Scala example source code file (LensTest.scala)

This example Scala source code file (LensTest.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.

Learn more about this Scala project at its project page.

Java - Scala tags/keywords

boolean, equal, int, lens, lenstest, numericlens, speclite, string

The LensTest.scala Scala example source code

package scalaz
package std

import std.AllInstances._
import scalaz.scalacheck.ScalazProperties._
import scalaz.scalacheck.ScalazArbitrary._
import org.scalacheck.{Gen, Arbitrary}
import Lens.{lens => _, _}
import org.scalacheck.Prop.forAll

object LensTest extends SpecLite {

  {
    implicit def lensArb = Arbitrary(Gen.const(Lens.lensId[Int]))
    implicit def lensEqual = new Equal[Lens[Int, Int]] {
      def equal(a1: Lens[Int, Int], a2: Lens[Int, Int]): Boolean = a1.get(0) == a2.get(0)
    }
    checkAll("Lens", category.laws[Lens]) // not really testing much!
  }

  checkAll("id", lens.laws(Lens.lensId[Int]))
  checkAll("trivial", lens.laws(Lens.trivialLens[Int]))
  checkAll("codiagLens", lens.laws(Lens.codiagLens[Int]))
  checkAll("Tuple2.first", lens.laws(Lens.firstLens[Int, Int]))
  checkAll("Tuple2.second", lens.laws(Lens.secondLens[Int, Int]))
  checkAll("Set.contains", lens.laws(Lens.lensId[Set[Int]].contains(0)))
  checkAll("Map.member", lens.laws(Lens.lensId[Map[Boolean, Int]].member(true)))
  checkAll("sum", lens.laws(Lens.firstLens[Int, String].sum(Lens.firstLens[Int, String])))

  "NumericLens" should {
    "+=" ! forAll((i: Int) => (Lens.lensId[Int] += i).run(1) must_=== ((i + 1) -> (i + 1)))
    "-=" ! forAll((i: Int) => (Lens.lensId[Int] -= i).run(1) must_=== ((1 - i) -> (1 - i)))
    "*=" ! forAll((i: Int) => (Lens.lensId[Int] *= i).run(2) must_=== ((i * 2) -> (i * 2)))
  }
}