How to automate testing successful boot of Sidekiq Process - ruby-on-rails

Question

We've had a couple of issues recently in our Rails 4 app that could have been prevented with a simple check to see that both the main app and a worker process correctly boot up our application.
Our Procfile for Heroku looks like so:
web: bundle exec unicorn -p $PORT -c config/heroku/unicorn.rb
sidekiq: bundle exec sidekiq -q high -q medium -q low
Right now, we run a very large test suite that takes 30 mins to complete, even when bisecting the suite across 10+ containers.
We use CircleCI and are considering adding a test like follows that simulates the Sidekiq bootup process.
require 'spec_helper'
RSpec.describe 'Booting processes' do
context 'Sidekiq server' do
it 'loads successfully' do
boot_sidekiq_sequence = <<-SEQ
require 'sidekiq/cli'
Sidekiq::CLI.instance.environment = '#{ENV['RAILS_ENV']}'
Sidekiq::CLI.instance.send(:boot_system)
SEQ
expect(system(%{echo "#{boot_sidekiq_sequence}" | ruby > /dev/null})).to be_truthy,
"The Sidekiq process could not boot up properly. Run `sidekiq` to troubleshoot"
end
end
end
The problem with this is that:
It's not quite a complete test of our application boot process which would require reading from our Procfile (we also want to protect devs from making breaking changes there)
It's slow and would add approx 30 secs to our test runtime
It's a bit low-level for my liking.
What makes testing the Sidekiq boot process in particular challenging is that it will only exit if there is an exception on boot.
Can anyone recommend a better, faster, more thorough approach to automating this kind of test?

Answer 1

For integration testing, it's always best to run the process as close to production as possible, so bundle exec sidekiq .... I wouldn't use the CLI API to boot it in-process.
I would first enqueue a special job which just does this:
def perform
puts "Sidekiq booted"
Process.kill($$, TERM) # terminate ourselves
end
Then execute Sidekiq by running the binary and monitoring STDOUT. If you see /booted/ within 30 seconds, PASS. If you see nothing within 30 seconds, FAIL and kill the child.

Answer 2

Thanks to the inspiration here I ended up with a test that executes the actual command from the Procfile:
require 'foreman/procfile'
require 'open3'
# Utilizes a Procfile like this:
# web: bundle exec puma -C config/puma.rb
# workers: bundle exec sidekiq
#
describe Sidekiq do
let(:procfile_name){ 'Procfile' }
let(:command_name){ 'workers' }
let(:command){ Foreman::Procfile.new(procfile_name)[command_name] || raise("'#{command_name}' not defined in '#{procfile_name}'") }
it 'launches without errors' do
expect(output_from(command)).to match(/Starting processing/)
end
def output_from(command)
Open3.popen2e(*command.split) do |_, out, wait_thr|
pid = wait_thr.pid
output_pending = IO.select([out], nil, nil, 10.seconds)
Process.kill 'TERM', pid
if output_pending
out.read
else
raise Timeout::Error
end
end
end
end