Kotest Example

build.gradle.kts

import org.jetbrains.kotlin.gradle.tasks.KotlinCompile

plugins {
    kotlin("jvm") version "1.6.10"
    application
}

group = "com.github.wpanas"
version = "1.0-SNAPSHOT"

repositories {
    mavenCentral()
}

dependencies {
    testImplementation("io.kotest:kotest-runner-junit5:5.2.1")
    testImplementation("io.kotest:kotest-property:5.2.1")
}

tasks.withType<Test>().configureEach {
    useJUnitPlatform()
}

tasks.withType<KotlinCompile> {
    kotlinOptions.jvmTarget = "11"
}

application {
    mainClass.set("MainKt")
}

isEven.kt

import io.kotest.core.spec.style.WordSpec
import io.kotest.matchers.shouldBe
import io.kotest.property.Arb
import io.kotest.property.arbitrary.filter
import io.kotest.property.arbitrary.int
import io.kotest.property.checkAll

fun isEven(int: Int) = int % 2 == 0

class IsEvenSpec : WordSpec({
    "isEven" should {
        "return true for even integers" {
            val evenIntegers = Arb.int().filter { it % 2 == 0 }

            checkAll(evenIntegers) { evenInteger ->
                isEven(evenInteger) shouldBe true
            }
        }

        "return false for odd integers" {
            val oddIntegers = Arb.int().filter { it % 2 == 1 }

            checkAll(oddIntegers) { oddInteger ->
                isEven(oddInteger) shouldBe false
            }
        }
    }
})