scala - Specs2: how to test a class with more than one injected dependency?

Question

Play 2.4 app, using dependency injection for service classes.

I found that Specs2 chokes when a service class being tested has more than one injected dependency. It fails with "Can't find a constructor for class ..."

$ test-only services.ReportServiceSpec
[error] Can't find a constructor for class services.ReportService
[error] Error: Total 1, Failed 0, Errors 1, Passed 0
[error] Error during tests:
[error]         services.ReportServiceSpec
[error] (test:testOnly) sbt.TestsFailedException: Tests unsuccessful
[error] Total time: 2 s, completed Dec 8, 2015 5:24:34 PM

Production code, stripped to bare minimum to reproduce this problem:

package services

import javax.inject.Inject

class ReportService @Inject()(userService: UserService, supportService: SupportService) {  
   // ...  
}

class UserService {  
   // ...  
}

class SupportService {  
   // ...  
}

Test code:

package services

import javax.inject.Inject

import org.specs2.mutable.Specification

class ReportServiceSpec @Inject()(service: ReportService) extends Specification {

  "ReportService" should {
    "Work" in {
      1 mustEqual 1
    }
  }

}

If I remove either UserService or SupportService dependency from ReportService, the test works. But obviously the dependencies are in the production code for a reason. Question is, how do I make this test work?

Edit: When trying to run the test inside IntelliJ IDEA, the same thing fails, but with different messages: "Test framework quit unexpectedly", "This looks like a specs2 exception..."; see full output with stacktrace. I opened a Specs2 issue as instructed in the output, though I have no idea if the problem is in Play or Specs2 or somewhere else.

My library dependencies below. (I tried specifying Specs2 version explicitly, but that didn't help. Looks like I need specs2 % Test as is, for Play's test classes like WithApplication to work.)

resolvers += "scalaz-bintray" at "https://dl.bintray.com/scalaz/releases"
libraryDependencies ++= Seq(
  specs2 % Test,
  jdbc,
  evolutions,
  filters,
  "com.typesafe.play" %% "anorm" % "2.4.0",
  "org.postgresql" % "postgresql" % "9.4-1205-jdbc42"
)

Answer 1

There is limited support for dependency injection in specs2, mostly for execution environments or command-line arguments.

There is nothing preventing you from just using a lazy val and your favourite injection framework:

class MySpec extends Specification with Inject {
  lazy val reportService = inject[ReportService]

  ...
}

With Play and Guice, you could have a test helper such as this:

import play.api.inject.guice.GuiceApplicationBuilder
import scala.reflect.ClassTag    

trait Inject {
  lazy val injector = (new GuiceApplicationBuilder).injector()

  def inject[T : ClassTag]: T = injector.instanceOf[T]
}