Merge branch 'fix_each_batch_scope_leaking' into 'master'

Fix the leaking scope of `each_batch`

See merge request gitlab-org/gitlab!67459

app/models/concerns/each_batch.rb

@@ -91,7 +91,11 @@ module EachBatch
 
         # Any ORDER BYs are useless for this relation and can lead to less
         # efficient UPDATE queries, hence we get rid of it.
-        yield relation.except(:order), index
+        relation = relation.except(:order)
+
+        # Using unscoped is necessary to prevent leaking the current scope used by
+        # ActiveRecord to chain `each_batch` method.
+        unscoped { yield relation, index }
 
         break unless stop
       end

spec/models/concerns/each_batch_spec.rb

@@ -9,6 +9,8 @@ RSpec.describe EachBatch do
         include EachBatch
 
         self.table_name = 'users'
+
+        scope :never_signed_in, -> { where(sign_in_count: 0) }
       end
     end
 
@@ -72,5 +74,16 @@ RSpec.describe EachBatch do
 
       expect(ids).to eq(ids.sort.reverse)
     end
+
+    describe 'current scope' do
+      let(:entry) { create(:user, sign_in_count: 1) }
+      let(:ids_with_new_relation) { model.where(id: entry.id).pluck(:id) }
+
+      it 'does not leak current scope to block being executed' do
+        model.never_signed_in.each_batch(of: 5) do |relation|
+          expect(ids_with_new_relation).to include(entry.id)
+        end
+      end
+    end
   end
 end