How to mock spray-client response - unit-testing

Question

I have a simple spray client :
val pipeline = sendReceive ~> unmarshal[GoogleApiResult[Elevation]]
val responseFuture = pipeline {Get("http://maps.googleapis.com/maps/api/elevation/jsonlocations=27.988056,86.925278&sensor=false") }
responseFuture onComplete {
case Success(GoogleApiResult(_, Elevation(_, elevation) :: _)) =>
log.info("The elevation of Mt. Everest is: {} m", elevation)
shutdown()
case Failure(error) =>
log.error(error, "Couldn't get elevation")
shutdown()
}
Full code can be found here.
I want to mock the response of the server to test the logic in the Success and Failure cases. The only relevant information i found was here but I haven't been able to use the cake pattern to mock the sendReceive method.
Any suggestion or example would be greatly appreciated.

Answer 1

Here's an example of one way to mock it using specs2 for the test spec and mockito for the mocking. First, the Main object refactored into a class setup for mocking:
class ElevationClient{
// we need an ActorSystem to host our application in
implicit val system = ActorSystem("simple-spray-client")
import system.dispatcher // execution context for futures below
val log = Logging(system, getClass)
log.info("Requesting the elevation of Mt. Everest from Googles Elevation API...")
import ElevationJsonProtocol._
import SprayJsonSupport._
def sendAndReceive = sendReceive
def elavation = {
val pipeline = sendAndReceive ~> unmarshal[GoogleApiResult[Elevation]]
pipeline {
Get("http://maps.googleapis.com/maps/api/elevation/json?locations=27.988056,86.925278&sensor=false")
}
}
def shutdown(): Unit = {
IO(Http).ask(Http.CloseAll)(1.second).await
system.shutdown()
}
}
Then, the test spec:
class ElevationClientSpec extends Specification with Mockito{
val mockResponse = mock[HttpResponse]
val mockStatus = mock[StatusCode]
mockResponse.status returns mockStatus
mockStatus.isSuccess returns true
val json = """
{
"results" : [
{
"elevation" : 8815.71582031250,
"location" : {
"lat" : 27.9880560,
"lng" : 86.92527800000001
},
"resolution" : 152.7032318115234
}
],
"status" : "OK"
}
"""
val body = HttpEntity(ContentType.`application/json`, json.getBytes())
mockResponse.entity returns body
val client = new ElevationClient{
override def sendAndReceive = {
(req:HttpRequest) => Promise.successful(mockResponse).future
}
}
"A request to get an elevation" should{
"return an elevation result" in {
val fut = client.elavation
val el = Await.result(fut, Duration(2, TimeUnit.SECONDS))
val expected = GoogleApiResult("OK",List(Elevation(Location(27.988056,86.925278),8815.7158203125)))
el mustEqual expected
}
}
}
So my approach here was to first define an overridable function in the ElevationClient called sendAndReceive that just delegates to the spray sendReceive function. Then, in the test spec, I override that sendAndReceive function to return a function that returns a completed Future wrapping a mock HttpResponse. This is one approach for doing what you want to do. I hope this helps.

Answer 2

There's no need to introduce mocking in this case, as you can simply build a HttpResponse much more easily using the existing API:
val mockResponse = HttpResponse(StatusCodes.OK, HttpEntity(ContentTypes.`application/json`, json.getBytes))
(Sorry for posting this as another answer, but don't have enough karma to comment)