example for shrinking

BusinessLogicTest.kt

import io.kotest.core.spec.style.FunSpec
import io.kotest.matchers.shouldBe
import io.kotest.property.*
import io.kotest.property.arbitrary.*

class BusinessLogicTests : FunSpec({

    fun isPrimeNumber(number: Int): Boolean {

        val root: Int = kotlin.math.floor(kotlin.math.sqrt(number.toDouble())).toInt()
        for (i in 2..root) {
            if (i % 2 == 0 && i != 2) {
                continue
            } else if (number % i == 0) {
                return false
            }
        }
        return true
    }
    test("素数の判定"){
        checkAll(PropTestConfig(shrinkingMode = ShrinkingMode.Bounded(50)),Arb.int(2..Int.MAX_VALUE)){
            i ->
            isPrimeNumber(i) shouldBe true
        }
    }
})

result.txt

Attempting to shrink failed arg 1776894914
Shrink #1: RTree(value=592298304, children=Lazy value not initialized yet.) fail
Shrink #2: RTree(value=197432768, children=Lazy value not initialized yet.) fail
Shrink #3: RTree(value=65810922, children=Lazy value not initialized yet.) fail
Shrink #4: RTree(value=21936974, children=Lazy value not initialized yet.) fail
Shrink #5: RTree(value=7312324, children=Lazy value not initialized yet.) fail
Shrink #6: RTree(value=2437441, children=Lazy value not initialized yet.) pass
Shrink #7: RTree(value=3656162, children=Lazy value not initialized yet.) fail
Shrink #8: RTree(value=1218720, children=Lazy value not initialized yet.) fail
Shrink #9: RTree(value=406240, children=Lazy value not initialized yet.) fail
Shrink #10: RTree(value=135413, children=Lazy value not initialized yet.) fail
Shrink #11: RTree(value=45137, children=Lazy value not initialized yet.) pass
Shrink #12: RTree(value=67706, children=Lazy value not initialized yet.) fail
Shrink #13: RTree(value=22568, children=Lazy value not initialized yet.) fail
Shrink #14: RTree(value=7522, children=Lazy value not initialized yet.) fail
Shrink #15: RTree(value=2507, children=Lazy value not initialized yet.) fail
Shrink #16: RTree(value=835, children=Lazy value not initialized yet.) fail
Shrink #17: RTree(value=278, children=Lazy value not initialized yet.) fail
Shrink #18: RTree(value=92, children=Lazy value not initialized yet.) fail
Shrink #19: RTree(value=30, children=Lazy value not initialized yet.) fail
Shrink #20: RTree(value=10, children=Lazy value not initialized yet.) fail
Shrink #21: RTree(value=3, children=Lazy value not initialized yet.) pass
Shrink #22: RTree(value=5, children=Lazy value not initialized yet.) pass
Shrink #23: RTree(value=6, children=Lazy value not initialized yet.) fail
Shrink #24: RTree(value=2, children=Lazy value not initialized yet.) pass
Shrink #25: RTree(value=4, children=Lazy value not initialized yet.) fail
Shrink #26: RTree(value=1, children=Lazy value not initialized yet.) pass
Shrink result (after 26 shrinks) => 4


Property failed after 2 attempts

	Arg 0: 4 (shrunk from 1776894914)

Caused by AssertionFailedError: expected:<true> but was:<false>