Allow to recalculate cart prices

core/app/models/spree/line_item.rb

@@ -127,6 +127,15 @@ def options=(options = {})
       end
     end
 
+    # Recalculate the price using the pricing options for this line item.
+    # Useful for making sure carts are up-to-date when prices change.
+    # Will not make changes to completed orders.
+    #
+    def recalculate_price
+      return if order.completed?
+      self.money_price = variant.price_for_options(pricing_options)&.money
+    end
+
     def pricing_options
       Spree::Config.pricing_options_class.from_line_item(self)
     end

core/app/models/spree/order_updater.rb

@@ -18,6 +18,7 @@ def initialize(order)
     # associations try to save and then in turn try to call +update!+ again.)
     def recalculate
       order.transaction do
+        recalculate_line_item_prices
         recalculate_item_count
         update_shipment_amounts
         update_totals
@@ -240,5 +241,11 @@ def recalculate_item_totals
         )
       end
     end
+
+    def recalculate_line_item_prices
+      if Spree::Config.recalculate_cart_prices
+        line_items.each(&:recalculate_price)
+      end
+    end
   end
 end

core/lib/generators/solidus/install/templates/config/initializers/spree.rb.tt

@@ -21,6 +21,9 @@ Spree.config do |config|
   config.image_attachment_module = 'Spree::Image::ActiveStorageAttachment'
   config.taxon_attachment_module = 'Spree::Taxon::ActiveStorageAttachment'
 
+  # Uncomment to recalculate cart prices when the cart changes
+  # config.recalculate_cart_prices = true
+
   # Defaults
   # Permission Sets:
 

core/lib/spree/app_configuration.rb

@@ -245,6 +245,10 @@ class AppConfiguration < Preferences::Configuration
     #   @return [Integer] Products to show per-page in the frontend (default: +12+)
     preference :products_per_page, :integer, default: 12
 
+    # @!attribute [rw] recalculate_cart_prices
+    #   @return [Boolean] Whether to recalculate cart prices when recalculating (default: +false+)
+    versioned_preference :recalculate_cart_prices, :boolean, initial_value: false, boundaries: { "5.0.0.alpha" => true }
+
     # @!attribute [rw] require_master_price
     #   @return [Boolean] Require a price on the master variant of a product (default: +true+)
     preference :require_master_price, :boolean, default: true

core/spec/lib/spree/app_configuration_spec.rb

@@ -248,4 +248,18 @@ class DummyClass; end;
       expect(prefs[:meta_data_max_value_length]).to eq(256)
     end
   end
+
+  describe "#recalculate_cart_prices" do
+    subject { prefs[:recalculate_cart_prices] }
+
+    it { is_expected.to be false }
+
+    context "if solidus version is 5.0" do
+      before do
+        prefs.load_defaults "5.0"
+      end
+
+      it { is_expected.to be true }
+    end
+  end
 end

core/spec/models/spree/line_item_spec.rb

@@ -184,5 +184,25 @@
     end
   end
 
+  describe "#recalculate_price" do
+    let(:order) { create(:order) }
+    let(:variant) { create(:variant, price: 14.99) }
+    let(:line_item) { build(:line_item, order:, variant:, price: 13.39) }
+
+    subject { line_item.recalculate_price }
+
+    it "updates the price of the line item" do
+      expect { subject }.to change { line_item.price }.from(13.39).to(14.99)
+    end
+
+    context "if order is completed" do
+      let(:order) { create(:order, completed_at: 1.hour.ago) }
+
+      it "does not update line item prices" do
+        expect { subject }.not_to change { line_item.price }.from(13.39)
+      end
+    end
+  end
+
   it_behaves_like "customer and admin metadata fields: storage and validation", :line_item
 end

core/spec/models/spree/order_updater_spec.rb

@@ -267,6 +267,39 @@ module Spree
       end
     end
 
+    describe "price recalculation" do
+      let(:variant) { create(:variant, price: 98) }
+      let!(:order) { create(:order_with_line_items, line_items_attributes: [{ variant:, price: 98 }]) }
+
+      subject { updater.recalculate }
+
+      before do
+        variant.price = 100
+        variant.save!
+        order.reload
+      end
+
+      context "when recalculate_cart_prices is true" do
+        before do
+          stub_spree_preferences(recalculate_cart_prices: true)
+        end
+
+        it "sets prices to the currently active price" do
+          expect { subject }.to change { order.line_items.first.price }.from(98).to(100)
+        end
+      end
+
+      context "when recalculate_cart_prices is false" do
+        before do
+          stub_spree_preferences(recalculate_cart_prices: false)
+        end
+
+        it "does not recalculate prices" do
+          expect { subject }.not_to change { order.line_items.first.price }.from(98)
+        end
+      end
+    end
+
     context "updating shipment state" do
       let(:order) { create :order_with_line_items }