Rails - framework for sending test emails and disable DB write

Question

I have a website with several types of customer (eg Admin, Manager, Marketing, etc.)

Using Rails, I am asked to send test emails to those people so they can preview the emails on their own email client + firewall restrictions + see if the email go into the promotion folder or not. I need to be able to send a specific set of emails to each user type (such tests are very seldom, but ultimately any of our company admins should be able to send test emails using the frontend interface).

What I'm going for, it to write one class per user type, that would register the emails that this user is likely to receive at some point, and use (for example FactoryGirl) in build-only mode (no Writes to DB !!) to build the models needed to send the emails using deliver_now (so I avoid serialization/deserialization issues). I was hoping to be able to run this system in my real production environment (so that I can use my REAL email reputation, signatures, etc.)

Is there an easy way to disable DB writes (so I make sure all my example models are destroyed after their use to send an email ?) ? An easy option would be to boot up the server using readonly database credentials but maybe there is something safe that would avoid too much trouble.

Here is how my code looks like

module Testing
  module Emails
    class UserTypeAdmin < Base
      attr_accessor, :new_user, :admin
      register_email :created_new_user, type: :user_management do
        UserManagementMailer.user_created(new_user, creator: admin)
      end

      def prepare_models
        self.admin = FactoryGirl.build(:admin)
        self.new_user = FactoryGirl.build(:user)
      end
    end
  end
end

module Testing
  module Emails
    class Base
      class < self
        # my logic to register emails, definitions of #register_email, etc.
      end

      def initialize(tester_emails, ccs = []) 
        @tester_emails = tester_emails
        @ccs = ccs
        prepare_models
      end

      def send_email(email_name)
        email = instance_eval(registered_emails(email_name))
        email.to = @tester_emails
        email.cc = @ccs
        email.deliver_now
      end

My FactoryGirls factories are quite messy and although I am using the :build methods, some factories were written using associations with the :create strategy so just to make sure, I'd like to lock the DB writes so I can easily prevent bad noise on my Database (I am using Mongoid so I don't have an easy transaction mechanism to cancel all my writes)

Answer 1

So one very simple solution is to write a spec that checks nothing is written to the DB. Using this I was able to debug a few cases where one model was persisted.

require 'rails_helper'

describe Testing::Email::UserTypeAdmin do
  let(:tos) { ['[email protected]'] }
  let(:ccs) { ['[email protected]'] }
  let(:tested_models) {[
    User, Admin, 
    Conversation, Message, # etc.
  ]}

  subject do
    described_class.new(tos, ccs)
  end

  context 'testing all emails' do
    it 'does nothing with the DB' do
      subject.send_all_emails
      aggregate_failures 'no persistence' do
        tested_models.each do |model|
          expect(model.count).to eq(0), "#{model.name} was persisted"
        end
      end
    end
  end
end

I'm still on the lookout for better solutions :-)