Always require association

#697

app/models/message.rb

@@ -1,6 +1,6 @@
 class Message < ActiveRecord::Base
   include Versions # version/message_version.rb
-  belongs_to :registrar
+  belongs_to :registrar, required: true
 
   before_create -> { self.queued = true }
 

db/migrate/20180211011450_change_messages_registrar_id_to_not_null.rb

@@ -0,0 +1,5 @@
+class ChangeMessagesRegistrarIdToNotNull < ActiveRecord::Migration
+  def change
+    change_column_null :messages, :registrar_id, false
+  end
+end

db/structure.sql

@@ -2184,7 +2184,7 @@ ALTER SEQUENCE mail_templates_id_seq OWNED BY mail_templates.id;
 
 CREATE TABLE messages (
     id integer NOT NULL,
-    registrar_id integer,
+    registrar_id integer NOT NULL,
     body character varying,
     attached_obj_type character varying,
     attached_obj_id character varying,
@@ -5070,3 +5070,5 @@ INSERT INTO schema_migrations (version) VALUES ('20180126104536');
 
 INSERT INTO schema_migrations (version) VALUES ('20180126104903');
 
+INSERT INTO schema_migrations (version) VALUES ('20180211011450');
+

test/models/message_test.rb

@@ -14,4 +14,10 @@ class MessageTest < ActiveSupport::TestCase
     @message.validate
     assert @message.invalid?
   end
+
+  def test_invalid_without_registrar
+    @message.registrar = nil
+    @message.validate
+    assert @message.invalid?
+  end
 end