only clear updated dirty attributes

Author: freddiescadding-pennylane

lib/activerecord_batch_update.rb

@@ -35,7 +35,7 @@ def batch_update(entries, columns:, batch_size: 100, validate: true)
       end
 
       connection.clear_query_cache if connection.query_cache_enabled
-      entries.each(&:changes_applied)
+      entries.each { _1.clear_attribute_changes(columns) }
 
       updated_count
     end

spec/activerecord_batch_update_spec.rb

@@ -180,11 +180,29 @@
                                                                          .and(change { cat2.reload.birthday })
       end
 
-      it 'clears the changes after the update' do
-        cat1.name = 'Nala'
-        Cat.batch_update([cat1], columns: :all)
+      context 'when saving all dirty attributes' do
+        it 'clears all changes after the update' do
+          cat1.name = 'Nala'
+          Cat.batch_update([cat1], columns: :all)
 
-        expect(cat1.changes_to_save).to be_empty
+          expect(cat1.changes_to_save).to be_empty
+        end
+      end
+
+      context 'when saving only some of the dirty attributes' do
+        it 'clears changes made during the update' do
+          cat1.assign_attributes(
+            name: 'Nala',
+            birthday: Date.new(2015, 1, 1)
+          )
+          Cat.batch_update([cat1], columns: :name)
+
+          expect(cat1.changes_to_save).to eq(
+            {
+              'birthday' => [Date.new(2010, 1, 1), Date.new(2015, 1, 1)]
+            }
+          )
+        end
       end
 
       context 'when some fields are encrypted' do