Scala example source code file (MapTest.scala)

This example Scala source code file (MapTest.scala) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Scala by Example" ^TM.

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Java - Scala tags/keywords

arbitrary, bkc, boolean, contravariant, equal, int, list, long, map, notnatural, string, xmaptest

The MapTest.scala Scala example source code

package scalaz
package std

import std.AllInstances._
import org.scalacheck.Arbitrary, Arbitrary.arbitrary
import scalaz.scalacheck.ScalazProperties._
import scala.collection.immutable.{Map => SMap, MapLike}
import scala.math.{Ordering => SOrdering}
import org.scalacheck.Prop.forAll

abstract class XMapTest[Map[K, V] <: SMap[K, V] with MapLike[K, V, Map[K, V]], BKC[_]]
  (dict: MapSubInstances with MapSubFunctions{
     type XMap[A, B] = Map[A, B]
     type BuildKeyConstraint[A] = BKC[A]
   })(implicit BKCF: Contravariant[BKC], OI: BKC[Int], OS: BKC[String]) extends SpecLite {
  import dict._

  checkAll(traverse.laws[Map[Int, ?]])
  checkAll(FoldableTests.anyAndAllLazy[Map[Int, ?]])
  checkAll(isEmpty.laws[Map[Int, ?]])
  checkAll(bind.laws[Map[Int, ?]])
  checkAll(align.laws[Map[Int, ?]])
  checkAll(monoid.laws[Map[Int,String]])
  checkAll(order.laws[Map[Int,String]])
  checkAll(equal.laws[Map[Int,String]])

  "satisfy equals laws when not natural" ! equal.laws[Map[NotNatural, String]]

  implicit def mapArb[A: Arbitrary: BKC, B: Arbitrary]: Arbitrary[Map[A, B]] =
    Arbitrary(arbitrary[SMap[A, B]] map (m => fromSeq(m.toSeq:_*)))

  class NotNatural(val id: Int)
  implicit def NotNaturalArbitrary: Arbitrary[NotNatural] =
    Arbitrary(arbitrary[Int] map (new NotNatural(_)))

  implicit def NotNaturalOrder: Order[NotNatural] =
    Order.orderBy[NotNatural, Int](_.id)

  implicit def NotNaturalBKC: BKC[NotNatural] = BKCF.contramap(OI)(_.id)

  implicit def NotNaturalEqual: Equal[NotNatural] = new Equal[NotNatural] {
    def equal(a1: NotNatural, a2: NotNatural): Boolean = a1.id == a2.id
  }

  "map ordering" ! forAll {
    val O = implicitly[Order[Map[String,Int]]]
    val O2 = SOrdering.Iterable(implicitly[SOrdering[(String,Int)]])
    (kvs: List[(String,Int)], kvs2: List[(String,Int)]) => {
      val (m1, m2) = (fromSeq(kvs:_*), fromSeq(kvs2:_*))
      ((m1.size == kvs.size) && (m2.size == kvs2.size)) ==> {
        val l: Boolean = O.lessThan(m1, m2)
        val r: Boolean = (if (m1.size < m2.size) true
                          else if (m1.size > m2.size) false
                          else O2.lt(kvs.sortBy(_._1), kvs2.sortBy(_._1)))
        l == r
      }
    }
  }

  "align" ! forAll { (a: Map[Int, String], b: Map[Int, Long]) =>
    import std.set._, \&/._
    val F = Align[Map[Int, ?]]
    val x = F.align(a, b)
    val keysA = a.keySet
    val keysB = b.keySet

    x must_=== F.alignWith[String, Long, String \&/ Long](identity)(a, b)
    ==>>.fromList(x.toList) must_=== Align[Int ==>> ?].align(==>>.fromList(a.toList), ==>>.fromList(b.toList))
    x.keySet must_=== (keysA ++ keysB)

    x.filter(_._2.isThis).keySet must_=== (keysA -- keysB)
    x.filter(_._2.isThat).keySet must_=== (keysB -- keysA)
    x.filter(_._2.isBoth).keySet must_=== (keysA & keysB)

    x.filter(_._2.isThis) must_=== F.map(a.filter{case (k, _) => ! keysB(k)})(This(_))
    x.filter(_._2.isThat) must_=== F.map(b.filter{case (k, _) => ! keysA(k)})(That(_))
  }

  "getOrAdd" ! forAll { (m0: Map[Int, Long], k: Int, vOld: Long, vNew: Long) =>
    import std.tuple._, std.anyVal._, std.map._

    val mWithout = m0 - k
    val mWithOld = m0 + (k -> vOld)
    val mWithNew = m0 + (k -> vNew)

    // not already in map
    getOrAdd[Id.Id, Int, Long](mWithout, k)(vNew) must_=== (mWithNew, vNew)

    // already in map
    getOrAdd[Id.Id, Int, Long](mWithOld, k)(vNew) must_=== (mWithOld, vOld)

    // lazy
    var evaluated = false
    getOrAdd[Id.Id, Int, Long](mWithOld, k)({evaluated = true; vNew}) must_=== (mWithOld, vOld)
    evaluated must_=== false
  }
}

private object DIContravariant extends Contravariant[λ[α => DummyImplicit]] {
  def contramap[A, B](fa: DummyImplicit)(f: B => A) = fa
}

object MapTest extends XMapTest[SMap, λ[α => DummyImplicit]](std.map)(DIContravariant, implicitly, implicitly)