One dimensional game of life

gistfile1.scala

import org.junit.runner.RunWith
import org.scalatest.junit.JUnitRunner
import org.scalatest.FunSuite

@RunWith(classOf[JUnitRunner])
class GameOfLifeTest extends FunSuite {

  type Rules = ((Int, Int, Int)) => Int

  case class TheRules(rules: List[Int]) extends Rules {
    def apply(tuple: (Int, Int, Int)) = {
      val (a, b, c) = tuple
      val index = c + b * 2 + a * 4
      rules(index)
    }
  }

  case class GameOfLife(state: List[Int]) {
    def step(implicit rules: Rules) = {
      val tuplesList = (state.reverse.head :: state ::: state.head :: Nil).sliding(3)
      GameOfLife((for (list <- tuplesList) yield
        list match {
          case a :: b :: c :: Nil => rules((a, b, c))
        }).toList)
    }
  }

  test("(0,1,0) becomes (0,0,1) after one step") {
    implicit val rules = TheRules(List(0, 0, 0, 1, 1, 0, 0, 0))
    val game = GameOfLife(List(0, 1, 0))
    val next = game.step
    assert(next == GameOfLife(List(0, 0, 1)))
  }

  test("(0,1,1) becomes (0,1,0) after one step") {
    implicit val rules = TheRules(List(0, 0, 0, 1, 1, 0, 0, 0))
    val game = GameOfLife(List(0, 1, 1))
    val next = game.step
    assert(next == GameOfLife(List(0, 1, 0)))
  }
}