Require registrar's accounting customer code

#343

test/integration/admin/registrars/new_registrar_test.rb

@@ -13,6 +13,7 @@ class NewRegistrarTest < ActionDispatch::IntegrationTest
     fill_in 'registrar[reg_no]', with: '1234567'
     fill_in 'registrar[email]', with: 'test@test.com'
     fill_in 'registrar[code]', with: 'test'
+    fill_in 'registrar[accounting_customer_code]', with: 'test'
     click_link_or_button 'Create registrar'
 
     assert_text 'Registrar has been successfully created'

test/models/registrar_test.rb

@@ -0,0 +1,9 @@
+require 'test_helper'
+
+class RegistrarTest < ActiveSupport::TestCase
+  def test_rejects_absent_accounting_customer_code
+    registrar = Registrar.new(accounting_customer_code: nil)
+    registrar.validate
+    assert registrar.errors.added?(:accounting_customer_code, :blank)
+  end
+end