Support conditional persist in promotion chooser

Previously this would update the eligible column. We now only assign the
value and then save if persist is true.

Co-Authored-By: Adam Mueller <adam@super.gd>
Co-Authored-By: Andrew Stewart <andrew@super.gd>
Co-Authored-By: Harmony Evangelina <harmony@super.gd>
Co-Authored-By: Jared Norman <jared@super.gd>
Co-Authored-By: Kendra Riga <kendra@super.gd>
Co-Authored-By: benjamin wil <benjamin@super.gd>
Co-Authored-By: Chris Todorov <chris@super.gd>
Co-Authored-By: Nick Van Doorn <nick@super.gd>
Co-Authored-By: Sofia Besenski <sofia@super.gd>

Author: 10 people

legacy_promotions/app/models/spree/promotion/order_adjustments_recalculator.rb

@@ -36,6 +36,8 @@ def call(persist: true)
                               select(&:eligible?).
                               select(&:promotion?).
                               sum(&:amount)
+
+        order.save! if persist
         order
       end
 

legacy_promotions/app/models/spree/promotion_chooser.rb

@@ -14,7 +14,7 @@ def update
       if best_promotion_adjustment
         @adjustments.select(&:eligible?).each do |adjustment|
           next if adjustment == best_promotion_adjustment
-          adjustment.update_columns(eligible: false, updated_at: Time.current)
+          adjustment.eligible = false
         end
         best_promotion_adjustment.amount
       else

legacy_promotions/spec/models/spree/promotion/order_adjustments_recalculator_spec.rb

@@ -1,9 +1,12 @@
 # frozen_string_literal: true
 
 require 'rails_helper'
+require 'db-query-matchers'
 
 RSpec.describe Spree::Promotion::OrderAdjustmentsRecalculator do
-  subject { described_class.new(order).call }
+  subject { described_class.new(order).call(persist:) }
+
+  let(:persist) { true }
 
   describe '#call ' do
     describe 'promotion recalculation' do
@@ -44,6 +47,27 @@
             order.promo_total
           }.from(-1).to(-2)
         end
+
+        context "when persist is false" do
+          let(:persist) { false }
+
+          it "does not persist changes to order" do
+            order.promotions << create(:promotion, :with_line_item_adjustment, adjustment_rate: 2)
+            Spree::PromotionHandler::Cart.new(order).activate
+
+            expect(order.promo_total).to eq -1
+
+            expect {
+              subject
+            }.not_to make_database_queries(manipulative: true)
+
+            expect(order.promo_total).to eq -2
+
+            expect { order.reload }
+              .to change { order.promo_total }
+              .from(-2).to(-1)
+          end
+        end
       end
 
       context 'promotion chooser customization' do