ScalaComponents

ScalaComponentsUseExtends.scala

package demos

import org.specs2.mutable._

class ScalaComponentsUseExtends extends Specification {

  trait DbComp {
    class Db {
      def name = "prod-db"
    }
    lazy val db = new Db
  }
  //////////
  trait CollectionComp extends DbComp {
    class Collection {
      def name = s"collection in ${db.name}"
    }
    lazy val collection = new Collection
  }
  //////////
  trait Collection2Comp extends DbComp {
    class Collection2 {
      def name = s"collection2 in ${db.name}"
    }
    lazy val collection2 = new Collection2
  }
  //////////
  trait ServiceComp extends CollectionComp {
    class Service {
      def name = s"service of ${collection.name}"
    }
    lazy val service = new Service
  }
  //////////
  trait Service2Comp extends Collection2Comp {
    class Service2 {
      def name = s"service2 of ${collection2.name}"
    }
    lazy val service2 = new Service2
  }
  //////////
  trait ControllerComp extends ServiceComp with Service2Comp {
    class Controller {
      def name = s"controller with ${service.name} and ${service2.name}"
    }
    lazy val controller = new Controller
  }
  //////////

  "DI" should {
    "autowire" in {
      object Assembly extends ControllerComp
      Assembly.controller.name mustEqual("controller with service of collection in prod-db and service2 of collection2 in prod-db")
    }

    "autowire root level changes" in {
      object Assembly extends ControllerComp {
        override lazy val db = new Db {
          override def name = "stub-db"
        }
      }
      Assembly.controller.name mustEqual("controller with service of collection in stub-db and service2 of collection2 in stub-db")
    }
  }
}

ScalaComponentsUseSelfType.scala

package demos

import org.specs2.mutable._

class ScalaComponentsUseSelfType extends Specification {

  trait DbComp {
    class Db {
      def name = "prod-db"
    }
    lazy val db = new Db
  }
  //////////
  trait CollectionComp {self: DbComp =>
    class Collection {
      def name = s"collection in ${db.name}"
    }
    lazy val collection = new Collection
  }
  //////////
  trait Collection2Comp {self: DbComp =>
    class Collection2 {
      def name = s"collection2 in ${db.name}"
    }
    lazy val collection2 = new Collection2
  }
  //////////
  trait ServiceComp {self: CollectionComp =>
    class Service {
      def name = s"service of ${collection.name}"
    }
    lazy val service = new Service
  }
  //////////
  trait Service2Comp {self: Collection2Comp =>
    class Service2 {
      def name = s"service2 of ${collection2.name}"
    }
    lazy val service2 = new Service2
  }
  //////////
  trait ControllerComp {self: ServiceComp with Service2Comp =>
    class Controller {
      def name = s"controller with ${service.name} and ${service2.name}"
    }
    lazy val controller = new Controller
  }
  //////////
  trait Assembly extends ControllerComp with ServiceComp with Service2Comp with CollectionComp with Collection2Comp with DbComp

  "DI" should {
    "autowire" in {
      object Assembly extends Assembly
      Assembly.controller.name mustEqual("controller with service of collection in prod-db and service2 of collection2 in prod-db")
    }

    "autowire root level changes" in {
      object Assembly extends Assembly {
        override lazy val db = new Db {
          override def name = "stub-db"
        }
      }
      Assembly.controller.name mustEqual("controller with service of collection in stub-db and service2 of collection2 in stub-db")
    }
  }
}