synchronizer.rb

class Synchronizer
  module ClassMethods
    attr_reader :m, :cv

    def init!
      @m = Mutex.new
      @cv = ConditionVariable.new
    end

    def wait
      m.synchronize { cv.wait(m) }
    end

    def pass
      m.synchronize { cv.signal }
    end
  end

  extend ClassMethods
  init!
end

test.rb

require 'test_helper'
require 'eventmachine'

require 'synchronizer'
require 'socket'

class SichuanTest < Minitest::Test
  module TestServer
    def post_init
      Thread.current[:post_init_received] = true
      Synchronizer.pass
    end

    def receive_data(data)
      Thread.current[:received_data] = data.chomp
      Synchronizer.pass
    end

    def unbind
      Thread.current[:unbind_received] = true
      Synchronizer.pass
    end
  end

  def test_start_server
    thread = Thread.new {
      EventMachine.run {
        EventMachine.start_server '127.0.0.1', 2222, TestServer
        Synchronizer.pass
      }
    }

    Synchronizer.wait

    socket = Socket.new(Socket::AF_INET, Socket::SOCK_STREAM)
    sockaddr = Socket.pack_sockaddr_in(2222, '127.0.0.1')

    assert_equal 0, socket.connect(sockaddr)
    Synchronizer.wait
    assert_equal true, thread[:post_init_received]

    socket.puts 'test-test'
    Synchronizer.wait
    assert_equal 'test-test', thread[:received_data]

    socket.close
    Synchronizer.wait
    assert_equal true, thread[:unbind_received]
  end
end