Testing unmarshalling of asynchronous ActionMailer methods using Sidekiq

Question

TLDR; How can I test that a PORO argument for an asynchronous ActionMailer action (using Sidekiq) serializes and deserializes correctly?

Sidekiq provides RSpec matchers for testing that a job is enqueued and performing a job (with given arguments).

--

To give you some context, I have a Ruby on Rails 4 application with an ActionMailer. Within the ActionMailer is a method that takes in a PORO as an argument - with references to data I need in the email. I use Sidekiq to handle the background jobs. It turns out that there was an issue in deserializing the argument that it would fail when Sidekiq decided to perform the job. I haven't been able to find a way to test the correctness of the un/marshaling such that the PORO I called the action with is being used when performed.

For example:

Given an ActionMailer with an action

class ApplicationMailer < ActionMailer::Base
    def send_alert profile
        @profile = profile
        mail(to: profile.email)
    end
end

...

I would use it like this

profile = ProfileDetailsService.new(user)
ApplicationMailer.send_alert(profile).deliver_later

...

And have a test like this (but this fails)

let(:profile) { ProfileDetailsService.new(user) }

it 'request an email to be sent' do
  expect {
    ApplicationMailer.send_alert(profile).deliver_later
  }.to have_enqueued_job.on_queue('mailers')
end

Any assistance would be much appreciated.

Answer 1

You can test it in a synchronous way (using only IRB and without the need of start the Sidekiq workers).

Let's say your worker class has the following implementation:

class Worker
  include Sidekiq::Worker

  def perform(poro_obj)
    puts poro_obj.inspect
    # ...
  end
end

You can open IRB (bundle exec irb) and type the following commands:

require 'sidekiq'
require 'worker'

Worker.new.perform

Thus, you will execute the code in a synchronous way AND using Sidekiq (note that we're invoking the perform method instead of the perform_async).

I think this is the best way to debug your code.