Simple Unit Test

// Simple Unit Test w/o Futures
// For testing Future[+T], please see https://pastebin.com/eHqiDQWf

// SimpleService.scala:
class SimpleService {
  def getAverage(lst: Traversable[Int]): Int = {
    lst.sum / lst.size
  }
}

// SimpleServiceSpec.scala:
import org.scalatest.mockito.MockitoSugar
import org.scalatestplus.play.PlaySpec
import services.SimpleService

class SimpleServiceSpec extends PlaySpec with MockitoSugar {
  val service = new SimpleService

  "A SimpleService" when {
    "average is processed for 123456" should {
      "return 3" in {
        service.getAverage(List(1, 2, 3, 4, 5, 6)) mustBe 3
      }
    }
    "average is processed for empty list" should {
      "throw Exception" in {
        an [ArithmeticException] mustBe thrownBy (service.getAverage(Nil))
      }
    }
  }
}

// Output:
SimpleServiceSpec:
A SimpleService
  when average is processed for 123456
  - should return 3.5
  when average is processed for empty list
  - should throw Exception
ScalaTest
Run completed in 1 second, 144 milliseconds.
Total number of tests run: 2
Suites: completed 1, aborted 0
Tests: succeeded 2, failed 0, canceled 0, ignored 0, pending 0
All tests passed.