Retrieve the shipping tax on the order instead of calculating it from scratch

lib/open_food_network/sales_tax_report.rb

@@ -16,7 +16,7 @@ module OpenFoodNetwork
       @orders.map do |order|
         totals = totals_of order.line_items
         shipping_cost = shipping_cost_for order
-        shipping_tax = shipping_tax_on shipping_cost
+        shipping_tax = order.shipping_tax
         
         [order.number, order.created_at, totals[:items], totals[:items_total],
          totals[:taxable_total], totals[:sales_tax], shipping_cost, shipping_tax, totals[:sales_tax] + shipping_tax,
@@ -54,14 +54,6 @@ module OpenFoodNetwork
       shipping_cost = shipping_cost.nil? ? 0.0 : shipping_cost
     end
 
-    def shipping_tax_on(shipping_cost)
-      if shipment_inc_vat && shipping_cost.present?
-        (shipping_cost * shipping_tax_rate / (1 + shipping_tax_rate)).round(2)
-      else
-        0
-      end
-    end
-
     def tax_included_in(line_item)
       line_item.adjustments.included_tax.sum &:amount
     end

spec/features/admin/reports_spec.rb

@@ -109,6 +109,8 @@ feature %q{
   end
   
   describe "Sales tax report" do
+    let!(:payment_method) { create(:payment_method, distributors: [user1.enterprises.first]) }
+
     let(:user1) do
       create_enterprise_user(enterprises: [create(:distributor_enterprise)])
     end
@@ -134,6 +136,8 @@ feature %q{
     before do
       Spree::Config.shipment_inc_vat = true
       Spree::Config.shipping_tax_rate = 0.2
+
+      order1.create_shipment!
       order1.finalize!
 
       login_to_admin_as user1

spec/lib/open_food_network/sales_tax_report_spec.rb

@@ -56,24 +56,5 @@ module OpenFoodNetwork
         end
       end
     end
-
-    describe "calculating the shipping tax on a shipping cost" do
-      it "returns zero when shipping does not include VAT" do
-        report.stub(:shipment_inc_vat) { false }
-        report.send(:shipping_tax_on, 12).should == 0
-      end
-
-      it "returns zero when no shipping cost is passed" do
-        report.stub(:shipment_inc_vat) { true }
-        report.send(:shipping_tax_on, nil).should == 0
-      end
-
-
-      it "returns the tax included in the price otherwise" do
-        report.stub(:shipment_inc_vat) { true }
-        report.stub(:shipping_tax_rate) { 0.2 }
-        report.send(:shipping_tax_on, 12).should == 2
-      end
-    end
   end
 end