Start moving backorder logic to service

The job class is getting too big.

app/jobs/backorder_job.rb

@@ -7,7 +7,6 @@ class BackorderJob < ApplicationJob
   FDC_SALE_SESSION_URL = "#{FDC_BASE_URL}/SalesSession/#".freeze
 
   # The FDC implementation needs special ids for new objects:
-  FDC_NEW_ORDER_URL = "#{FDC_ORDERS_URL}/#".freeze
   FDC_ORDER_LINES_URL = "#{FDC_ORDERS_URL}/#/OrderLines".freeze
 
   queue_as :default
@@ -32,7 +31,7 @@ class BackorderJob < ApplicationJob
   end
 
   def self.place_backorder(order, linked_variants)
-    backorder = build_order(order)
+    backorder = FdcBackorderer.new.find_or_build_order(order)
     catalog = load_catalog(order.distributor.owner)
 
     linked_variants.each_with_index do |variant, index|
@@ -63,11 +62,6 @@ class BackorderJob < ApplicationJob
     end
   end
 
-  # This needs to find an existing order when the API is available.
-  def self.build_order(ofn_order)
-    OrderBuilder.new_order(ofn_order, FDC_NEW_ORDER_URL)
-  end
-
   def self.build_order_line(offer, quantity)
     OrderLineBuilder.build(offer, quantity)
   end

app/services/fdc_backorderer.rb

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+# Place and update orders based on missing stock.
+class FdcBackorderer
+  FDC_BASE_URL = "https://env-0105831.jcloud-ver-jpe.ik-server.com/api/dfc/Enterprises/test-hodmedod"
+  FDC_ORDERS_URL = "#{FDC_BASE_URL}/Orders".freeze
+  FDC_NEW_ORDER_URL = "#{FDC_ORDERS_URL}/#".freeze
+
+  def find_or_build_order(ofn_order)
+    OrderBuilder.new_order(ofn_order, FDC_NEW_ORDER_URL)
+  end
+end

spec/services/fdc_backorderer_spec.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe FdcBackorderer do
+  let(:order) { create(:completed_order_with_totals) }
+
+  describe "#find_or_build_order" do
+    it "builds an order object" do
+      backorder = subject.find_or_build_order(order)
+
+      expect(backorder.semanticId).to match %r{^https.*/\#$}
+      expect(backorder.lines).to eq []
+    end
+  end
+end