Merge comment with problem during the merge of some problem

see #477

app/interactors/problem_merge.rb

@@ -11,7 +11,9 @@ def initialize(*problems)
 
   def merge
     child_problems.each do |problem|
-      merged_problem.errs.concat Err.where(:problem_id => problem.id)
+      merged_problem.errs.concat problem.errs
+      merged_problem.comments.concat problem.comments
+      problem.reload # deference all associate objet to avoid delete him after
       ProblemDestroy.execute(problem)
     end
     reset_cached_attributes

spec/interactors/problem_merge_spec.rb

@@ -29,6 +29,7 @@
     let(:merged_errs) { problem_1.errs }
     let!(:notice) { Fabricate(:notice, :err => first_errs.first) }
     let!(:notice_1) { Fabricate(:notice, :err => merged_errs.first) }
+
     it 'delete one of problem' do
       expect {
         problem_merge.merge
@@ -44,5 +45,18 @@
       ProblemUpdaterCache.should_receive(:new).with(problem).and_return(mock(:update => true))
       problem_merge.merge
     end
+
+    context "with problem with comment" do
+      let!(:comment) { Fabricate(:comment, :err => problem ) }
+      let!(:comment_2) { Fabricate(:comment, :err => problem_1, :user => comment.user ) }
+      it 'merge comment' do
+        expect {
+          problem_merge.merge
+        }.to change{
+          problem.comments.size
+        }.from(1).to(2)
+        expect(comment_2.reload.err).to eq problem
+      end
+    end
   end
 end