scala - 如何测试返回Future的方法？

我想测试一个返回Future的方法。我的尝试如下：

import  org.specs2.mutable.Specification
import scala.concurrent.ExecutionContext.Implicits.global
import scala.util.{Failure, Success}

class AsyncWebClientSpec extends Specification{

  "WebClient when downloading images" should {
    "for a valid link return non-zero content " in {
      val testImage = AsyncWebClient.get("https://www.google.cz/images/srpr/logo11ww.png")
      testImage.onComplete { res =>
        res match {
          case Success(image) => image must not have length(0)
          case _ =>
        }
        AsyncWebClient.shutDown
      }
    }
  }
}

除了我无法使该代码正常工作之外，我猜想还有一种更好的方法可以用面向Future的匹配器测试期货。

如何在specs2中正确执行操作？

最佳答案

您可以使用Matcher.await方法将Matcher[T]转换为Matcher[Future[T]]：

val testImage: Future[String] =
   AsyncWebClient.get("https://www.google.cz/images/srpr/logo11ww.png")

// you must specify size[String] here to help type inference
testImage must not have size[String](0).await

// you can also specify a number of retries and duration between retries
testImage must not have size[String](0).await(retries = 2, timeout = 2.seconds)

// you might also want to check exceptions in case of a failure
testImage must throwAn[Exception].await