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ScalaTest:在失败的期货中断言异常(非阻塞)

分类: 技术问答 • 2022-05-27 10:20:07
问题描述：

import org.scalatest.{ FlatSpec, Matchers, ParallelTestExecution }
import org.scalatest.concurrent.ScalaFutures
import org.apache.thrift.TApplicationException

class Test extends FlatSpec with Matchers with ScalaFutures with ParallelTestExecution {
  it should "throw org.apache.thrift.TApplicationException for invalid Ids" in {
    val future: Future[Response] = ThriftClient.thriftRequest
    whenReady(future) {
      res => {
       intercept[TApplicationException] {
       }
      }
    }
  }
}

问题:如何在不阻塞的情况下断言 Futures 中的预期失败?以上不起作用，在 intercept 块之前抛出异常.

Question: How do you assert expected failures in Futures without blocking? The above doesn't work, the exception is thrown before the intercept block.

答

注意:保留这个答案是因为 OP 发现它有帮助，但对于 Scala Futures，请参阅另一个答案.

这有点像样板，但是 Waiter 来自 AsyncAssertions:

import org.scalatest.{ FlatSpec, Matchers, ParallelTestExecution }
import org.scalatest.concurrent.{ ScalaFutures, AsyncAssertions, PatienceConfiguration }
import concurrent.Future
import concurrent.ExecutionContext.Implicits._
import util._ 

class Test extends FlatSpec with Matchers with ScalaFutures with ParallelTestExecution with AsyncAssertions {
  it should "throw for invalid Ids" in {
    val f: Future[Int] = new Goof().goof
    val w = new Waiter
    f onComplete {
      case Failure(e) => w(throw e); w.dismiss()
      case Success(_) => w.dismiss()
    }
    intercept[UnsupportedOperationException] {
      w.await
    }
  }
}

给定

import concurrent.Future
import concurrent.ExecutionContext.Implicits._

class Goof {
  def goof(delay: Int = 1): Future[Int] = Future {
    Thread sleep delay * 1000L
    throw new UnsupportedOperationException
  } 
  def goofy(delay: Int = 1): Future[Int] = Future {
    Thread sleep delay * 1000L
    throw new NullPointerException
  } 
  def foog(delay: Int = 1): Future[Int] = Future {
    Thread sleep delay * 1000L
    7
  }
}

换句话说，

class Test extends FlatSpec with Matchers with ScalaFutures with ParallelTestExecution with AsyncAssertions {
  it should "throw for invalid Ids" in {
    val f: Future[Int] = new Goof().goof
    import Helper._
    f.failing[UnsupportedOperationException] 
  }
}

object Helper {
  implicit class Failing[A](val f: Future[A]) extends Assertions with AsyncAssertions {
    def failing[T <: Throwable](implicit m: Manifest[T]) = {
      val w = new Waiter
      f onComplete {
        case Failure(e) => w(throw e); w.dismiss()
        case Success(_) => w.dismiss()
      }
      intercept[T] {
        w.await
      }
    } 
  } 
}

或者，如果您有多个 Future 并且您希望第一个不合格的 Future 通过测试:

Or, if you have multiple futures and you want the first non-conforming future to fail the test:

trait FailHelper extends Assertions with AsyncAssertions with PatienceConfiguration {
  def failingWith[T <: Throwable : Manifest](fs: Future[_]*)(implicit p: PatienceConfig) {
    val count = new java.util.concurrent.atomic.AtomicInteger(fs.size)
    val w = new Waiter
    for (f <- fs) f onComplete {
      case Success(i) =>
        w(intercept[T](i))
        println(s"Bad success $i")
        w.dismiss()
      case Failure(e: T) =>
        println(s"Failed $e OK, count ${count.get}")
        w(intercept[T](throw e))
        if (count.decrementAndGet == 0) w.dismiss()
      case Failure(e) =>
        println(s"Failed $e Bad")
        w(intercept[T](throw e))
        w.dismiss()
    }
    w.await()(p)
  }
}

使用情况

class Test extends FlatSpec with Matchers with ScalaFutures with ParallelTestExecution with FailHelper {
  it should "throw for invalid Ids" in {
    val sut = new Goof()
    import sut._

    val patienceConfig = null  // shadow the implicit
    implicit val p = PatienceConfig(timeout = 10 seconds)

    // all should fail this way
    //failingWith[UnsupportedOperationException](goof(), goofy(3), foog(5))
    //failingWith[UnsupportedOperationException](goof(), foog(5))
    failingWith[UnsupportedOperationException](goof(), goof(2), goof(3))
  }
}

受到这个不受欢迎的答案的启发.

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