Fixed issue #1216 - Race condition if agents merge ticket at same tim…

…e but in different directions.

app/models/ticket.rb

@@ -275,6 +275,11 @@ def self.process_escalation
 
   def merge_to(data)
 
+    # prevent cross merging tickets
+    target_ticket = Ticket.find(data[:ticket_id])
+    raise 'no target ticket given' if !target_ticket
+    raise 'invalid state for target ticket' if target_ticket.state.name == 'merged'
+
     # update articles
     Transaction.execute do
 
@@ -317,7 +322,7 @@ def merge_to(data)
       save!
 
       # touch new ticket (to broadcast change)
-      Ticket.find(data[:ticket_id]).touch
+      target_ticket.touch
     end
     true
   end

spec/factories/ticket.rb

@@ -0,0 +1,11 @@
+FactoryGirl.define do
+  factory :ticket do
+    title 'Test Ticket'
+    group { Group.lookup(name: 'Users') }
+    customer { FactoryGirl.create(:customer_user) }
+    state { Ticket::State.lookup(name: 'new') }
+    priority { Ticket::Priority.lookup(name: '2 normal') }
+    updated_by_id 1
+    created_by_id 1
+  end
+end

spec/factories/user.rb

@@ -18,6 +18,10 @@
     created_by_id 1
   end
 
+  factory :customer_user, parent: :user do
+    role_ids { Role.signup_role_ids.sort }
+  end
+
   factory :user_login_failed, parent: :user do
     login_failed { (Setting.get('password_max_login_failed').to_i || 10) + 1 }
   end

spec/models/ticket_spec.rb

@@ -0,0 +1,27 @@
+require 'rails_helper'
+
+RSpec.describe Ticket do
+
+  describe '.merge_to' do
+
+    it 'prevents cross merging tickets' do
+      source_ticket     = create(:ticket)
+      target_ticket     = create(:ticket)
+
+      result = source_ticket.merge_to(
+        ticket_id: target_ticket.id,
+        user_id:   1,
+      )
+      expect(result).to be(true)
+
+      expect {
+        result = target_ticket.merge_to(
+          ticket_id: source_ticket.id,
+          user_id:   1,
+        )
+      }.to raise_error('invalid state for target ticket')
+    end
+
+  end
+
+end