Testing a Scala Aplication with ScalaTest - scala

Question

I have been going through documentations on ScalaTest but able to figure out what type of approach i should take for testing the app.
Code is divided amoung controller and service.
eg. Controller Code example
#Singleton
class Controller1 #Inject()(service1: ServiceClass1, authAction : AuthAction)
extends InjectedController {
//returns a list[]
def getSomeValue() = authAction {
val res = service1.getValue1()
val json = Json.toJson(res)
Ok(json)
}
}
Service Code Example -:
def getValue1() = {
implicit val graph = db.g
val infos = graph.V.hasLabel[someModel].toList()
infos.map(vertex => {
val someModel = vertex.toCC[someModel]
val item = info(someId =
someModel.someId.getOrElse("").toString,
category = SomeModel.category,
description = someModel.description)
item
})
}
I am very new to Testing and Scala both, I also understand the code but not able to understand where to begin.
This is just a sample code which is very similar.

Answer 1

It seems like what you're looking for is a way to mock service1.getValue1() in your Controller1.
Scalatest supports a couple different ways to do this: http://www.scalatest.org/user_guide/testing_with_mock_objects
In your case, to test def getSomeValue(); you'd need to define a mock and set the right expectations so that when called from the test, the mock returns the expected responses.
If you'd like to use scala mock, you'd need to add it as a dependency in your sbt build config. You can do that by adding this dependency to your tests:
"org.scalamock" %% "scalamock" % "4.4.0" % Test
And then, your test could be something like this:
import org.scalamock.scalatest.MockFactory
import org.scalatest.flatspec.AnyFlatSpec
import org.scalatest.matchers.should.Matchers
class Controller1Spec extends AnyFlatSpec with Matchers with MockFactory {
"Controller1" should "respond with a valid response" in {
val mockService = mock[ServiceClass1]
(mockService.getValue1 _).when().returning("Some Response").once()
val mockAuthAction = mock[AuthAction] //assuming you've got an action called AuthAction
//you'd need to mock this one too, in order for it to work
(mockAuthAction.invokeBlock _) expects(_) onCall((r,b) => b(r))
new Controller1(mockService, mockAuthAction) shouldBe Ok("Some Response")
}
}
There's a number of posts on mocking for Scala which you should be able to find, like this one here: https://scalamock.org/user-guide/advanced_topics/