Using a more efficient way to check for group/user equality

ee/app/models/approval_merge_request_rule.rb

@@ -140,11 +140,17 @@ class ApprovalMergeRequestRule < ApplicationRecord
   private
 
   def different_groups?
-    groups.sort != approval_project_rule.groups.sort
+    group_ids = groups.collect(&:id)
+    apr_group_ids = approval_project_rule.groups.pluck(:id)
+
+    group_ids & apr_group_ids == group_ids
   end
 
   def different_users?
-    users.sort != approval_project_rule.users.sort
+    user_ids = users.collect(&:id)
+    apr_user_ids = approval_project_rule.users.pluck(:id)
+
+    user_ids & apr_user_ids == user_ids
   end
 
   def different_name_or_approvals_required?

ee/spec/models/approval_merge_request_rule_spec.rb

@@ -36,6 +36,32 @@ RSpec.describe ApprovalMergeRequestRule do
         it 'is valid' do
           expect(merge_request_rule).to be_valid
         end
+
+        context 'the MR rule shows that its modified from the original' do
+          it 'by having different groups' do
+            first_group = create(:group)
+            second_group = create(:group)
+            third_group = create(:group)
+
+            approval_project_rule.groups = [first_group, second_group]
+            approval_project_rule.save!
+            merge_request_rule.groups = [first_group, third_group]
+
+            expect(merge_request_rule.different_from_project_rule?).to be true
+          end
+
+          it 'by having different users' do
+            first_user = create(:user)
+            second_user = create(:user)
+            third_user = create(:user)
+
+            approval_project_rule.users = [first_user, second_user]
+            approval_project_rule.save!
+            merge_request_rule.users = [first_user, third_user]
+
+            expect(merge_request_rule.different_from_project_rule?).to be true
+          end
+        end
       end
 
       context 'when the project of approval_project_rule and merge request does not match' do

spec/lib/gitlab/background_migration/add_modified_to_approval_merge_request_rule_spec.rb

@@ -33,16 +33,16 @@ RSpec.describe Gitlab::BackgroundMigration::AddModifiedToApprovalMergeRequestRul
     sources.create!(approval_project_rule_id: overridden_project_rule.id, approval_merge_request_rule_id: overridden_merge_rule.id)
     sources.create!(approval_project_rule_id: overridden_project_rule_two.id, approval_merge_request_rule_id: overridden_merge_rule_two.id)
 
-    group1 = groups.create!(name: "1", path: "test_group1", type: 'Group')
-    group2 = groups.create!(name: "2", path: "test_group2", type: 'Group')
-    group3 = groups.create!(name: "3", path: "test_group3", type: 'Group')
+    group1 = groups.create!(name: "group1", path: "test_group1", type: 'Group')
+    group2 = groups.create!(name: "group2", path: "test_group2", type: 'Group')
+    group3 = groups.create!(name: "group3", path: "test_group3", type: 'Group')
 
     project_groups.create!(approval_project_rule_id: overridden_project_rule_two.id, group_id: group1.id)
     project_groups.create!(approval_project_rule_id: overridden_project_rule_two.id, group_id: group2.id)
     project_groups.create!(approval_project_rule_id: overridden_project_rule_two.id, group_id: group3.id)
 
-    mr_groups.create!(approval_merge_request_rule_id: overridden_project_rule_two.id, group_id: group1.id)
-    mr_groups.create!(approval_merge_request_rule_id: overridden_project_rule_two.id, group_id: group2.id)
+    mr_groups.create!(approval_merge_request_rule_id: overridden_merge_rule.id, group_id: group1.id)
+    mr_groups.create!(approval_merge_request_rule_id: overridden_merge_rule_two.id, group_id: group2.id)
   end
 
   describe '#perform' do