OfferDrafted is the new event that starts the lifecycle of an offer

So far we didn't have such event, adding items was the first event.
Explicit event feels right to have.
It will allow easier multitenancy, as we now can register such offer within StoresBC.

Author: andrzejkrzywda

ecommerce/pricing/lib/pricing.rb

@@ -15,6 +15,10 @@ module Pricing
   class Configuration
     def call(event_store, command_bus)
 
+      command_bus.register(
+        DraftOffer,
+        DraftOfferHandler.new(event_store)
+      )
       command_bus.register(
         AddPriceItem,
         OnAddItemToBasket.new(event_store)

ecommerce/pricing/lib/pricing/commands.rb

@@ -1,4 +1,10 @@
 module Pricing
+  class DraftOffer < Infra::Command
+    attribute :order_id, Infra::Types::UUID
+
+    alias aggregate_id order_id
+  end
+
   class AddPriceItem < Infra::Command
     attribute :order_id, Infra::Types::UUID
     attribute :product_id, Infra::Types::UUID

ecommerce/pricing/lib/pricing/events.rb

@@ -1,4 +1,8 @@
 module Pricing
+  class OfferDrafted < Infra::Event
+    attribute :order_id, Infra::Types::UUID
+  end
+
   class CouponRegistered < Infra::Event
     attribute :coupon_id, Infra::Types::UUID
     attribute :name, Infra::Types::String

ecommerce/pricing/lib/pricing/offer.rb

@@ -12,6 +12,10 @@ def initialize(id)
       @state = :draft
     end
 
+    def draft
+      apply OfferDrafted.new(data: { order_id: @id })
+    end
+
     def add_item(product_id, base_price)
       price = @discounts.inject(Discounts::NoPercentageDiscount.new, :add).apply(base_price)
       apply PriceItemAdded.new(
@@ -125,6 +129,9 @@ def expire
 
     private
 
+    on OfferDrafted do |event|
+    end
+
     on PriceItemAdded do |event|
       @list.add_item(event.data.fetch(:product_id), event.data.fetch(:base_price), event.data.fetch(:price))
     end

ecommerce/pricing/lib/pricing/services.rb

@@ -14,6 +14,18 @@ class FreeProductAlreadyMade < StandardError
   class FreeProductNotExists < StandardError
   end
 
+  class DraftOfferHandler
+    def initialize(event_store)
+      @repository = Infra::AggregateRootRepository.new(event_store)
+    end
+
+    def call(cmd)
+      @repository.with_aggregate(Offer, cmd.aggregate_id) do |offer|
+        offer.draft
+      end
+    end
+  end
+
   class SetPercentageDiscountHandler
     def initialize(event_store)
       @repository = Infra::AggregateRootRepository.new(event_store)

ecommerce/pricing/test/draft_offer_test.rb

@@ -0,0 +1,23 @@
+require_relative "test_helper"
+
+module Pricing
+  class DraftOfferTest < Test
+    cover "Pricing*"
+
+    def test_draft_offer
+      order_id = SecureRandom.uuid
+      stream = "Pricing::Offer$#{order_id}"
+
+      assert_events(
+        stream,
+        OfferDrafted.new(data: { order_id: order_id })
+      ) { draft_offer(order_id) }
+    end
+
+    private
+
+    def draft_offer(order_id)
+      run_command(DraftOffer.new(order_id: order_id))
+    end
+  end
+end