Update emails' content

Closes #1127

test/mailers/domain_expire_mailer_test.rb

@@ -0,0 +1,20 @@
+require 'test_helper'
+
+class DomainExpireMailerTest < ActiveSupport::TestCase
+  include ActionMailer::TestHelper
+
+  setup do
+    ActionMailer::Base.deliveries.clear
+  end
+
+  def test_delivers_domain_expiration_email
+    domain = domains(:shop)
+    assert_equal 'shop.test', domain.name
+
+    email = DomainExpireMailer.expired(domain: domain, registrar: domain.registrar).deliver_now
+
+    assert_emails 1
+    assert_equal 'Domeen shop.test on aegunud / Domain shop.test has expired' \
+      ' / Срок действия домена shop.test истек', email.subject
+  end
+end