implement display_line_items_taxes to render included & added tax

app/helpers/tax_helper.rb

@@ -12,6 +12,16 @@ module TaxHelper
     end
   end
 
+  def display_line_items_taxes(line_item, display_zero: true)
+    if line_item.included_tax.positive?
+      Spree::Money.new(line_item.included_tax, currency: line_item.currency)
+    elsif line_item.added_tax.positive?
+      Spree::Money.new(line_item.added_tax, currency: line_item.currency)
+    elsif display_zero
+      Spree::Money.new(0.00, currency: line_item.currency)
+    end
+  end
+
   def display_total_with_tax(taxable)
     total = taxable.amount + taxable.additional_tax_total
     Spree::Money.new(total, currency: taxable.currency)

app/models/spree/line_item.rb

@@ -186,6 +186,10 @@ module Spree
       adjustments.tax.inclusive.sum(:amount)
     end
 
+    def added_tax
+      adjustments.tax.additional.sum(:amount)
+    end
+
     def tax_rates
       product.tax_category&.tax_rates || []
     end

app/views/spree/admin/orders/_invoice_table.html.haml

@@ -20,7 +20,7 @@
         %td{:align => "right"}
           = item.quantity
         %td{:align => "right"}
-          = item.included_tax > 0 ? item.display_included_tax : ""
+          = display_line_items_taxes(item)
         %td{:align => "right"}
           = item.display_amount_with_adjustments
       

spec/helpers/tax_helper_spec.rb

@@ -4,18 +4,24 @@ require 'spec_helper'
 
 describe TaxHelper, type: :helper do
   let(:line_item) { create(:line_item) }
+  let(:line_item2) { create(:line_item) }
+  let(:line_item3) { create(:line_item) }
   let!(:tax_rate) { create(:tax_rate, amount: 0.1) }
   let!(:tax_rate2) { create(:tax_rate, amount: 0.2, included_in_price: false) }
   let!(:included_tax_adjustment) {
     create(:adjustment, originator: tax_rate, adjustable: line_item, state: "closed")
   }
   let!(:additional_tax_adjustment) {
-    create(:adjustment, originator: tax_rate2, adjustable: line_item, state: "closed")
+    create(:adjustment, originator: tax_rate2, adjustable: line_item2, state: "closed")
   }
   let!(:no_tax_adjustment) {
-    create(:adjustment, amount: 0, adjustable: line_item, state: "closed")
+    create(:adjustment, amount: 0, adjustable: line_item3, state: "closed")
   }
 
+  before do
+    included_tax_adjustment.update(included: true)
+  end
+
   describe "#display_taxes" do
     it "displays included tax" do
       expect(
@@ -42,6 +48,26 @@ describe TaxHelper, type: :helper do
     end
   end
 
+  describe "#display_line_items_taxes" do
+    it "displays included tax" do
+      expect(
+        helper.display_line_items_taxes(line_item)
+      ).to eq Spree::Money.new(line_item.included_tax, currency: line_item.currency)
+    end
+
+    it "displays additional tax" do
+      expect(
+        helper.display_line_items_taxes(line_item2)
+      ).to eq Spree::Money.new(line_item2.added_tax, currency: line_item2.currency)
+    end
+
+    it "displays formatted 0.00 amount when amount is zero" do
+      expect(
+        helper.display_line_items_taxes(line_item3)
+      ).to eq Spree::Money.new(0.00,)
+    end
+  end
+
   describe "#display_total_with_tax" do
     it "displays total with included tax" do
       expect(