Imagining async rack-test

async-rack.rb

require 'rubygems'
require 'bundler'
Bundler.setup
require 'rack'
require 'rack/test'
require 'benchmark'

class Foo
  def self.call(env)
    sleep 1
    [200, {'Content-Type' => 'text/plain'}, 'OK']
  end
end

class AsyncApp
  def initialize(app)
    @app = app
    @fds = {}
    at_exit { run }
  end

  def call(env, &callback)
    rd, wr = IO.pipe
    fork do
      rd.close
      response = @app.call(env)
      wr.write response
      wr.close
      exit!
    end
    wr.close
    @fds[rd] = callback
  end

  def run
    until @fds.empty?
      reads = select(@fds.keys).first
      reads.each do |io|
        if io.eof?
          @fds.delete(io)
        else
          @fds[io].call(io.read)
        end
      end
    end
  end
end

class AsyncTest
  def app
    @app ||= Rack::Builder.new do
      run Foo
    end
  end

  def async_app
    @async_app ||= AsyncApp.new(app)
  end

  def async
    env = Rack::MockRequest.env_for
    async_app.call(env) { |resp|
      p resp
    }
  end
end

test = AsyncTest.new
test.async