如何测试客户端 Akka HTTP

Question

我刚刚开始测试Akka HTTP Request-Level Client-Side API (Future-Based)。我一直在努力弄清楚的一件事是如何为此编写单元测试。有没有办法模拟响应并完成未来而无需实际执行 HTTP 请求？

我正在查看 API 和 testkit 包，试图了解如何使用它，结果却在文档中找到它实际上说的：

akka-http-testkit 用于验证服务器端服务实现的测试工具和实用程序集

我在想 TestServer（有点像 Akka Streams 的 TestSource）并使用服务器端路由 DSL 创建预期的响应，并以某种方式将其连接到 Http 对象。

这是我要测试的函数的简化示例：

object S3Bucket {

  def sampleTextFile(uri: Uri)(
    implicit akkaSystem: ActorSystem,
    akkaMaterializer: ActorMaterializer
  ): Future[String] = {
    val request = Http().singleRequest(HttpRequest(uri = uri))
    request.map { response => Unmarshal(response.entity).to[String] }
  }
}

Answer 1

我认为总的来说，您已经意识到最好的方法是模拟响应。在 Scala 中，这可以使用 Scala Mock http://scalamock.org/

来完成

如果您安排您的代码，以便将您的 akka.http.scaladsl.HttpExt 实例依赖注入到使用它的代码中（例如，作为构造函数参数），那么在测试期间您可以注入 mock[HttpExt] 的实例而不是使用构建的实例Http 应用方法。

编辑：我猜这是因为不够具体而被否决。这是我将如何构建您的场景的模拟。所有的隐含使它变得更加复杂。

main中的代码：

import akka.actor.ActorSystem
import akka.http.scaladsl.Http
import akka.http.scaladsl.model.{Uri, HttpResponse, HttpRequest}
import akka.http.scaladsl.unmarshalling.Unmarshal
import akka.stream.ActorMaterializer

import scala.concurrent.{ExecutionContext, Future}

trait S3BucketTrait {

  type HttpResponder = HttpRequest => Future[HttpResponse]

  def responder: HttpResponder

  implicit def actorSystem: ActorSystem

  implicit def actorMaterializer: ActorMaterializer

  implicit def ec: ExecutionContext

  def sampleTextFile(uri: Uri): Future[String] = {

    val responseF = responder(HttpRequest(uri = uri))
    responseF.flatMap { response => Unmarshal(response.entity).to[String] }
  }
}

class S3Bucket(implicit val actorSystem: ActorSystem, val actorMaterializer: ActorMaterializer) extends S3BucketTrait {

  override val ec: ExecutionContext = actorSystem.dispatcher

  override def responder = Http().singleRequest(_)
}

test中的代码：

import akka.actor.ActorSystem
import akka.http.scaladsl.model._
import akka.stream.ActorMaterializer
import akka.testkit.TestKit
import org.scalatest.{BeforeAndAfterAll, WordSpecLike, Matchers}
import org.scalamock.scalatest.MockFactory
import scala.concurrent._
import scala.concurrent.duration._
import scala.concurrent.Future

class S3BucketSpec extends TestKit(ActorSystem("S3BucketSpec"))
with WordSpecLike with Matchers with MockFactory with BeforeAndAfterAll  {


  class MockS3Bucket(reqRespPairs: Seq[(Uri, String)]) extends S3BucketTrait{

    override implicit val actorSystem = system

    override implicit val ec = actorSystem.dispatcher

    override implicit val actorMaterializer = ActorMaterializer()(system)

    val mock = mockFunction[HttpRequest, Future[HttpResponse]]

    override val responder: HttpResponder = mock

    reqRespPairs.foreach{
      case (uri, respString) =>
        val req = HttpRequest(HttpMethods.GET, uri)
        val resp = HttpResponse(status = StatusCodes.OK, entity = respString)
        mock.expects(req).returning(Future.successful(resp))
    }
  }

  "S3Bucket" should {

    "Marshall responses to Strings" in {
      val mock = new MockS3Bucket(Seq((Uri("http://example.com/1"), "Response 1"), (Uri("http://example.com/2"), "Response 2")))
      Await.result(mock.sampleTextFile("http://example.com/1"), 1 second) should be ("Response 1")
      Await.result(mock.sampleTextFile("http://example.com/2"), 1 second) should be ("Response 2")
    }
  }

  override def afterAll(): Unit = {
    val termination = system.terminate()
    Await.ready(termination, Duration.Inf)
  }
}

build.sbt 依赖：

libraryDependencies += "com.typesafe.akka" % "akka-http-experimental_2.11" % "2.0.1"

libraryDependencies += "org.scalamock" %% "scalamock-scalatest-support" % "3.2" % "test"

libraryDependencies += "org.scalatest" % "scalatest_2.11" % "2.2.6"

libraryDependencies += "com.typesafe.akka" % "akka-testkit_2.11" % "2.4.1"

Answer 2

考虑到您确实想为您的 HTTP 客户端编写单元测试，您应该假装没有真正的服务器并且不跨越网络边界，否则您显然会进行集成测试。在像您这样的情况下强制执行可单元测试分离的一个众所周知的方法是拆分接口和实现。只需定义一个抽象访问外部 HTTP 服务器的接口及其真实和虚假的实现，如下图所示

import akka.actor.Actor
import akka.pattern.pipe
import akka.http.scaladsl.HttpExt
import akka.http.scaladsl.model.{HttpRequest, HttpResponse, StatusCodes}
import scala.concurrent.Future

trait HTTPServer {
  def sendRequest: Future[HttpResponse]
}

class FakeServer extends HTTPServer {
  override def sendRequest: Future[HttpResponse] =
    Future.successful(HttpResponse(StatusCodes.OK))
}

class RealServer extends HTTPServer {

  def http: HttpExt = ??? //can be passed as a constructor parameter for example

  override def sendRequest: Future[HttpResponse] =
    http.singleRequest(HttpRequest(???))
}

class HTTPClientActor(httpServer: HTTPServer) extends Actor {

  override def preStart(): Unit = {
    import context.dispatcher
    httpServer.sendRequest pipeTo self
  }

  override def receive: Receive = ???
}

并结合FakeServer 测试您的HTTPClientActor。

Answer 3

我希望有一种方法可以利用某种测试参与者系统，但在没有这种方法（或其他惯用方式）的情况下，我可能会做这样的事情：

object S3Bucket {

  type HttpResponder = HttpRequest => Future[HttpResponse]

  def defaultResponder = Http().singleRequest(_)

  def sampleTextFile(uri: Uri)(
    implicit akkaSystem: ActorSystem,
    akkaMaterializer: ActorMaterializer,
    responder: HttpResponder = defaultResponder
  ): Future[String] = {
    val request = responder(HttpRequest(uri = uri))
    request.map { response => Unmarshal(response.entity).to[String] }
  }
}

然后在我的测试中，我可以提供一个模拟 HttpResponder。