Process OC emails individually to avoid duplicates

Errors or delays can cause multiple duplicate emails to the same
suppliers.

app/jobs/order_cycle_notification_job.rb

@@ -5,7 +5,7 @@ class OrderCycleNotificationJob < ApplicationJob
   def perform(order_cycle_id)
     order_cycle = OrderCycle.find(order_cycle_id)
     order_cycle.suppliers.each do |supplier|
-      ProducerMailer.order_cycle_report(supplier, order_cycle).deliver_now
+      ProducerMailer.order_cycle_report(supplier, order_cycle).deliver_later
     end
     order_cycle.update_columns mails_sent: true
   end

spec/jobs/order_cycle_notification_job_spec.rb

@@ -4,20 +4,18 @@ require 'spec_helper'
 
 RSpec.describe OrderCycleNotificationJob do
   let(:order_cycle) { create(:order_cycle) }
-  let(:mail) { double(:mail, deliver_now: true) }
-
-  before do
-    allow(ProducerMailer).to receive(:order_cycle_report).twice.and_return(mail)
-  end
 
   it "sends a mail to each supplier" do
-    OrderCycleNotificationJob.perform_now order_cycle.id
-    expect(ProducerMailer).to have_received(:order_cycle_report).twice
+    expect {
+      OrderCycleNotificationJob.perform_now(order_cycle.id)
+    }.to enqueue_mail(ProducerMailer, :order_cycle_report).twice
   end
 
   it "records that mails have been sent for the order cycle" do
-    expect do
+    expect {
       OrderCycleNotificationJob.perform_now(order_cycle.id)
-    end.to change{ order_cycle.reload.mails_sent? }.from(false).to(true)
+    }.to change {
+      order_cycle.reload.mails_sent?
+    }.from(false).to(true)
   end
 end