TestBalloon reaches flight level 1.0.0🔗
Kotlin testing made easy, everywhere.
After its initial publication at KotlinConf 2025, and 50 public releases, TestBalloon 1.0.0 is now stable. The Kotlin-first test framework has demonstrated making testing a joy across JVM, Android, JS, Wasm, and all Native targets (iOS, macOS, Linux, Windows).
This milestone is the result of building for today's Kotlin landscape from the ground up: a clean, concise, DSL-based API, battle-tested robustness at scale, and first-class support for the full breadth of the Kotlin ecosystem.
TestBalloon is ready for the upcoming Kotlin 2.4.0.
What is TestBalloon?🔗
TestBalloon is a Kotlin-first test framework that lets you write tests easily, as concisely as possible, and run them everywhere Kotlin runs — without compromise. It integrates seamlessly with Gradle, IntelliJ IDEA, Android Studio, and your existing toolchain. You can always keep using your favorite assertion library.
TestBalloon's small-surface API and the power of Kotlin keep testing easy as your projects grow, and as you scale up (more complex interactions) or out (across targets).
Highlights🔗
- Stable, production-ready API — the API surface has been carefully refined and is now stable with binary ABI guarantees.
- Kotlin Multiplatform — first-class support for JVM, Android (instrumented & host-side), JS, Wasm/JS, Wasm/WASI, all Native targets (iOS, macOS, Linux, Windows).
- Multi-level hierarchy — structure tests for clarity and sharing behavior, use coroutine context inheritance, selective parallel execution, flakiness handling.
- Parameterized tests — write a single test for many variants, see individual results in reports.
- Fixtures at every level — give each test a clean, fresh state, or share state across tests.
- Robolectric integration — fast, reliable, and configurable Android testing without an emulator.
- IntelliJ IDEA integration — run tests directly from editor windows.
- Conditional test selection — control test runs across all targets via environment variables and typesafe Kotlin expressions.
- Proven at scale — validated against real-world test sets of several hundred thousand to nearly 2 million tests.
- Extensive documentation — guides, how-tos, and a blog at the TestBalloon doc site.
Release variants🔗
| TestBalloon version | Supported Kotlin versions |
|---|---|
| 1.0.0-K2.4.0-Beta2 | 2.4.0-Beta2 … 2.4.0-RC |
| 1.0.0-K2.3.20 | 2.3.20 … 2.3.21 |
| 1.0.0-K2.3.0 | 2.3.0 … 2.3.10 |
| 1.0.0-K2.2.21 | 2.2.21 |
| 1.0.0-K2.2.0 | 2.2.0 … 2.2.20 |
| 1.0.0-K2.1.20 | 2.1.20 … 2.1.21 |
| 1.0.0-K2.1.0 | 2.1.0 … 2.1.10 |
| 1.0.0-K2.0.0 | 2.0.0 … 2.0.21 |
Thank you 🙏🔗
Thank you to everyone who filed issues, contributed feedback, tested early releases, and helped shape TestBalloon into what it is today. Here's to writing great tests!