Kotlin Testing

kotest

4 Ways to Leverage Kotest Specs for More Robust Testing

Discover the power of Kotest, a versatile alternative to jUnit for writing tests in Kotlin. Guide into four unique Kotest spec styles: StringSpec, FunSpec, FreeSpec, and BehaviorSpec.

How to mock data class?

Short answer: you don't. Instead: create additional function. Examples in Kotlin.

Refactor

Breaking the Loop: A 5-Step Process to Refactor Your Old, Untestable Codebase and Improve Its Quality"

By following this 5-step process, you can break the loop of having an old, untestable codebase, and improve the quality, maintainability, and testability of your application over time.

Masterclass

Open Android Unit Testing Workshops – 20.05.2023

Masterclass on Android Unit Testing. Registration till 19.05.2023 20:00.

idioms

Idiomatic Kotlin in tests: idiomatic stubbings

In this article we will explore several ways of creating stubs… using Kotlin idioms.

Android

Unit testing on Android – test pyramide

Are you programming for Android and wondering how to write tests for your app? Or maybe you don't have any tests in your project and don't know how to live? Get to know my philosophy of creating tests for Android.

Intro to jUnit5 for Android Developers (free course)

Here is a... mini-course introducing to jUnit5 in Kotlin, which will allow you to quickly jump into the new version of the testing framework.

mocking

De-mock your tests: practical recipes

How to mock without framework? Examples of de-mocking test code as presented on Droidcon Berlin 2022.

Stubbing with doAnswer vs doReturn – what's the difference?

Most of the times while stubbing with Mockito or MockK you will use doReturn construction. But do you know, that you can stub your test double method in other way – with doAnswer. Let's take a look a both stubbing types.

mockito

How to mock final classes with Mockito? (Kotlin & Java)

Mockito cannot mock/spy because your class is final class? Here's solution with using MockMacker.

basics

How to use jUnit4 & jUnit5 in one project?

When you have existing test suite containing jUni4 tests and you want to migrate slowly to jUnit5 to make use of new APIs and modern test engine, you may encounter some issues – not all tests will be visible in reports.

libraries

Libraries for Kotlin & JVM Testing

JVM and Kotlin testing libraries - Gradle dependencies and latest versions.

mock-static

Don't mock static: test Timber Logger with trees

Learn how to create custom Timber Tree to test log outputs in unit tests. Mocking Timber, unit testing logs.

mock-static

Don't mock static: test SLF4J Logger with appenders

Do you want to assert that SLF4J actually logged warn with proper message? Check this guide on how to mock logger in tests, in Kotlin and Java.

assertions

Building assertions with Strikt

Strikt is assertion library built for Kotlin with API which allows building multi assertions and gives us readable assertion errors.

IDE

Fighting Testing Boilerplate with IntelliJ IDEA Live Templates

Writing tests involves repeating some patterns over and over again. IntelliJ IDEA can shorten the process of test creation with the help of live templates.

coroutines

How to test a time-dependent coroutine

Check two approaches to test kotlin coroutines code depending on time.

IDE

IntelliJ Live Template that makes my life little easier

IntelliJ is great tool for developer productivity. Check how can we adjust IDE to our preferences. Tutorial: how to create custom live template?

Android

Why my date formatters test fails in CI and passes locally?

The story of debugging date time formatting issue. It passes locally, it fails on CI. How can it be?

Introducing stories: Quick Testing Tips

KotlinTesting.com now has stories!

junit

Nested tests with Junit5

Nested tests in Junit5 allows us grouping test cases. Check how to do this in presenter tests.

conference

Q & A from conferences 2020

Frequently Asked Questions - now I'm giving answers about things you've asked me on 2020 conferences.

mocking

How to use MockK in Kotlin? Stubbing and Mocking coroutines made easy.

How to mock suspend function in Kotlin? MockK is the solution. Code examples for coEvery, coAnswers, coReturns

ktor

Intro to testing Ktor controllers

Functional tests in Ktor - how to mock application server with TestApplicationEngine?

mockito

Using Mockito in Kotlin projects

How to use Mockito and Mockito-Kotlin? Refactoring Java Mockito based test suite to Mockito-Kotlin DSL

Android

Testing Retrofit calls with OkHttp MockWebServer

How to test Retrofit calls? Example of testing requests executed with Retrofit and OkHttp.

Android

An attempt to unit test generated DataBinding code

Story of an attempt to test the code generated by DataBinding library.

time

Testing time-based code with Joda Time

Testing time based properties with Joda Time - hints how to write micro DSL included!

kotest

Parameterized tests with Kotest

Creating parameterized tests in Kotlin: data driven testing, collection inspections and generating test cases with FreeSpec.

exceptions

Handling exceptions in tests: Junit & Kotest

Exceptions are crucial part of some Java APIs. How to assert that exceptions was thrown? In this note you will examples of various exception assertion techniques.

basics

Test execution basics: passed, failed, crashed

When the test passes, when it fails and why it crashes? In this short note we will try to find the answers for those questions.

Assert softly - when one assertion is not enough

kotest

Assert softly - when one assertion is not enough

It's usually in our best interest to keep one assertion per test method. Yet, situation when more than one check in single test method is present may occur.

Spek

Parametrized tests with Spek

Using Spek to generate test cases

MVVM

Building Unit Tests for ViewModel in TDD style

In his example we will try to implement VenueDetailsViewModel in TDD style. TDD (Test Driven Development) is development technique, where developer relies on unit tests created before actual implementation.

conference

Testing with Kotlin - Mobilization 2018 conference talk

repository

KotlinUnitTesting - repository with examples

This repository contains examples of basic unit tests written in Kotlin. In specific directories you can find gradle buildscript with needed dependencies and configuration, simple unit test and parameterized test.