Rails%203%20In%20Action

464 CHAPTER 16 Basic performance enhancements
When a worker reads this row, it will convert this marshalled object back into a real
object and then call the perform method on it. The reason for making another class
and using a Struct over using one such as the Comment is that a Struct object will
always be lighter than a full-on class that inherits from ActiveRecord::Base. If you
enqueued a Comment object instead, the result would be this:
"--- !ruby/
ActiveRecord:Comment \nattributes: \n text: This is a comment\n ticket
_id: 1\n user_id: 2\n created_at: &id001 2011-04-
21 09:35:20.497749 Z\n updated_at: *id001\n state_id: \n previous_sta
te_id: \n id: 1\n"
This contains a lot of useless information that you don’t care about when you’re
enqueueing the job, and so you should not use it. When enqueueing jobs, you should
always try for the lightest possible solution so that the job is queued quickly.
Now when a comment is created, a job will be enqueued to notify the watchers of
the relevant ticket. This job is actually a record in a table called delayed_jobs that the
worker reads from, running each job one at a time and working them off the queue.
When there are no more jobs, it will simply wait.
To make sure that this is working, you’re going to write a test for it. The test should
check that a job is enqueued when a comment is created and that the watchers of the
comment’s ticket are notified by email when the job is run. Primarily, this test will
check the perform method in the Comment model, and so you’ll put it in spec/models/
comment_spec.rb, using the code shown in the following listing.
Listing 16.7 spec/models/comment_spec.rb
require 'spec_helper'
describe Comment do
let(:user) { Factory(:user) }
before do
@ticket = Factory(:ticket)
@ticket.watchers "This is a comment",
:user => ticket.user)
Delayed::Job.count.should eql(1)
Delayed::Worker.new.work_off!
Delayed::Job.count.should eql(0)
email = ActionMailer::Base.deliveries.last
email.to.should eql(user.email)
end
end
At the beginning of the describe Comment block, you set up a user who will be the
one to watch the ticket that you set up in the before block.