code: func WithProcfileApp(f func(dir string)) {
  	dir, err := ioutil.TempDir("", "simple-ruby-app")
  	Expect(err).ToNot(HaveOccurred())
  	defer os.RemoveAll(dir)
  
  	err = ioutil.WriteFile(filepath.Join(dir, "Procfile"), []byte(`---
  web: ruby -run -e httpd . -p $PORT
  console: bundle exec irb`,
  	), 0666)
  	Expect(err).ToNot(HaveOccurred())
  
  	err = ioutil.WriteFile(filepath.Join(dir, "Gemfile"), nil, 0666)
  	Expect(err).ToNot(HaveOccurred())
  
  	err = ioutil.WriteFile(filepath.Join(dir, "Gemfile.lock"), []byte(`
  GEM
    specs:
  
  PLATFORMS
    ruby
  
  DEPENDENCIES
  
  BUNDLED WITH
     1.15.0
  	`), 0666)
  	Expect(err).ToNot(HaveOccurred())
  
  	f(dir)
  }
docs: // WithProcfileApp creates an application to use with your CLI command
  // that contains Procfile defining web and worker processes.