add validator for poll_answers

lib/diaspora_federation/validators/poll_validator.rb

@@ -6,6 +6,7 @@ module DiasporaFederation
 
       rule :guid, :guid
       rule :question, [:not_empty, length: {maximum: 255}]
+      rule :poll_answers, length: {minimum: 2}
     end
   end
 end

spec/lib/diaspora_federation/validators/poll_validator_spec.rb

@@ -17,5 +17,18 @@ module DiasporaFederation
         let(:correct_values) { ["a" * 255] }
       end
     end
+
+    describe "#poll_answers" do
+      it_behaves_like "a property with a value validation/restriction" do
+        let(:property) { :poll_answers }
+        let(:wrong_values) { [nil, [FactoryGirl.attributes_for(:poll_answer_entity)]] }
+        let(:correct_values) {
+          [
+            Array.new(2) { FactoryGirl.build(:poll_answer_entity) },
+            Array.new(5) { FactoryGirl.build(:poll_answer_entity) }
+          ]
+        }
+      end
+    end
   end
 end