get three plus one free process work without pricing catalog

ecommerce/pricing/lib/pricing/events.rb

@@ -47,6 +47,7 @@ class PriceItemAdded < Infra::Event
   class PriceItemRemoved < Infra::Event
     attribute :order_id, Infra::Types::UUID
     attribute :product_id, Infra::Types::UUID
+    attribute :price, Infra::Types::Price
   end
 
   class PercentageDiscountRemoved < Infra::Event

ecommerce/pricing/lib/pricing/offer.rb

@@ -23,10 +23,12 @@ def add_item(product_id, price)
     end
 
     def remove_item(product_id)
+      price = @list.lowest_price(product_id)
       apply PriceItemRemoved.new(
         data: {
           order_id: @id,
-          product_id: product_id
+          product_id: product_id,
+          price: price
         }
       )
     end
@@ -158,7 +160,7 @@ def expire
     end
 
     on PriceItemRemoved do |event|
-      @list.remove_item(event.data.fetch(:product_id))
+      @list.remove_item(event.data.fetch(:product_id), event.data.fetch(:price))
     end
 
     on PriceItemValueCalculated do |event|
@@ -220,11 +222,9 @@ def add_item(product_id, price)
         @items << Item.new(product_id:, price:, quantity: 1)
       end
 
-      def remove_item(product_id)
-        new_items = @items.sort { _1.price}
-        index_of_item_to_remove = new_items.index { |item| item.product_id == product_id }
-        new_items.delete_at(index_of_item_to_remove)
-        @items = new_items
+      def remove_item(product_id, price)
+        index_of_item_to_remove = @items.index { |item| item.product_id == product_id && item.price == price }
+        @items.delete_at(index_of_item_to_remove)
       end
 
       def contains_free_products?
@@ -251,10 +251,19 @@ def set_free(product_id)
 
       def restore_nonfree(product_id)
         idx = @items.index { |item| item.product_id == product_id && item.price == 0 }
+        return unless idx
         old_item = @items.delete_at(idx)
         @items << old_item.with(price: old_item.catalog_price)
       end
 
+      def lowest_price(product_id)
+        @items
+          .select { |item| item.product_id == product_id }
+          .sort_by(&:price)
+          .first
+          &.price
+      end
+
       def quantities
         sub_amounts_total.map do |product_id, h|
           { product_id:, quantity: h.fetch(:quantity) }

ecommerce/processes/lib/processes/three_plus_one_free.rb

@@ -39,8 +39,7 @@ def build_state(event)
     end
 
     def make_or_remove_free_product(state)
-      pricing_catalog = Pricing::PricingCatalog.new(@event_store)
-      free_product_id = FreeProductResolver.new(state, pricing_catalog).call
+      free_product_id = state.cheapest_product
 
       return if current_free_product_not_changed?(free_product_id, state)
 
@@ -69,51 +68,28 @@ class ProcessState
 
       def initialize(order_id)
         @order_id = order_id
-        @order_lines = Hash.new(0)
+        @order_lines = []
       end
 
       def call(event)
         product_id = event.data.fetch(:product_id)
         case event
         when Pricing::PriceItemAdded
-          order_lines[product_id] += 1
+          order_lines << { product_id: event.data.fetch(:product_id), price: event.data.fetch(:price) }
         when Pricing::PriceItemRemoved
-          order_lines[product_id] -= 1
-          order_lines.delete(product_id) if order_lines.fetch(product_id) <= 0
+          index_of_line_to_remove = order_lines.index { |line| line.fetch(:product_id) == product_id && line.fetch(:price) == event.data.fetch(:price) }
+          @order_lines.delete_at(index_of_line_to_remove)
+          @current_free_product_id = nil if event.data.fetch(:price) == 0
         when Pricing::ProductMadeFreeForOrder
           @current_free_product_id = product_id
         when Pricing::FreeProductRemovedFromOrder
           @current_free_product_id = nil
         end
       end
 
-      def total_quantity
-        order_lines.values.sum
-      end
-    end
-
-    class FreeProductResolver
       MIN_ORDER_LINES_QUANTITY = 4
-
-      def initialize(state, pricing_catalog)
-        @state = state
-        @pricing_catalog = pricing_catalog
-      end
-
-      def call
-        cheapest_product if eligible_for_free_product?
-      end
-
-      private
-
-      attr_reader :state, :pricing_catalog
-
       def cheapest_product
-        state.order_lines.keys.sort_by { |product_id| pricing_catalog.price_by_product_id(product_id) }.first
-      end
-
-      def eligible_for_free_product?
-        state.total_quantity >= MIN_ORDER_LINES_QUANTITY
+        order_lines.sort_by { |line| line.fetch(:price) }.first.fetch(:product_id) if order_lines.size >= MIN_ORDER_LINES_QUANTITY
       end
     end
   end

ecommerce/processes/test/test_helper.rb

@@ -59,7 +59,7 @@ def customer_id
     end
 
     def given(events, store: event_store, process: nil)
-      events.each do |ev|
+      events.flatten.each do |ev|
         store.append(ev)
         process.call(ev) if process
       end

ecommerce/processes/test/three_plus_one_free_test.rb

@@ -4,17 +4,11 @@ module Processes
   class ThreePlusOneFreeTest < Test
     cover "Processes::ThreePlusOneFree*"
 
