' do
+    it 'sets available and compatible langauge if none of available languages are preferred' do
       request.headers['Accept-Language'] = 'fa-IR'
       get 'success'
       expect(I18n.locale).to eq :fa
     end
 
-      it 'sets language specified by ENV if none of available languages are compatible' do
-        request.headers['Accept-Language'] = ''
-        get 'success'
-        expect(I18n.locale).to eq :ca
-      end
-    end
-
-    context 'when DEFAULT_LOCALE environment variable is not set' do
     it 'sets default locale if none of available languages are compatible' do
       request.headers['Accept-Language'] = ''
       get 'success'
       expect(I18n.locale).to eq :en
     end
   end
-  end
 
   context 'user with valid locale has signed in' do
     it "sets user's locale" do