Gold Master Test and Rake Task: https://hashrocket.com/blog/posts/gold-master-testing

gold.rake

namespace :gold do
  desc "DATABASE will be used to generate the new gold master database"
  task :update_db do
    db_name = ENV.fetch('DATABASE') { Rails.configuration.database_configuration[Rails.env]["database"] }
    destination = Rails.root.join('test/files/gold_master.sql')
    puts "Executing command..."
    sh "pg_dump #{db_name} --data-only --attribute-inserts --column-inserts --no-tablespaces --no-privileges --no-security-labels --disable-triggers > #{destination}"
    puts <<~MSG
      Done!

      ----------------------------------------------------------------------------------------------------
      WARNING: The file generated file below:

      #{destination}

      needs some cleaning up before you can use it on your gold master test/s.

      Specifically, you need to remove a bunch of configuration we don't need at the start,
      it should look something like this:

      ```
      SET statement_timeout = 0;
      SET lock_timeout = 0;
      SET client_encoding = 'UTF8';
      SET standard_conforming_strings = on;
      SELECT pg_catalog.set_config('search_path', '', false);
      SET check_function_bodies = false;
      SET client_min_messages = warning;
      ```

      Also, you'll need to remove INSERT INTO statement/s to the ar_internal_metadata table:

      ```
      ALTER TABLE public.ar_internal_metadata DISABLE TRIGGER ALL;
      INSERT INTO public.ar_internal_metadata (key, value, created_at, updated_at) VALUES ('environment', 'development', '2020-03-20 03:56:06.881918', '2020-03-20 03:56:06.881918');
      ALTER TABLE public.ar_internal_metadata ENABLE TRIGGER ALL;
      ```
      ----------------------------------------------------------------------------------------------------
    MSG
  end
end

gold_master_test.rb

# https://hashrocket.com/blog/posts/gold-master-testing

describe 'gold master' do
  it 'produces a consistent result' do

    ActiveRecord::Base.connection.execute <<-SQL
      truncate schema_migrations;
      #{Rails.root.join('spec/fixtures/gold_master.sql').read}
    SQL

    actual = Transformer.transform

    gold_master_file = Rails.root.join('spec/fixtures/gold_master.txt')
    gold_master = gold_master_file.read

    if gold_master != actual
      gold_master_file.write(actual)
    end

    expect(actual).to eq(gold_master)
  end
end