P01 (*) Find the last element of a list.

P01.scala

package com.learner.s99

/*
(*) Find the last element of a list.
Example:
scala> last(List(1, 1, 2, 3, 5, 8))
res0: Int = 8
 */

object P01 {
  def last(input: List[Any]): Any = last(input, None)

  private def last(input: List[Any], lastElement: Any): Any = input match {
    case List() => lastElement
    case head :: tail => last(tail, head)
  }
}

P01Spec.scala

package com.learner.s99

import com.learner.s99.P01.last
import org.scalatest.{FlatSpec, MustMatchers}

class P01Spec extends FlatSpec
with MustMatchers {

  behavior of "A List"
  it must "return 8 in List(1,2,3,4,5,6,7,8) as last element" in {
    last(List(1, 2, 3, 4, 5, 6, 7, 8)) must equal(8)
  }

  it must "return 1 in List(1) as last element" in {
    last(List(1)) must equal(1)
  }

  it must "return 'gamma' in List(alpha, beta, gamma) as last element" in {
    last(List("alpha","beta", "gamma")) must equal("gamma")
  }

  it must "return 'two' in List(1, two) as last element" in {
    last(List(1, "two")) must equal("two")
  }

  it must "return None empty List as last element" in {
    last(List()) must be(None)
  }
}