process_parallel.rb

###
# Execute tests in parallel using multiple processes.  Uses DRb to communicate
# between processes over a unix socket.

gem 'minitest', '~> 5.1.0'
require 'minitest'
require 'minitest/spec'
require 'minitest/mock'
require 'drb'
require 'drb/unix'
require 'tempfile'

class AaronTest < Minitest::Test
  parallelize_me!

  10.times do |i|
    define_method("test_#{i}") {
      #p "process: #{$$}"
      sleep(1); assert true
    }
  end
end

class ForkingExecutor
  class Server
    include DRb::DRbUndumped

    def initialize
      @queue = Queue.new
    end

    def record reporter, result
      reporter.synchronize { reporter.record result }
    end

    def << o; @queue << o; end
    def pop; @queue.pop; end
  end

  def initialize size
    @size  = size
    @queue = Server.new
    file   = File.join Dir.tmpdir, Dir::Tmpname.make_tmpname('tests', 'fd')
    @url   = "drbunix://#{file}"
    DRb.start_service @url, @queue
    @pool  = size.times.map {
      fork {
        DRb.stop_service
        queue = DRbObject.new_with_uri @url
        while job = queue.pop
          klass    = job[0]
          method   = job[1]
          reporter = job[2]
          result = Minitest.run_one_method klass, method
          queue.record reporter, result
        end
      }
    }
  end

  def << work; @queue << work; end
  def shutdown
    @size.times { @queue << nil }
    @pool.each { |pid| Process.waitpid pid }
  end
end

# Use N processes (N defaults to 4)
Minitest.parallel_executor = ForkingExecutor.new((ENV['N'] || 4).to_i)
Minitest.autorun