using scala trait and object for DI

native_di.scala

// https://www.michaelpollmeier.com/2014/06/29/simple-dependency-injection-scala

// define
trait MyService {
  def foo = 42
}

// instantiate
object MyService extends MyService


// inject
class MyClient {
  val service: MyService = MyService
}

// dual implementation
trait MyOtherService extends MyService {...}
object MyOtherService extends MyOtherService
val client = new MyClient { override val service = MyOtherService }


// test
val mockService = mock[MyService]
val testClient = new MyClient { override val service = mockService }