ScalaCheck - Ordered array generator

I assume you want an arbitrary array of integers that's been sorted, right? If that's the case, you can use either of the following approaches to get a Gen[Array[Int]]:

val genIntArray = Gen.containerOf[Array, Int]( Gen.chooseNum(Int.MinValue, Int.MaxValue) ) 

Or:

val genIntArray = implicitly[Arbitrary[Array[Int]]].arbitrary 

You can then use map to modify the generator to sort its results:

 val genSortedIntArray = genIntArray.map(_.sorted) 

Now you can run genSortedIntArray.sample.get a few times to convince yourself that the result is a sorted array of random integers.

If you want an Arbitrary for sorted arrays of integers, it's best to define a wrapper instead of hiding the default Arbitrary[Array[Int]]. For example, you could write the following:

case class SortedIntArray(value: Array[Int]) extends AnyVal object SortedIntArray { implicit val arb: Arbitrary[SortedIntArray] = Arbitrary( genSortedIntArray.map(SortedIntArray(_)) ) } 

And then:

forAll { (a: SortedIntArray) => confirmThatMyFunctionOnSortedIntArraysWorks(a.value) }