Refactor Plan.deep_copy(plan)

app/models/plan.rb

@@ -257,11 +257,9 @@ def self.deep_copy(plan)
     plan_copy.save!
     # Copy newly generated Id to the identifier
     plan_copy.identifier = plan_copy.id.to_s
-    plan.save!
     plan.answers.each do |answer|
       answer_copy = Answer.deep_copy(answer)
-      answer_copy.plan_id = plan_copy.id
-      answer_copy.save!
+      plan_copy.answers << answer_copy
     end
     plan.guidance_groups.each do |guidance_group|
       plan_copy.guidance_groups << guidance_group if guidance_group.present?

spec/models/plan_spec.rb

@@ -398,6 +398,10 @@
       expect(subject.title).to include(plan.title)
     end
 
+    it "copies the new plan's id to its identifer" do
+      expect(subject.identifier).to eql(subject.id.to_s)
+    end
+
     it 'persists the record' do
       expect(subject).to be_persisted
     end