Stackable Trait simulate

Simulate.scala

trait BeforeAndAfterEach { def beforeEach(): Unit = () }
trait ResetSystemProperties extends BeforeAndAfterEach { override def beforeEach(): Unit = println("reset") }
class A extends BeforeAndAfterEach with ResetSystemProperties { override def beforeEach() { println("test") } }
class B extends BeforeAndAfterEach with ResetSystemProperties { override def beforeEach() { super.beforeEach(); println("test") } }

scala> (new A()).beforeEach
test

scala> (new B()).beforeEach
reset
test