Scala - Play - How to mock import play.api.libs.concurrent.CustomExecutionContext in Test and use it as an implicit param?

Question

I have a test which is testing a class that expects an implicit CustomExecutionContext:

@Singleton
class MyRepo @Inject()
(appConfigService: AppConfigService)
(implicit ec: RepositoryDispatcherContext)

Now I need to test this class and inject a mock dispatcher context during test. Initially I was thinking of using the standard global execution context that ships out of the box.

implicit executionContext = scala.concurrent.ExecutionContext.Implicits.global

But the test fails at it expects another type of instance:

could not find implicit value for parameter ec: common.executor.RepositoryDispatcherContext

This is mine Custom execution context:

import javax.inject.{Inject}
import akka.actor.ActorSystem
import play.api.libs.concurrent.CustomExecutionContext

class RepositoryDispatcherContext @Inject()(actorSystem: ActorSystem) extends CustomExecutionContext(actorSystem, "repository.dispatcher")

Was wondering how to inject a mock instance of my custom execution context to be used as an implicit param in my Test class?

Answer 1

You can create a sub class of your custom dispatcher and override the necessary methods:

import org.specs2.mutable.Specification

import akka.actor.ActorSystem
import scala.concurrent.ExecutionContext

class MySomethingSpec extends Specification with Mockito {

  "MySomething" should {    

    "mock repository dispatcher itself" in {
      class MyMockedRepositoryDispatcher(executionContext: ExecutionContext) extends RepositoryDispatcherContext(ActorSystem()) {
        override def execute(command: Runnable) = executionContext.execute(command)
        override def reportFailure(cause: Throwable) = executionContext.reportFailure(cause)
      }

      val executionContext: ExecutionContext = ??? // whatever you need
      val repositoryDispatcher: RepositoryDispatcherContext = new MyMockedRepositoryDispatcher(executionContext)

      // do what you need
      // assertions
    }
  }
}