Skip to content
Powerful, elegant and flexible test framework for Kotlin
Branch: master
Clone or download
Type Name Latest commit message Commit time
Failed to load latest commit information.
doc Fix typos in (#966) Sep 1, 2019
gradle/wrapper Bumped gradle to 5.51 Aug 16, 2019
kotlintest-assertions Bump Arrow version 0.10.0 (#1002) Sep 18, 2019
kotlintest-core Bump Arrow version 0.10.0 (#1002) Sep 18, 2019
kotlintest-extensions Tweaking override Sep 4, 2019
kotlintest-plugins/kotlintest-plugins-pitest Removed passed tests from log Sep 4, 2019
kotlintest-runner Bump Arrow version 0.10.0 (#1002) Sep 18, 2019
kotlintest-samples Bumped kotlin version Aug 14, 2019
kotlintest-tests Bump Arrow version 0.10.0 (#1002) Sep 18, 2019
.editorconfig Dot matches all in regex test Sep 4, 2019
.gitignore Introduced isolation mode for specs, reimplemented test runner to run… Jul 28, 2018
.travis.yml Updated gradle to use check not test for mpp Sep 3, 2019 Removed passed tests from log Sep 4, 2019
LICENSE Update LICENSE Mar 22, 2016 Update maven setup in README (#923) Aug 25, 2019
all.gpg.enc Added gpg keyring as encrypted file Jan 27, 2019
appveyor.yml AppVeyor: Create %HOME%\.gradle independently of the configuration (#293 Apr 15, 2018
build.gradle Bump Arrow version 0.10.0 (#1002) Sep 18, 2019 Release 3.4.0 Jul 21, 2019
gradlew Updated travis command to use gradle wrapper Mar 19, 2018
gradlew.bat Upgrade Gradle to the latest 4.10.3 release (#503) Dec 9, 2018
publish.gradle Fixed missing maven publish plugin Aug 20, 2019
settings.gradle Disabled junit4, removed junit5 specific fun and behavior spec, added… Sep 4, 2019
sksamuel.gpg.enc Added gpg keyring as encrypted file Jan 27, 2019 Updated deploy command to use publish Jan 28, 2019


Build Status Build status GitHub license

KotlinTest is a flexible and comprehensive testing tool for Kotlin.
Full documentation

For latest updates see Changelog


Test with Style

Write simple and beautiful tests with the StringSpec style:

class MyTests : StringSpec({
  "length should return size of string" {
    "hello".length shouldBe 5
  "startsWith should test for a prefix" {
    "world" should startWith("wor")

KotlinTest comes with several testing styles so you can choose one that fits your needs.

Multitude of Matchers

Use over 120 provided matchers to test assertions on many different types:




The withClue and asClue helpers can add extra context to assertions so failures are self explanatory:

withClue("Name should be present") { shouldNotBe null }

data class HttpResponse(val status: Int, body: String)
val response = HttpResponse(200, "the content")
response.asClue {
    it.status shouldBe 200
    it.body shouldBe "the content"

Nesting is allowed in both cases and will show all available clues.

Matchers are extension methods and so your IDE will auto complete. See the full list of matchers or write your own.

Let the Computer Generate Your Test Data

Use property based testing to test your code with automatically generated test data:

class PropertyExample: StringSpec() {
  init {
    "String size" {
      assertAll { a: String, b: String ->
        (a + b) should haveLength(a.length + b.length)

Check all the Tricky Cases With Data Driven Testing

Handle even an enormous amount of input parameter combinations easily with data driven tests:

class StringSpecExample : StringSpec({
  "maximum of two numbers" {
        row(1, 5, 5),
        row(1, 0, 1),
        row(0, 0, 0)
    ) { a, b, max ->
      Math.max(a, b) shouldBe max

Test Exceptions

Testing for exceptions is easy with KotlinTest:

val exception = shouldThrow<IllegalAccessException> {
  // code in here that you expect to throw an IllegalAccessException
exception.message should startWith("Something went wrong")

Fine Tune Test Execution

You can specify the number of invocations, parallelism, and a timeout for each test or for all tests. And you can group tests by tags or disable them conditionally. All you need is config:

class MySpec : StringSpec() {

  override val defaultTestCaseConfig = TestCaseConfig(invocations = 3)

  init {
    "should use config".config(timeout = 2.seconds, invocations = 10, threads = 2, tags = setOf(Database, Linux)) {
      // ...

And More ...

This page gives you just a short overview of KotlinTest. There are many more features:

See full documentation.



To use in gradle, configure your build to use the JUnit Platform. For Gradle 4.6 and higher this is as simple as adding useJUnitPlatform() inside the test block and then adding the KotlinTest dependency.

test {

dependencies {
  testImplementation 'io.kotlintest:kotlintest-runner-junit5:3.3.2'

or with Gradle Kotlin DSL

val test by tasks.getting(Test::class) {
    useJUnitPlatform { }

dependencies {

or with gradle and Android

android {
    testOptions {
        unitTests.all {

dependencies {
  testImplementation 'io.kotlintest:kotlintest-runner-junit5:3.3.2'


For maven you must configure the surefire plugin for junit tests.


And then add the KotlinTest JUnit5 runner to your build.

You can’t perform that action at this time.