add adjustables to the list of objects to serialize when creating an invoice

app/models/invoice/data_presenter/adjustable.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: false
+
+class Invoice
+  class DataPresenter
+    class Adjustable  < Invoice::DataPresenter::Base
+      attributes :id, :type, :currency, :included_tax_total, :additional_tax_total, :amount
+
+      def display_taxes(display_zero: false)
+        if included_tax_total.positive?
+          amount = Spree::Money.new(included_tax_total, currency: currency)
+          I18n.t(:tax_amount_included, amount: amount)
+        elsif additional_tax_total.positive?
+          Spree::Money.new(additional_tax_total, currency: currency)
+        elsif display_zero
+          Spree::Money.new(0.00, currency: currency)
+        end
+      end
+
+    end
+  end
+end

app/models/invoice/data_presenter/adjustment.rb

@@ -7,7 +7,8 @@ class Invoice
       attributes :additional_tax_total, :adjustable_type, :amount, :currency, :included_tax_total,
                  :label
       array_attribute :tax_rates, class_name: 'TaxRate'
-      attributes_with_presenter :originator, class_name: :AdjustmentOriginator
+      attributes_with_presenter :originator, class_name: 'AdjustmentOriginator'
+      attributes_with_presenter :adjustable
       invoice_generation_attributes :additional_tax_total, :adjustable_type, :amount,
                                     :included_tax_total
       invoice_update_attributes :label

app/serializers/invoice/adjustable_serializer.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: false
+
+class Invoice
+  class AdjustableSerializer < ActiveModel::Serializer
+    attributes :id, :type, :currency, :included_tax_total, :additional_tax_total, :amount
+    def type
+      object.class.name
+    end
+
+    [:currency, :included_tax_total, :additional_tax_total, :amount].each do |method|
+      define_method method do
+        return nil unless object.respond_to?(method)
+
+        object.public_send(method).to_f
+      end
+    end
+  end
+end

app/serializers/invoice/adjustment_serializer.rb

@@ -5,6 +5,7 @@ class Invoice
     attributes :adjustable_type, :label, :included_tax_total, :additional_tax_total, :amount,
                :currency
     has_one :originator, serializer: Invoice::AdjustmentOriginatorSerializer
+    has_one :adjustable, serializer: Invoice::AdjustableSerializer
     has_many :tax_rates, serializer: Invoice::TaxRateSerializer
 
     def tax_rates

app/views/spree/admin/orders/_invoice_table3.html.haml

@@ -25,14 +25,14 @@
           = item.display_amount_with_adjustments
       
     - @order.checkout_adjustments(exclude: [:line_item]).reverse_each do |adjustment|
-      - taxable = adjustment#.adjustable_type == "Spree::Shipment" ? adjustment.adjustable : adjustment
+      - taxable = adjustment.adjustable_type == "Spree::Shipment" ? adjustment.adjustable : adjustment
       %tr
         %td
           %strong= "#{raw(adjustment.label)}"
         %td{:align => "right"}
           1
         %td{:align => "right"}
-          = adjustment.display_taxes
+          = taxable.display_taxes
         %td{:align => "right"}
           = adjustment.display_amount
   %tfoot