it 'contains only unique display_names, code_names and database_encodings' do
      display_names = Locale.available_locale_preferences.map(&:display_name)
      expect(display_names.uniq.length).to eq(display_names.length)
      code_names = Locale.available_locale_preferences.map(&:code_name)
      expect(code_names.uniq.length).to eq(code_names.length)