OAuth2Test.scala

// it's good style to mark such objects/classes with sealed to guide complier 
// so it will check if match is exhaustive (all possible cases covered)
sealed abstract class Response
sealed abstract class Reason
abstract class TokenType

case class Token(t: TokenType) extends Response
case class Problem(reason: Reason) extends Response

case object InvalidResponse extends Reason
case object Connection extends Reason

// note that order of this classes in mattern matching matters
class OneTime extends TokenType
class Refreshable extends OneTime {
  def refresh() = ???
}

/*
foo match {
  case Token(t: Refreshable) => do something with t
  case Problem(reason) => reason match {
    case InvalidResponse => ...
    case ConnectionFailure => ...
  }
  _ => // just an example: Token(OneTime) will go there
}
*/