[fix #2956] YesNo: fixing to_s

app/models/champs/yes_no_champ.rb

@@ -5,6 +5,10 @@ class Champs::YesNoChamp < Champs::CheckboxChamp
     end
   end
 
+  def to_s
+    value_for_export
+  end
+
   private
 
   def value_for_export

spec/models/champs/yes_no_champ_spec.rb

@@ -0,0 +1,23 @@
+describe Champs::YesNoChamp do
+  describe '#to_s' do
+    subject { Champs::YesNoChamp.new(value: value).to_s }
+
+    context 'when the value is false' do
+      let(:value) { "false" }
+
+      it { is_expected.to eq("non") }
+    end
+
+    context 'when the value is true' do
+      let(:value) { "true" }
+
+      it { is_expected.to eq("oui") }
+    end
+
+    context 'when the value is nil' do
+      let(:value) { nil }
+
+      it { is_expected.to eq("non") }
+    end
+  end
+end