Add async steps in specs2

afterEachAsync.scala

import org.specs2.specification.create._
import org.specs2.control.producer.Producer._

/** How to add an async action after each example */
trait AfterEachAsync extends org.specs2.mutable.Specification:
  override def map(fs: =>Fragments): Fragments =
    super.map(fs.flatMap { f =>
      if Fragment.isExample(f) then
        emitAsync(List(f, step(afterAsync)))
      else
        emitAsync(List(f))
    })

  protected def afterAsync: Any

/**
  This spec shows how it works.
  
  It prints out something like
  
  e1 specs2-3
  after example 1 specs2-2
  e2 specs2-5
  after example 2 specs2-11
  e3 specs2-2
  after example 3 specs2-8
  
  So that the execution of both examples and steps gets dispatched to different threads
  
  but the intended order of having 1 example followed by 1 step, then 1 example etc...
  is maintained
 */
class TestMutableSpec extends org.specs2.mutable.Specification with AfterEachAsync:
  var i = 1
  def afterAsync: Any =
    Thread.sleep(500)
    println("after example " + i + " " + Thread.currentThread.getName)
    i = i + 1

  "e1" >> { println("e1 "+Thread.currentThread.getName); success }
  "e2" >> { println("e2 "+Thread.currentThread.getName); success }
  "e3" >> { println("e3 "+Thread.currentThread.getName); success }