Great work on Kotest! I have a little question: ```data class Person( val name : String, val...

# kotest

[tieskedh]

Great work on Kotest!
I have a little question:

data class Person(
    val name : String,
    val age : Int
)

fun Arb.persons() = bind(
    string(), int()
) { name, age -> Person(name, age) }

@Test
fun test() = forAll(
    config = PropTestConfig(
        shrinkingMode = ShrinkingMode.Bounded(10)
    ), 
    Arb.persons()
){ it.age > 18 }

How can I use//create a shrinker for Person?

[sam]

This compiles:

data class Person(
   val name: String,
   val age: Int
)

val persons = Arb.bind(
   Arb.string(), <http://Arb.int|Arb.int>()
) { name, age -> Person(name, age) }

suspend fun test() {

   forAll(
      config = PropTestConfig(
         shrinkingMode = ShrinkingMode.Bounded(10)
      ),
      persons
   ) { it.age > 18 }
}

Bear in mind, the shrinking won't work for a binded type.

[tieskedh]

Thanks for the quick response!
Is there a way to compose StringShrinker and IntShrinker to get Person to shrink?

[sam]

Not currently. Could be added though. If you want to do a pr.

[tieskedh]

Do you mean that you explicitly should use shrink?

I tried with

forAll(
    config = PropTestConfig(shrinkingMode = ShrinkingMode.Unbounded),
    iterations = 1000,
    genA = Arb.string()
){
    println(it)
     "#" !in it
}

And it doesn't shrink either...

I think I'm still understanding the framework wrong, but if it should work, maybe it's because I'm using multiplatform?