add enum type for tax codes that are applicable on whole invoice when…

… serializing to graphql

app/graphql/types/invoices/applied_taxes/object.rb

@@ -8,8 +8,13 @@ class Object < Types::BaseObject
         implements Types::Taxes::AppliedTax
 
         field :applied_on_whole_invoice, GraphQL::Types::Boolean, null: false, method: :applied_on_whole_invoice?
+        field :enumed_tax_code, Types::Invoices::AppliedTaxes::WholeInvoiceApplicableTaxCodeEnum, required: false
         field :fees_amount_cents, GraphQL::Types::BigInt, null: false
         field :invoice, Types::Invoices::Object, null: false
+
+        def enumed_tax_code
+          object.tax_code if object.applied_on_whole_invoice?
+        end
       end
     end
   end

app/graphql/types/invoices/applied_taxes/whole_invoice_applicable_tax_code_enum.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+module Types
+  module Invoices
+    module AppliedTaxes
+      class WholeInvoiceApplicableTaxCodeEnum < Types::BaseEnum
+        graphql_name 'InvoiceAppliedTaxOnWholeInvoiceCodeEnum'
+
+        Invoice::AppliedTax::TAX_CODES_APPLICABLE_ON_WHOLE_INVOICE.each do |type|
+          value type
+        end
+      end
+    end
+  end
+end