Add registrar language

#640

test/fixtures/registrars.yml

@@ -5,6 +5,7 @@ DEFAULTS: &DEFAULTS
   email: acme@example.com
   code: 1234
   accounting_customer_code: ACCOUNT001
+  language: en
 
 valid:
   <<: *DEFAULTS

test/models/registrar_test.rb

@@ -20,4 +20,22 @@ class RegistrarTest < ActiveSupport::TestCase
     @registrar.validate
     assert @registrar.invalid?
   end
+
+  def test_requires_language
+    @registrar.language = nil
+    @registrar.validate
+    assert @registrar.invalid?
+  end
+
+  def test_has_default_language
+    Setting.default_language = 'en'
+    registrar = Registrar.new
+    assert_equal 'en', registrar.language
+  end
+
+  def test_overrides_default_language
+    Setting.default_language = 'en'
+    registrar = Registrar.new(language: 'de')
+    assert_equal 'de', registrar.language
+  end
 end