为什么在Spec2中有时无法捕获异常？

Question

scala测试代码：

import play.api.test._
import scala._
import org.specs2.execute.Result

object ThrowTest extends PlaySpecification {

  "throwA" should {
    "catch the exception test1" in {
      world must throwA[Exception]
    }
    "catch the exception test2" in {
      hello {
        world =>
          world must throwA[Exception]
      }
    }
  }

  def hello(action: (String) => Result) = {
    action(world)
  }

  def world: String = {
    throw new Exception("world-exception")
  }

}

为什么test1像我预期的那样工作，而test2不是，它向外部抛出异常，并且永远不会捕获它：

[info] ! catch the exception test2
[error]     Exception: world-exception (ThrowTest.scala:26)
[error] database.ThrowTest$.world(ThrowTest.scala:26)
[error] database.ThrowTest$.hello(ThrowTest.scala:22)
[error] database.ThrowTest$$anonfun$1$$anonfun$apply$4.apply(ThrowTest.scala:14)
[error] database.ThrowTest$$anonfun$1$$anonfun$apply$4.apply(ThrowTest.scala:14)
[info] Total for specification ThrowTest

Answer 1

因为对于测试2，在调用action之前会从hello抛出异常。action是一个String => Result，你可以用world来调用它，当它被计算时，会抛出一个异常，因此，所有这些代码：

world =>world must throwA[Exception]

永远不会被执行。