build.sbt

libraryDependencies += "com.typesafe" % "config" % "1.2.1"

libraryDependencies += "org.scalacheck" %% "scalacheck" % "1.11.6" 

scalaVersion := "2.11.2"

Test.scala

import com.typesafe.config.ConfigFactory
import java.util.concurrent.TimeUnit
import org.scalacheck._
import scala.concurrent.duration.Duration

object nano extends Test(TimeUnit.NANOSECONDS, 0)
object micro extends Test(TimeUnit.MICROSECONDS, 1)
object millis extends Test(TimeUnit.MILLISECONDS, 2)
object seconds extends Test(TimeUnit.SECONDS, 3)
object minutes extends Test(TimeUnit.MINUTES, 4)
object hours extends Test(TimeUnit.HOURS, 5)
object days extends Test(TimeUnit.DAYS, 6)

abstract class Test(val unit: TimeUnit, n: Int) extends Properties(unit.toString){

  implicit final def durationArbitrary: Arbitrary[Duration] = {
    val x = math.pow(1000, n).toLong
    val z = 1000000L
    Arbitrary(
      Gen.choose[Long](
        (Int.MinValue.toLong * z) / x,
        (Int.MaxValue.toLong * z) / x
      ).map(Duration(_, unit))
    )
  }

  property("test") = Prop.forAll{ a: Duration =>
    val key = "a"
    val str = key + " : " + a.toString
    val d = ConfigFactory.parseString(str).getDuration(key, unit)
    val x = Duration(d, unit)
    if(x != a){
      println((d, x, a))
    }
    a == x
  }

}