EmailQueue for Sidekiq

email_queue.rb

class EmailQueue
  include Sidekiq::Worker

  def perform(options)
    mailer  = options['mailer'].constantize
    method = options['method']
    args = options['args']
    mailer.send(method, *args).deliver
  end

  def self.enqueue(mailer_klass, method, *args)
    options = {'mailer' => mailer_klass.to_s, 'method' => method, 'args' =>  args}
    self.perform_async(options)
  end
end

matcher.rb

RSpec::Matchers.define :have_queued_email do |expected|
  match do |actual|
    EmailQueue.jobs.any?{|job| job['args'] == [expected.merge('mailer' => actual.to_s)]}
  end
end