Profile ActiveRecord queries with RSpec

spec_helper.rb

RSpec.configure do |config|
  config.before(:suite) do
    Thread.current[:query_counter] = Hash.new(0)
  end

  config.around(:example) do |procsy|
    callback = lambda do |*args|
      event = ActiveSupport::Notifications::Event.new(*args)
      sql = event.payload[:sql].to_s.strip
      operation = sql.split(' ', 2).first.to_s.downcase

      next unless operation.present?
      next if event.payload[:name] == “SCHEMA”
      next if event.payload[:name].nil?

      Thread.current[:query_counter][procsy.location] += 1
    end

    ActiveSupport::Notifications
      .subscribed(callback, “sql.active_record”) { procsy.run }
  end

  config.after(:suite) do
    puts
    puts "ActiveRecord queries performed:"

    sorted = Thread.current[:query_counter].sort_by { |location, count| count }.reverse

    sorted.each do |location, count| 
      puts “#{count}: #{location}”
    end
  end
end