-    def setup
-      skip "ThreePlusOneFree process block us from removing Pricing::PricingCatalog"
-    end
-
     def test_one_order_line_is_not_eligible_for_free_product
       product_id = SecureRandom.uuid
       order_id = SecureRandom.uuid
       process = ThreePlusOneFree.new(event_store, command_bus)
-      given(item_added_event(order_id, product_id, 22)).each do |event|
-        process.call(event)
-      end
+      given(item_added_event(order_id, product_id, 22), process:)
       assert_no_command
     end
 
@@ -23,9 +17,7 @@ def test_four_order_lines_are_eligible_for_free_product
       order_id = SecureRandom.uuid
       process = ThreePlusOneFree.new(event_store, command_bus)
       given([set_price(product_id, 20)])
-      given(item_added_event(order_id, product_id, 20, times: 4)).each do |event|
-        process.call(event)
-      end
+      given(item_added_event(order_id, product_id, 20, times: 4), process:)
       assert_command(Pricing::MakeProductFreeForOrder.new(order_id: order_id, product_id: product_id))
     end
 
@@ -34,12 +26,11 @@ def test_remove_free_product_when_order_lines_qtn_is_less_than_four
       order_id = SecureRandom.uuid
       process = ThreePlusOneFree.new(event_store, command_bus)
       given([set_price(product_id, 20)])
-      given(item_added_event(order_id, product_id, 20, times:4) +
-              product_made_for_free(order_id, product_id) +
-              item_removed_event(order_id, product_id, times: 1) +
-              free_product_removed(order_id, product_id)).each do |event|
-        process.call(event)
-      end
+      given([item_added_event(order_id, product_id, 20, times: 4),
+             product_made_for_free(order_id, product_id),
+             item_removed_event(order_id, product_id, 20, times: 1),
+             free_product_removed(order_id, product_id)
+            ], process:)
 
       assert_all_commands(Pricing::MakeProductFreeForOrder.new(order_id: order_id, product_id: product_id),
                           Pricing::RemoveFreeProductFromOrder.new(order_id: order_id, product_id: product_id))
@@ -53,14 +44,12 @@ def test_change_free_product_if_new_order_line_is_the_cheapest
       given([set_price(product_id, 20)])
       given([set_price(cheapest_product_id, 1)])
 
-      given(item_added_event(order_id, product_id, 20, times:4) +
-               product_made_for_free(order_id, product_id) +
-               item_added_event(order_id, cheapest_product_id, 1) +
-               free_product_removed(order_id, product_id) +
-               product_made_for_free(order_id, cheapest_product_id)
-      ).each do |event|
-        process.call(event)
-      end
+      given([item_added_event(order_id, product_id, 20, times: 4),
+             product_made_for_free(order_id, product_id),
+             item_added_event(order_id, cheapest_product_id, 1),
+             free_product_removed(order_id, product_id),
+             product_made_for_free(order_id, cheapest_product_id)
+            ], process:)
 
       assert_all_commands(Pricing::MakeProductFreeForOrder.new(order_id: order_id, product_id: product_id),
                           Pricing::RemoveFreeProductFromOrder.new(order_id: order_id, product_id: product_id),
@@ -75,11 +64,10 @@ def test_do_not_change_free_product_if_new_order_line_is_more_expensive
       given([set_price(product_id, 20)])
       given([set_price(more_expensive_product_id, 50)])
 
-      given(item_added_event(order_id, product_id, 20, times: 4) +
-              product_made_for_free(order_id, product_id) +
-              item_added_event(order_id, more_expensive_product_id, 50)).each do |event|
-        process.call(event)
-      end
+      given([item_added_event(order_id, product_id, 20, times: 4),
+             product_made_for_free(order_id, product_id),
+             item_added_event(order_id, more_expensive_product_id, 50)
+            ], process:)
 
       assert_all_commands(Pricing::MakeProductFreeForOrder.new(order_id: order_id, product_id: product_id))
     end
@@ -92,16 +80,15 @@ def test_change_free_product_if_the_cheapest_order_line_is_removed
       given([set_price(product_id, 20)])
       given([set_price(cheapest_product_id, 1)])
 
