Introduce new InMemoryOrderAdjuster class for promotions

This is just a stub for now, but we want to eventually introduce a class
to handle running the promotion adjustments in memory.

Co-authored-by: Adam Mueller <[email protected]>
Co-authored-by: Andrew Stewart <[email protected]>
Co-authored-by: Harmony Evangelina <[email protected]>
Co-authored-by: Kendra Riga <[email protected]>
Co-authored-by: Jared Norman <[email protected]>
Co-authored-by: Tom Van Manen <[email protected]>
Co-authored-by: Senem Soy <[email protected]>
Co-authored-by: Benjamin Willems <[email protected]>

core/app/models/spree/in_memory_order_updater.rb

@@ -121,7 +121,7 @@ def recalculate_adjustments(persist:)
       # http://www.hmrc.gov.uk/vat/managing/charging/discounts-etc.htm#1
       # It also fits the criteria for sales tax as outlined here:
       # http://www.boe.ca.gov/formspubs/pub113/
-      update_promotions
+      update_promotions(persist:)
       update_taxes
       update_item_totals(persist:)
     end
@@ -203,8 +203,12 @@ def log_state_change(name)
       end
     end
 
-    def update_promotions
-      Spree::Config.promotions.order_adjuster_class.new(order).call
+    def update_promotions(persist:)
+      if persist
+        Spree::Config.promotions.order_adjuster_class
+      else
+        InMemoryOrderAdjuster
+      end.new(order).call
     end
 
     def update_taxes
@@ -247,5 +251,13 @@ def update_item_totals(persist:)
         end
       end
     end
+
+    class InMemoryOrderAdjuster
+      def initialize(order)
+      end
+
+      def call
+      end
+    end
   end
 end

core/spec/models/spree/in_memory_order_updater_spec.rb

@@ -136,6 +136,17 @@ module Spree
           expect(adjuster).to receive(:call)
           order.recalculate
         end
+
+        context "when recalculating the order in memory" do
+          it "raises an error" do
+            order_adjuster = double
+            allow(order_adjuster).to receive(:call) { raise NotImplementedError }
+            allow(Spree::InMemoryOrderUpdater::InMemoryOrderAdjuster).to receive(:new).and_return(order_adjuster)
+
+            expect{described_class.new(order).recalculate(persist: false)}
+              .to raise_error(NotImplementedError)
+          end
+        end
       end
 
       describe 'tax recalculation' do