Mastermind.scala

package eu.bjean

object Mastermind {
  def check(secret: Symbol*)(guess: Symbol*): (Int, Int) = {

    val (goodPairs,badPairs) = secret.zip(guess).partition({ case (x, y) => x == y })    
    
    var badCount = 0
    
    if (badPairs.size > 0) {
      val (badSecret, badGuess) = badPairs.unzip
      val badSecSort = badSecret.sortBy(_.toString)
      val badGueSort = badGuess.sortBy(_.toString)
      badCount = badSecSort.zip(badGueSort).filter { case (x, y) => x == y }.size         
    }
    
    val pairs = goodPairs.size
    (pairs, badCount)

  }
}

MastermindSpec.scala

package eu.bjean

import org.junit.runner.RunWith
import org.scalatest.junit.JUnitRunner
import org.scalatest.FlatSpec
import org.scalatest.matchers.ShouldMatchers

@RunWith(classOf[JUnitRunner])
class MastermindSpec extends FlatSpec with ShouldMatchers {
  behavior of "Mastermind"    
  
  it should "find no good and no misplaced for a wrong guess" in {
    Mastermind.check (secret='blue)(guess='red) should equal (0,0)
  } 
  
  it should "find all good if guess equals secret" in {
    Mastermind.check (secret='blue)(guess='blue) should equal (1,0)
  }
  
  it should "find 1 good in a secret of 2" in {
    Mastermind.check ('red,'blue)('green,'blue) should equal (1,0)
  }
  
  it should "find 2 good in a secret of 3" in {
    Mastermind.check ('red,'blue,'red)('green,'blue,'red) should equal (2,0)
  }
  
  it should "find one misplaced in a secret of 2" in {
    Mastermind.check ('blue,'red)('green,'blue) should equal (0,1)
  }
  
  it should "find 2 misplaced in a secret of 3" in {
    Mastermind.check ('blue,'red,'green)('green,'blue,'yellow) should equal (0,2)
  }
  
  it should "find 1 wellplaced and 1 misplaced in a secret of 3" in {
    Mastermind.check ('blue,'blue,'green)('red,'blue,'blue) should equal (1,1)
  }
  
  it should "find 2 misplaced in a secret of with a specific order 3" in {
    Mastermind.check ('blue,'blue,'green)('green,'yellow,'blue) should equal (0,2)  
  }
  
  it should "find 2 misplaced in a secret of with a specific order 4" in {
    Mastermind.check ('green,'blue,'yellow,'red)('green,'yellow,'blue,'blue) should equal (1,2)
  }
}