When creating Order, correctly assign ship_address or use_billing

The Order should use_billing == true if ship_address is missing, is empty, or is the same as bill_address

core/app/models/spree/order.rb

@@ -151,7 +151,7 @@ def states
     before_validation :ensure_currency_presence
 
     before_validation :clone_billing_address, if: :use_billing?
-    attr_accessor :use_billing
+    attr_writer :use_billing
 
     before_create :create_token
     before_create :link_by_email
@@ -299,6 +299,9 @@ def associate_user!(user, override_email = true)
       self.created_by   ||= user
       self.bill_address_id ||= user.bill_address_id
       self.ship_address_id ||= user.ship_address_id
+      if ship_address_id == bill_address_id
+        self.ship_address_id = nil
+      end
 
       changes = slice(:user_id, :email, :created_by_id, :bill_address_id, :ship_address_id)
 
@@ -557,10 +560,6 @@ def refresh_shipment_rates(shipping_method_filter = ShippingMethod::DISPLAY_ON_F
       shipments.map { |s| s.refresh_rates(shipping_method_filter) }
     end
 
-    def shipping_eq_billing_address?
-      bill_address == ship_address
-    end
-
     def set_shipments_cost
       shipments.each(&:update_amounts)
       updater.update_shipment_total
@@ -689,6 +688,12 @@ def has_free_shipping?
               spree_promotion_actions: { type: 'Spree::Promotion::Actions::FreeShipping' }).exists?
     end
 
+    def use_billing
+      @use_billing.in?([true, 'true', '1']) ||
+        ship_address.nil? || ship_address.empty? ||
+        ship_address == bill_address
+    end
+
     private
 
     def link_by_email
@@ -732,7 +737,7 @@ def after_resume
     end
 
     def use_billing?
-      use_billing.in?([true, 'true', '1'])
+      use_billing
     end
 
     def ensure_currency_presence

core/spec/models/spree/order_spec.rb

@@ -1228,11 +1228,11 @@ def attributes(amount = 0)
     end
   end
 
-  describe '#shipping_eq_billing_address' do
+  describe '#use_billing' do
     let!(:order) { create(:order) }
 
     context 'with only bill address' do
-      it { expect(order.shipping_eq_billing_address?).to eq(false) }
+      it { expect(order.use_billing).to eq(true) }
     end
 
     context 'blank addresses' do
@@ -1241,7 +1241,7 @@ def attributes(amount = 0)
         order.ship_address = Spree::Address.new
       end
 
-      it { expect(order.shipping_eq_billing_address?).to eq(true) }
+      it { expect(order.use_billing).to eq(true) }
     end
 
     context 'no addresses' do
@@ -1250,7 +1250,7 @@ def attributes(amount = 0)
         order.ship_address = nil
       end
 
-      it { expect(order.shipping_eq_billing_address?).to eq(true) }
+      it { expect(order.use_billing).to eq(true) }
     end
   end