Polymorphic matching

FruitTest.scala

class FruitTest extends SpecificationWithJUnit {
  trait Fruit

  case class Apple(color: String) extends Fruit

  case class Peach(ripeness: Double) extends Fruit

  def aColorfulApple(color: String): Matcher[Fruit] = {
    val appleMatcher: Matcher[Apple] = be_===(color) ^^ { a: Apple =>
      a.color aka "apple color"
    }
    val fruitMatcher: Matcher[Fruit] = (_: Fruit) match {
      case apple: Apple => appleMatcher.apply(MustExpectable[Apple](apple))
      case _ => ko("something which is not an apple")
    }
    fruitMatcher
  }

  "match an apple from a set of fruits" in {
    Set(Apple("red"), Apple("green"), Peach(0.3)) must contain(aColorfulApple("green"))
  }
}

yup, this really looks nice in tests