From 01712b93b484b131a0882a4e41fd9e61d47644c6 Mon Sep 17 00:00:00 2001
From: Valentin Lazar <valentin.lazar.personal.email@gmail.com>
Date: Wed, 17 Dec 2025 16:08:13 +0200
Subject: [PATCH] Add BT-21 field

---
 lib/secretariat/invoice.rb |  4 +++-
 test/invoice_test.rb       | 15 +++++++++++----
 2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/lib/secretariat/invoice.rb b/lib/secretariat/invoice.rb
index 8a8f42a..94826e3 100644
--- a/lib/secretariat/invoice.rb
+++ b/lib/secretariat/invoice.rb
@@ -51,7 +51,8 @@ module Secretariat
     :attachments,
     :direct_debit_mandate_reference_id, # BT-89
     :direct_debit_creditor_id, # BT-90
-    :direct_debit_iban, # BT-91
+    :direct_debit_iban, # BT-91,
+    :subject_code, # BT-21
     keyword_init: true
   ) do
 
@@ -220,6 +221,7 @@ def to_xml(version: 1, validate: true)
             Array(self.notes).each do |note|
               xml['ram'].IncludedNote do
                 xml['ram'].Content note
+                xml['ram'].SubjectCode subject_code if subject_code
               end
             end
           end
diff --git a/test/invoice_test.rb b/test/invoice_test.rb
index 666b1f5..f6e1923 100644
--- a/test/invoice_test.rb
+++ b/test/invoice_test.rb
@@ -56,6 +56,7 @@ def make_eu_invoice(tax_category: :REVERSECHARGE, ship_to: nil)
         paid_amount: 29,
         payment_due_date: Date.today + 14,
         notes: "This is a test invoice",
+        subject_code: 'REG' # BT-21
       )
     end
 
@@ -111,6 +112,7 @@ def make_eu_invoice_with_line_item_billing_period(tax_category: :REVERSECHARGE)
         paid_amount: 29,
         payment_due_date: Date.today + 14,
         notes: "This is a test invoice",
+        subject_code: 'REG' # BT-21
       )
     end
 
@@ -169,6 +171,7 @@ def make_eu_invoice_with_sepa_direct_debit(tax_category: :REVERSECHARGE)
         direct_debit_mandate_reference_id: "MANDATE REFERENCE", # BT-89
         direct_debit_creditor_id: "DE98ZZZ09999999999", # BT-90
         direct_debit_iban: "DE02120300000000202051", # BT-91
+        subject_code: 'REG' # BT-21
 
       )
     end
@@ -218,7 +221,8 @@ def make_foreign_invoice(tax_category: :TAXEXEMPT)
         grand_total_amount: BigDecimal('29'),
         due_amount: 0,
         paid_amount: 29,
-        payment_due_date: Date.today + 14
+        payment_due_date: Date.today + 14,
+        subject_code: 'REG' # BT-21
       )
     end
 
@@ -275,7 +279,8 @@ def make_eu_invoice_with_attachment
         due_amount: 0,
         paid_amount: 29,
         payment_due_date: Date.today + 14,
-        attachments: [attachment]
+        attachments: [attachment],
+        subject_code: 'REG' # BT-21
       )
     end
 
@@ -333,7 +338,8 @@ def make_de_invoice
         grand_total_amount: BigDecimal('23.80'),
         due_amount: 0,
         paid_amount: BigDecimal('23.80'),
-        payment_due_date: Date.today + 14
+        payment_due_date: Date.today + 14,
+        subject_code: 'REG' # BT-21
       )
     end
 
@@ -413,7 +419,8 @@ def make_de_invoice_with_multiple_tax_rates
         grand_total_amount: BigDecimal('55.28'),
         due_amount: 0,
         paid_amount: BigDecimal('55.28'),
-        payment_due_date: Date.today + 14
+        payment_due_date: Date.today + 14,
+        subject_code: 'REG' # BT-21
       )
     end