Hi I've decided to take a deep dive into kotest property-testing and stuck a little bit. I want to w...

# kotest

[Ignat Simonenko]

Hi
I've decided to take a deep dive into kotest property-testing and stuck a little bit. I want to write a simple property test for Two Sum problem, so I need to generate random IntArray and Int that will be sum of two random elements of the generated array. I had no problems with the first Arb: Arb.list(<http://Arb.int|Arb.int>()).map { it.toIntArray() } but couldn't find a solution for the second one. Could someone advise something or I choose the wrong direction?

[sam]

What is the property that you are looking to test ?

[Ignat Simonenko]

I'm testing that sum of elements by indices returned by a given function is equal to passed one
As an example:

forAll (Arb.???) { array, sum ->
    val (first, second) = twoSum.find(array, sum)
    array[first] + array[second] == sum
}

I expect Arbs that will generate a random array and sum of two random unequal values from a given array, like array = [1, 2, 3, 5, 7] and sum = 9 as sum of 2 and 7, my function'll return [1, 4] indices then

[sam]

the problem is, the sum needs to appear in the array right, so you need your 2nd arb to know about the possible values in the first arb ?

[Ignat Simonenko]

yep