Kotlin Testing

Covers the full Kotlin testing stack with Kotest spec styles, MockK for mocking, coroutine testing, and Kover coverage configuration. Includes a proper TDD walkthrough showing the RED-GREEN-REFACTOR cycle with a real email validator example, which is rare to see documented this clearly. The spec style comparisons (StringSpec, FunSpec, BehaviorSpec, DescribeSpec) are useful if you're picking a testing DSL for your team. Kotest matchers section gives you the common assertions without digging through docs. This is opinionated toward idiomatic Kotlin testing rather than JUnit, so expect property-based testing patterns and coroutine-aware mocks. The Ktor testApplication section suggests it's aimed at backend services, not Android.

skills.sh installs: 4.8K
GitHub stars: 229.1K
last updated: Jul 14, 2026

View on GitHub

Install

$ npx -y skills add affaan-m/everything-claude-code --skill kotlin-testing --agent claude-code

Installs into .claude/skills of the current project.

Files

Kotlin Testing Patterns

Comprehensive Kotlin testing patterns for writing reliable, maintainable tests following TDD methodology with Kotest and MockK.

When to Use

Writing new Kotlin functions or classes
Adding test coverage to existing Kotlin code
Implementing property-based tests
Following TDD workflow in Kotlin projects
Configuring Kover for code coverage

How It Works

Identify target code — Find the function, class, or module to test
Write a Kotest spec — Choose a spec style (StringSpec, FunSpec, BehaviorSpec) matching the test scope
Mock dependencies — Use MockK to isolate the unit under test
Run tests (RED) — Verify the test fails with the expected error
Implement code (GREEN) — Write minimal code to pass the test
Refactor — Improve the implementation while keeping tests green
Check coverage — Run ./gradlew koverHtmlReport and verify 80%+ coverage