Use delegate for finding the tax category of a shipment

core/app/models/spree/shipment.rb

@@ -74,6 +74,8 @@ class Shipment < Spree::Base
     self.whitelisted_ransackable_associations = ['order']
     self.whitelisted_ransackable_attributes = ['number']
 
+    delegate :tax_category, to: :selected_shipping_rate, allow_nil: true
+
     def can_transition_from_pending_to_shipped?
       !requires_shipment?
     end
@@ -244,10 +246,6 @@ def shipping_method
       selected_shipping_rate.try(:shipping_method) || shipping_rates.first.try(:shipping_method)
     end
 
-    def tax_category
-      selected_shipping_rate.try(:tax_rate).try(:tax_category)
-    end
-
     # Only one of either included_tax_total or additional_tax_total is set
     # This method returns the total of the two. Saves having to check if
     # tax is included or additional.

core/app/models/spree/shipping_rate.rb

@@ -5,7 +5,7 @@ class ShippingRate < Spree::Base
     belongs_to :tax_rate, -> { with_deleted }, class_name: 'Spree::TaxRate'
 
     delegate :order, :currency, to: :shipment
-    delegate :name, to: :shipping_method
+    delegate :name, :tax_category, to: :shipping_method
     delegate :code, to: :shipping_method, prefix: true
 
     def display_base_price

core/spec/lib/spree/core/unreturned_item_charger_spec.rb

@@ -1,17 +1,21 @@
 require 'spec_helper'
 
 describe Spree::UnreturnedItemCharger do
-  let(:shipped_order) { create(:shipped_order, line_items_count: 1, with_cartons: false) }
+  let(:ship_address) { create(:address) }
+  let(:shipped_order) { create(:shipped_order, ship_address: ship_address, line_items_count: 1, with_cartons: false) }
   let(:original_shipment) { shipped_order.shipments.first }
   let(:original_stock_location) { original_shipment.stock_location }
   let(:original_inventory_unit) { shipped_order.inventory_units.first }
   let(:original_variant) { original_inventory_unit.variant }
+  let(:shipping_method) { create(:shipping_method, tax_category: original_variant.tax_category) }
+
   let(:exchange_shipment) do
     create(:shipment,
            order: shipped_order,
            state: 'shipped',
            stock_location: original_stock_location,
-           created_at: 5.days.ago)
+           created_at: 5.days.ago,
+           shipping_method: shipping_method)
   end
   let(:exchange_inventory_unit) { exchange_shipment.inventory_units.first }
   let(:return_item) do
@@ -43,12 +47,11 @@
     end
 
     context 'in tax zone' do
-      let!(:tax_zone) { Spree::Zone.find_by(name: 'GlobalZone') || FactoryGirl.create(:global_zone) }
+      let!(:tax_zone) { create(:zone, countries: [ship_address.country]) }
       let!(:tax_rate) { create(:tax_rate, zone: tax_zone, tax_category: original_variant.tax_category) }
       before { tax_zone.update_attributes!(default_tax: true) }
 
       it "applies tax" do
-        exchange_shipment.shipping_rates.update_all(tax_rate_id: tax_rate.id)
         exchange_order = exchange_shipment.order
         exchange_order.create_tax_charge!
         exchange_order.update!

core/spec/models/spree/tax/taxation_integration_spec.rb

@@ -146,7 +146,6 @@
         end
 
         it 'has a shipment with 0.52 included tax' do
-          pending 'But the tax is not created'
           expect(shipment.included_tax_total).to eq(0.52)
         end
 
@@ -182,7 +181,6 @@
         end
 
         it 'has a shipment with 2.55 included tax' do
-          pending 'But the tax is not created'
           expect(shipment.included_tax_total).to eq(2.55)
         end
 
@@ -264,7 +262,6 @@
         end
 
         it 'has a shipment with 0.52 included tax' do
-          pending 'But the tax is not created'
           expect(shipment.included_tax_total).to eq(0.52)
         end
 
@@ -304,7 +301,6 @@
         end
 
         it 'has a shipment with 2.55 included tax' do
-          pending 'But the tax is not created'
           expect(shipment.included_tax_total).to eq(2.55)
         end
 
@@ -770,7 +766,6 @@
         end
 
         it 'has a shipment with additional tax of 0.40' do
-          pending "This does not work because the shipping code does not use contains? for finding zones"
           expect(shipment.additional_tax_total).to eq(0.40)
         end