Champ: export multiple_drop_down_list as a [].join(', ')

app/models/champ.rb

@@ -77,6 +77,8 @@ class Champ < ActiveRecord::Base
         ActionView::Base.full_sanitizer.sanitize(value)
       when 'yes_no'
         value == 'yes' ? 'oui' : 'non'
+      when 'multiple_drop_down_list'
+        drop_down_list.selected_options_without_decorator(self).join(', ')
       else
         value
       end

spec/models/champ_spec.rb

@@ -99,5 +99,14 @@ describe Champ do
         it { expect(champ.for_export).to eq('non') }
       end
     end
+
+    context 'when type_de_champ is multiple_drop_down_list' do
+      let(:type_champ) { 'multiple_drop_down_list' }
+      let(:value) { '["Crétinier", "Mousserie"]' }
+
+      before { type_de_champ.drop_down_list = create(:drop_down_list) }
+
+      it { expect(champ.for_export).to eq('Crétinier, Mousserie') }
+    end
   end
 end