Is it possible to create a linear progression in ScalaCheck generator

Question

I have a newbie question for ScalaCheck which I am playing around with for the first time. Is it possible to create a Gen[Int] which will progress linearly from say 0 to N.

Such that when I use forAll in ScalaCheck it will increase the input Int by 1.

I would like this example to test with an increasing value

"Increase" should "always increase" in {
  forAll(validNumbers){ i:Int =>
    increase(i) should be (i + 1)
  }
}

Maybe this destroys ScalaChecks purpose and I should just test this way in ScalaTest.

score 1 · Accepted Answer · answered Jul 03 '14 at 14:37

1

You could do something like this:

def validNumbers(n: Int): Gen[Int] = Gen.resultOf[Int, Int] {
  new (Int => Int) {
    val current = (0 to n).iterator

    def apply(i: Int): Int = {
      if(current.hasNext) current.next else sys.error("No more numbers")
    }
  }
}

However I think you are indeed right, that this destroys ScalaChecks purpose. A simple for-loop would do better in this case.

answered Jul 03 '14 at 14:37

Volker Stampa

849
6
10

Thanks for that - you are right a simple for loop in ScalaTest is much better for my current need. – Mellson Jul 03 '14 at 15:55

Is it possible to create a linear progression in ScalaCheck generator

1 Answers1