How to combine functionalities?

gistfile1.scala

A:

trait DoValidator {
  def validate(input:String): Validation = ...
}

trait Doer extends DoValidator {
   def do(input: String) = validate(input) match 
      case Success => ....
      case Failuer => ....
}

with tests like:

trait AlwaysFailValidation extends DoerValidator {
   def validate(input:String) = Failuer()
}

test("that will handle failuers") {
   // given
   val doer: Doer with AlwaysFailValidation() {}
   // when
   doer.do("some input")
   // then
    ....
}

OR


B:

trait Doer {
   def do(input: String)(validate: String=>Validation) = validate(input) match 
      case Success => ....
      case Failuer => ....
}

with tests like:

test("that will handle failuers") {
   // when
   doer.do("some input")(v => Failuer)
   // then
    ....
}