使用 specs2 设计复杂的工作流程

Question

开发功能测试我需要模拟一个工作流程，其中一个步骤的结果被用作以下步骤的输入。例子是这样的：

1. 根据给定条件搜索酒店\房间
   • 检查请求是否成功
   • 检查至少有一些结果
2. 从步骤 1 中选择随机房间。
3. 从第 2 步预订房间。
   • 检查请求是否成功
4. 从第 3 步取消预订。
   • 检查请求是否成功

这里的重点是：

• 如果不执行 1，我们就无法执行 3。
• 如果不执行 3，我们就无法执行 4。
• 如果某个步骤失败，我们应该中止该功能

为这种情况制定规范的方法是什么？

Answer 1

最简单的做法是拥有一个表示进程的可变对象和一个sequential 规范：

class HotelSpec extends mutable.Specification { sequential
  val hotel = new HotelProcess

  "get a room available on Monday" >> ifHotelOk {
    val rooms = request(MONDAY)
    hotel.selectedRooms = rooms
    rooms must not beEmpty
  }

  "book the room" >> ifHotelOk {
    val booking = bookRoom(hotel.selectedRooms.head)
    hotel.currentBooking = booking
    booking must beOk
  }

  def ifHotelOk(r: =>Any) = if (hotel.canContinueProcess) {
    try { r; hotel.continueProcess }
    catch { case t: Throwable => hotel.stopProcess; throw t }
  } else skipped("hotel process error in previous steps")
}

[更新]

这是另一种更好地封装 var 的方法：

import org.specs2._
import org.specs2.execute._
import org.specs2.specification.FixtureExample

class HotelSpec extends HotelProcessSpec {
  "get a room available on Monday" >> { hotel: HP =>
    val rooms = request(MONDAY)
    rooms must be empty

    // update the state of the process at the end of the example
    hotel.selectedRoomsAre(rooms)
  }

  // this example will only execute if the previous step was ok
  "book the room" >> { hotel: HP =>
    val booking = bookRoom(hotel.selectedRooms.head)
    booking.booked must beTrue
  }

  val MONDAY = "monday"
  def request(day: String): Seq[Room] = Seq(Room())
  def bookRoom(room: Room) = Booking()
}

/**
 * A specification trait encapsulating the process of booking hotel rooms
 */
trait HotelProcessSpec extends mutable.Specification with FixtureExample[HotelProcess] {
  sequential

  type HP = HotelProcess
  private var hotelProcess = HotelProcess()

  // if the hotelProcess is returned as the last statement of an Example
  // set the new value of the hotelProcess and return Success
  implicit def hotelProcessAsResult: AsResult[HotelProcess] = new AsResult[HotelProcess] {
    def asResult(hp: =>HotelProcess) =
      try { hotelProcess = hp; Success() }
      catch { case t: Throwable => hotelProcess = hotelProcess.stop; throw t }
  }

  /**
   * stop executing examples if one previous step failed
   */
  protected def fixture[R : AsResult](f: HotelProcess => R): Result = {
    if (hotelProcess.continue) {
      val result = AsResult(f(hotelProcess))
      if (!result.isSuccess) hotelProcess = hotelProcess.stop
      result
    }
    else                       skipped(" - SKIPPED: can't execute this step")
  }

}

case class HotelProcess(selectedRooms: Seq[Room] = Seq(), continue: Boolean = true) {
  def stop = copy(continue = false)
  def selectedRoomsAre(rooms: Seq[Room]) = copy(selectedRooms = rooms)
}
case class Room(number: Int = 0)
case class Booking(booked: Boolean = true)