RSpecで外部プロセスを必要とするテスト実行するためのスニペット

# spec/support下に配置しておく

# @param [Hash] options Any of :log, :env, :pwd, :command, :stdout_log, :stderr_log, :spawn_options, :spawn_checker, :timeout
def spawn_process(options = {})
  env = options[:env] || {}
  command = options[:command]
  stdout_log = options[:stdout_log] ? [options[:stdout_log], 'w'] : :out
  stderr_log = options[:stderr_log] ? [options[:stderr_log], 'w'] : :err
  pwd = options[:pwd]
  spawn_options = {
    :out => stdout_log,
    :err => stderr_log,
  }
  spawn_options.merge!(:chdir => pwd) if pwd
  spawn_options.merge!(options[:spawn_options]) if options[:spawn_options]
  spawn_checker = options[:spawn_checker]
  timeout_sec = options[:timeout] || 30

  ::ActiveRecord::Base.clear_all_connections!
  pid = spawn(env, command, spawn_options)
  ::ActiveRecord::Base.establish_connection

  at_exit do
    begin
      Process.kill(:SIGINT, pid)
      Process.waitpid(pid)
    rescue Errno::ESRCH, Errno::ECHILD
    end
  end

  if spawn_checker
    begin
      timeout(timeout_sec) do
        until spawn_checker.call
          Process.kill 0, pid # live check. Raise Errno::ESRCH if process died
          sleep 0.1
        end
      end
    rescue Timeout::Error, Errno::ESRCH
      STDERR.puts("Failed to start the backend program #{options.inspect}")
      if File.exist?(stdout_log)
        STDERR.puts(File.read(stdout_log))
      end
    end
  end

  pid
end

# spec_helperの例

  config.before(:each, redis: true) do
    unless $redis_pid
      $redis_pid = spawn_process(
        command: "redis-server #{Rails.root.join('spec', 'redis_test.conf')}",
        spawn_checker: -> { sleep 0.2; true },
      )
    end
    Redis.new(url: redis_url).flushall
  end

  config.before(:each, sidekiq: true) do
    Sidekiq::Testing.disable!

    unless $sidekiq_pid
      log = Rails.root.join('log', 'sidekiq_test.log').to_s
      $sidekiq_pid = spawn_process(
        command: "bundle exec sidekiq -q seirenes -c 1",
        env: {"REDIS_PORT" => "6380"},
        stdout_log: log,
        spawn_checker: -> { File.read(log) =~ /Starting processing/ },
      )
    end
  end

  config.after(:each, sidekiq: true) do
    Sidekiq::Testing.fake!
  end