-      given(item_added_event(order_id, product_id, 20, times: 4) +
-              product_made_for_free(order_id, product_id) +
-              item_added_event(order_id, cheapest_product_id, 1) +
-              free_product_removed(order_id, product_id) +
-              product_made_for_free(order_id, cheapest_product_id) +
-              item_removed_event(order_id, cheapest_product_id) +
-              free_product_removed(order_id, cheapest_product_id) +
-              product_made_for_free(order_id, product_id)).each do |event|
-        process.call(event)
-      end
+      given([item_added_event(order_id, product_id, 20, times: 4),
+             product_made_for_free(order_id, product_id),
+             item_added_event(order_id, cheapest_product_id, 1),
+             free_product_removed(order_id, product_id),
+             product_made_for_free(order_id, cheapest_product_id),
+             item_removed_event(order_id, cheapest_product_id, 1),
+             free_product_removed(order_id, cheapest_product_id),
+             product_made_for_free(order_id, product_id),
+            ], process:)
 
       assert_all_commands(Pricing::MakeProductFreeForOrder.new(order_id: order_id, product_id: product_id),
                           Pricing::RemoveFreeProductFromOrder.new(order_id: order_id, product_id: product_id),
@@ -114,50 +101,37 @@ def test_change_free_product_if_the_cheapest_order_line_is_removed
     private
 
     def set_price(product_id, amount)
-      Pricing::PriceSet.new(data: { product_id: product_id, price: amount })
+      Pricing::PriceSet.new(data: { product_id:, price: amount })
     end
 
     def item_added_event(order_id, product_id, price, times: 1)
       times.times.collect do
         Pricing::PriceItemAdded.new(
-          data: {
-            order_id: order_id,
-            product_id: product_id,
-            price: price
-          }
+          data: { order_id:, product_id:, price: }
         )
       end
     end
 
-    def item_removed_event(order_id, product_id, times: 1)
+    def item_removed_event(order_id, product_id, price, times: 1)
       times.times.collect do
         Pricing::PriceItemRemoved.new(
-          data: {
-            order_id: order_id,
-            product_id: product_id
-          }
+          data: { order_id:, product_id:, price: }
         )
       end
     end
 
     def product_made_for_free(order_id, product_id)
       [
         Pricing::ProductMadeFreeForOrder.new(
-          data: {
-            order_id: order_id,
-            product_id: product_id
-          }
+          data: { order_id:, product_id: }
         )
       ]
     end
 
     def free_product_removed(order_id, product_id)
       [
         Pricing::FreeProductRemovedFromOrder.new(
-          data: {
-            order_id: order_id,
-            product_id: product_id
-          }
+          data: { order_id:, product_id: }
         )
       ]
     end

infra/lib/infra/types.rb

@@ -13,7 +13,7 @@ module Types
     OrderNumber =
       Types::Strict::String.constrained(format: /\A\d{4}\/\d{2}\/\d+\z/i)
     Quantity = Types::Strict::Integer.constrained(gt: 0)
-    Price = Types::Coercible::Decimal.constrained(gt: 0)
+    Price = Types::Coercible::Decimal.constrained(gteq: 0)
     Value = Types::Coercible::Decimal
     PercentageDiscount = Types::Coercible::Decimal.constrained(gt: 0, lteq: 100)
     CouponDiscount = Types::Coercible::Decimal.constrained(gt: 0, lteq: 100)

rails_application/test/client_orders/item_removed_from_basket_test.rb

@@ -47,7 +47,8 @@ def test_remove_item_when_quantity_gt_1
         Pricing::PriceItemRemoved.new(
           data: {
             order_id: order_id,
-            product_id: product_id
+            product_id: product_id,
+            price: 20,
           }
         )
       )
@@ -93,7 +94,8 @@ def test_remove_item_when_quantity_eq_1
         Pricing::PriceItemRemoved.new(
           data: {
             order_id: order_id,
-            product_id: product_id
+            product_id: product_id,
+            price: 20,
           }
         )
       )
@@ -169,7 +171,8 @@ def test_remove_item_when_there_is_another_item
         Pricing::PriceItemRemoved.new(
           data: {
             order_id: order_id,
-            product_id: another_product_id
+            product_id: another_product_id,
+            price: 20,
           }
         )
       )

rails_application/test/orders/broadcast_test.rb

@@ -95,6 +95,7 @@ def test_broadcast_remove_item_from_basket
           data: {
             order_id: order_id,
             product_id: product_id,
+            price: 20,
           }
         )
       )

rails_application/test/orders/item_removed_from_basket_test.rb

@@ -46,7 +46,8 @@ def test_remove_item_when_quantity_gt_1
       item_removed_from_basket = Pricing::PriceItemRemoved.new(
         data: {
           order_id: order_id,
-          product_id: product_id
+          product_id: product_id,
+          price: 20,
         }
       )
       event_store.publish(item_removed_from_basket)
@@ -93,7 +94,8 @@ def test_remove_item_when_quantity_eq_1
         Pricing::PriceItemRemoved.new(
           data: {
             order_id: order_id,
-            product_id: product_id
+            product_id: product_id,
+            price: 20,
           }
         )
       )
@@ -169,7 +171,8 @@ def test_remove_item_when_there_is_another_item
         Pricing::PriceItemRemoved.new(
           data: {
             order_id: order_id,
-            product_id: another_product_id
+            product_id: another_product_id,
+            price: 20,
           }
         )
       )