Merged VatRateDetermination into InvoiceGeneration process

It's the first step of simplifying (hopefully) the invoice generation ceremony and keeping it in one place.
Next step is to merge ItemInvoicingProcess here too.

Author: andrzejkrzywda

rails_application/app/processes/processes/configuration.rb

@@ -10,7 +10,6 @@ def call(event_store, command_bus)
       enable_coupon_discount_process(event_store, command_bus)
       notify_payments_about_order_total_value(event_store, command_bus)
       enable_shipment_sync(event_store, command_bus)
-      determine_vat_rates_on_order_placed(event_store, command_bus)
       set_invoice_payment_date_when_order_confirmed(event_store, command_bus)
       enable_product_name_sync(event_store, command_bus)
       confirm_order_on_payment_captured(event_store, command_bus)
@@ -71,15 +70,6 @@ def enable_order_item_invoicing_process(event_store, command_bus)
       )
     end
 
-    def determine_vat_rates_on_order_placed(event_store, command_bus)
-      event_store.subscribe(
-        DetermineVatRatesOnOrderPlaced.new(event_store, command_bus),
-        to: [
-          Pricing::OfferAccepted,
-          Fulfillment::OrderRegistered
-        ]
-      )
-    end
 
     def enable_product_name_sync(event_store, command_bus)
       Infra::Process.new(event_store, command_bus)

rails_application/app/processes/processes/determine_vat_rates_on_order_placed.rb

@@ -7,11 +7,13 @@ class InvoiceGeneration
       Pricing::PriceItemRemoved,
       Pricing::PercentageDiscountSet,
       Pricing::PercentageDiscountChanged,
-      Pricing::PercentageDiscountRemoved
+      Pricing::PercentageDiscountRemoved,
+      Fulfillment::OrderRegistered
     )
 
     def act
       calculate_sub_amounts
+      determine_vat_rates if state.placed?
     end
 
     private
@@ -33,6 +35,8 @@ def apply(event)
         apply_percentage_discount_changed(event)
       when Pricing::PercentageDiscountRemoved
         apply_percentage_discount_removed(event)
+      when Fulfillment::OrderRegistered
+        apply_order_registered
       else
         state
       end
@@ -121,11 +125,22 @@ def apply_discounts_to_existing_lines(new_state)
       new_state.with(lines: updated_lines)
     end
 
+    def determine_vat_rates
+      state.sub_amounts_total.each_key do |product_id|
+        command = Taxes::DetermineVatRate.new(order_id: @order_id, product_id: product_id)
+        command_bus.call(command)
+      end
+    end
+
+    def apply_order_registered
+      state.with(order_placed: true)
+    end
+
   end
 
-  Invoice = Data.define(:lines, :discounts) do
-    def initialize(lines: [], discounts: [])
-      super(lines: lines.freeze, discounts: discounts.freeze)
+  Invoice = Data.define(:lines, :discounts, :order_placed) do
+    def initialize(lines: [], discounts: [], order_placed: false)
+      super(lines: lines.freeze, discounts: discounts.freeze, order_placed: order_placed)
     end
 
     def sub_amounts_total
@@ -153,6 +168,10 @@ def final_discount_percentage
     def discounted_value
       subtotal * (1 - final_discount_percentage / 100.0)
     end
+
+    def placed?
+      order_placed
+    end
   end
 
 end

rails_application/app/processes/processes/invoice_generation.rb

@@ -2,39 +2,39 @@
 
 module Processes
   class DetermineVatRateTest < ProcessTest
-    cover "Processes::DetermineVatRatesOnOrderPlaced*"
+    cover "Processes::InvoiceGeneration*"
 
     def test_happy_path
       product_id = SecureRandom.uuid
-      process = DetermineVatRatesOnOrderPlaced.new(event_store, command_bus)
-      given([offer_accepted(order_id, product_id), order_placed]).each do |event|
+      process = InvoiceGeneration.new(event_store, command_bus)
+      given([price_item_added(order_id, product_id), order_placed]).each do |event|
         process.call(event)
       end
       assert_command(Taxes::DetermineVatRate.new(order_id: order_id, product_id: product_id))
     end
 
-    def test_accepted_but_not_placed
-      process = DetermineVatRatesOnOrderPlaced.new(event_store, command_bus)
-      given([offer_accepted(order_id, SecureRandom.uuid)]).each do |event|
+    def test_price_added_but_not_placed
+      process = InvoiceGeneration.new(event_store, command_bus)
+      given([price_item_added(order_id, SecureRandom.uuid)]).each do |event|
         process.call(event)
       end
       assert_no_command
     end
 
     def test_placed_but_not_accepted
-      process = DetermineVatRatesOnOrderPlaced.new(event_store, command_bus)
+      process = InvoiceGeneration.new(event_store, command_bus)
       given([order_placed]).each do |event|
         process.call(event)
       end
       assert_no_command
     end
 
     def test_stream_name
-      process = DetermineVatRatesOnOrderPlaced.new(event_store, command_bus)
+      process = InvoiceGeneration.new(event_store, command_bus)
       given([order_placed]).each do |event|
         process.call(event)
       end
-      assert_equal "Processes::DetermineVatRatesOnOrderPlaced$#{order_id}", process.send(:stream_name)
+      assert_equal "Processes::InvoiceGeneration$#{order_id}", process.send(:stream_name)
     end
 
     private
@@ -43,11 +43,13 @@ def command_bus
       @command_bus
     end
 
-    def offer_accepted(order_id, product_id)
-      Pricing::OfferAccepted.new(
+    def price_item_added(order_id, product_id)
+      Pricing::PriceItemAdded.new(
         data: {
           order_id: order_id,
-          order_lines: [{ product_id: product_id, quantity: 1 }]
+          product_id: product_id,
+          base_price: 100,
+          price: 100
         }
       )
     end