[#1421] Format linked dropdown menus in spreadsheet export

app/models/champs/linked_drop_down_list_champ.rb

@@ -34,6 +34,10 @@ class Champs::LinkedDropDownListChamp < Champ
 
   private
 
+  def value_for_export
+    "#{primary_value || ''};#{secondary_value || ''}"
+  end
+
   def pack_value
     self.value = JSON.generate([ primary_value, secondary_value ])
   end

spec/models/champs/linked_drop_down_list_champ_spec.rb

@@ -40,4 +40,26 @@ describe Champs::LinkedDropDownListChamp do
       it { is_expected.to eq('primary / secondary') }
     end
   end
+
+  describe 'for_export' do
+    subject { champ.for_export }
+
+    context 'with no value' do
+      let(:champ) { described_class.new }
+
+      it { is_expected.to be_nil }
+    end
+
+    context 'with primary value' do
+      let(:champ) { described_class.new(primary_value: 'primary') }
+
+      it { is_expected.to eq('primary;') }
+    end
+
+    context 'with secondary value' do
+      let(:champ) { described_class.new(primary_value: 'primary', secondary_value: 'secondary') }
+
+      it { is_expected.to eq('primary;secondary') }
+    end
+  end
 end