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
}
}
}
}
除了我无法使这段代码工作之外,我想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?
答案 0 :(得分:18)
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
答案 1 :(得分:13)
我花了一段时间才发现这个想法,我想分享一下。我应该阅读发行说明。在specs2 v3.5中,需要使用隐式ExecutionEnv来为将来使用await。这也可以用于将来的转换(即地图),请参阅http://notes.implicit.ly/post/116619383574/specs2-3-5。
从那里摘录以供快速参考:
import org.specs2.concurrent.ExecutionEnv
class MySpec extends mutable.Specification {
"test of a Scala Future" >> { implicit ee: ExecutionEnv =>
Future(1) must be_>(0).await
}
}
答案 2 :(得分:6)
在specs2中有一个很好的东西 - await
的隐式Future[Result]
方法。如果您利用未来的转换,您可以这样写:
"save notification" in {
notificationDao.saveNotification(notification) map { writeResult =>
writeResult.ok must be equalTo (true)
} await
}
当需要一些具有异步功能的数据安排时,未来的构成将得到拯救:
"get user notifications" in {
{
for {
_ <- notificationDao.saveNotifications(user1Notifications)
_ <- notificationDao.saveNotifications(user2Notifications)
foundUser1Notifications <- notificationDao.getNotifications(user1)
} yield {
foundUser1Notifications must be equalTo (user1Notifications)
}
} await
}
请注意我们必须使用额外的块来进行理解才能说服编译器。我认为这很吵,所以如果我们在函数中转换await
方法,我们会得到一个更好的语法:
def awaiting[T]: Future[MatchResult[T]] => Result = { _.await }
"get user notifications" in awaiting {
for {
_ <- notificationDao.saveNotifications(user1Notifications)
_ <- notificationDao.saveNotifications(user2Notifications)
foundUser1Notifications <- notificationDao.getNotifications(user1)
} yield {
foundUser1Notifications must be equalTo (user1Notifications)
}
}
答案 3 :(得分:3)
onComplete
返回Unit
,以便代码块立即返回,测试结束后才能执行任何操作。为了正确测试Future
的结果,您需要阻塞直到它完成。您可以使用Await
并设置最长Duration
等待。
import scala.concurrent._
import scala.concurrent.duration._
Await.result(testImage, Duration("10 seconds")) must not have length(0)
答案 4 :(得分:3)
想知道为什么@etorreborre没有提到“最终”
class EventuallyMatchersSpec extends Specification with FutureMatchers with ExpectationsDescription { section("travis")
addParagraph { """
`eventually` can be used to retry any matcher until a maximum number of times is reached
or until it succeeds.
""" }
"A matcher can match right away with eventually" in {
1 must eventually(be_==(1))
}
"A matcher can match right away with eventually, even if negated" in {
"1" must not (beNull.eventually)
}
"A matcher will be retried automatically until it matches" in {
val iterator = List(1, 2, 3).iterator
iterator.next must be_==(3).eventually
}
"A matcher can work with eventually and be_== but a type annotation is necessary or a be_=== matcher" in {
val option: Option[Int] = Some(3)
option must be_==(Some(3)).eventually
}
答案 5 :(得分:0)
等待是一种反模式。永远不要使用它。
您可以使用ScalaFutures
,IntegrationPatience
和Eventually
之类的特征。
示例:
import org.specs2.mutable.Specification
import scala.concurrent.ExecutionContext.Implicits.global
import scala.util.{Failure, Success}
import org.scalatest.concurrent.{IntegrationPatience, ScalaFutures}
import scala.concurrent.Future
class AsyncWebClientSpec extends Specification with ScalaFutures
with IntegrationPatience{
"WebClient when downloading images" should {
"for a valid link return non-zero content " in {
whenReady(Future.successful("Done")){ testImage =>
testImage must be equalTo "Done"
// Do whatever you need
}
}
}
}