how to mock external WS API calls in Scala Play framework - scala

Question

I have an existing Scala play application which has a REST API that calls another external REST API. I want to mock the external Web service returning fake JSON data for internal tests. Based on example from: https://www.playframework.com/documentation/2.6.x/ScalaTestingWebServiceClients
I followed example exactly as in Documentation and I'm getting compiler errors due to deprecated class Action.
import play.core.server.Server
import play.api.routing.sird._
import play.api.mvc._
import play.api.libs.json._
import play.api.test._
import scala.concurrent.Await
import scala.concurrent.duration._
import org.specs2.mutable.Specification
import product.services.market.common.GitHubClient
class GitHubClientSpec extends Specification {
import scala.concurrent.ExecutionContext.Implicits.global
"GitHubClient" should {
"get all repositories" in {
Server.withRouter() {
case GET(p"/repositories") => Action {
Results.Ok(Json.arr(Json.obj("full_name" -> "octocat/Hello-World")))
}
} { implicit port =>
WsTestClient.withClient { client =>
val result = Await.result(
new GitHubClient(client, "").repositories(), 10.seconds)
result must_== Seq("octocat/Hello-World")
}
}
}
}
}
object Action in package mvc is deprecated: Inject an ActionBuilder
(e.g. DefaultActionBuilder) or extend
BaseController/AbstractController/InjectedController
And this is the primary example from latest official docs which in fact contains a compile time error, given this example doesn't work how should be the proper way to easily mock an external API using Scala Play?

Answer 1

You may change your example to:
Server.withRouterFromComponents() { cs => {
case GET(p"/repositories") => cs.defaultActionBuilder {
Results.Ok(Json.arr(Json.obj("full_name" -> "octocat/Hello-World")))
}
}
} { implicit port =>
WsTestClient.withClient { client =>
val result = Await.result(
new GitHubClient(client, "").repositories(), 10.seconds)
result should be(Seq("octocat/Hello-World"))
}
}
To be honest, I'm not 100% sure if this is the nicest way. However I have submitted a PR to the play framework so you might watch that space for comments from the makers.

Answer 2

If you're using standalone version of play-ws you can use this library https://github.com/f100ded/play-fake-ws-standalone like this
import akka.actor.ActorSystem
import akka.stream.ActorMaterializer
import org.f100ded.play.fakews._
import org.scalatest._
import play.api.libs.ws.JsonBodyWritables._
import scala.concurrent.duration.Duration
import scala.concurrent._
import scala.language.reflectiveCalls
/**
* Tests MyApi HTTP client implementation
*/
class MyApiClientSpec extends AsyncFlatSpec with BeforeAndAfterAll with Matchers {
implicit val system = ActorSystem()
implicit val materializer = ActorMaterializer()
import system.dispatcher
behavior of "MyApiClient"
it should "put access token to Authorization header" in {
val accessToken = "fake_access_token"
val ws = StandaloneFakeWSClient {
case request # GET(url"http://host/v1/foo/$id") =>
// this is here just to demonstrate how you can use URL extractor
id shouldBe "1"
// verify access token
request.headers should contain ("Authorization" -> Seq(s"Bearer $accessToken"))
Ok(FakeAnswers.foo)
}
val api = new MyApiClient(ws, baseUrl = "http://host/", accessToken = accessToken)
api.getFoo(1).map(_ => succeed)
}
// ... more tests
override def afterAll(): Unit = {
Await.result(system.terminate(), Duration.Inf)
}
}