Starting with Vaadin 25.1, browserless tests (previously known as UI unit tests) will become part of Vaadin’s free offering, licensed under Apache 2.0 like the core framework.
In the LLM-powered development era, fast and stable UI tests are essential for every application. We want every new Vaadin user to have access to first-party tooling for this from day one so building confidently with Vaadin stays fast, reliable, and scalable across teams.
What are browserless web UI tests?
Browserless UI tests are fast tests that execute your UI code directly inside the JVM, without starting a browser or using WebDriver. This approach is possible thanks to Vaadin's server-driven architecture. Because the UI is written in Java and runs on the server, you can validate the UI logic, such as component state, event handling, validation, routing, and the application logic triggered by user interactions, in-process with minimal setup and excellent stability.
This style of testing became popular in the Vaadin ecosystem thanks to Karibu Testing, a community-built Kotlin library that showed how effective browserless testing can be for Vaadin applications. Later, a similar capability from Vaadin, with a more Java oriented API, was introduced as TestBench UI unit testing, and now it is evolving further as browserless testing as part of Vaadin’s free offering.
End-to-end tests with Vaadin TestBench, Selenium, or Playwright still provide the highest confidence that a web app works across all layers, but they are typically much slower to run and can become a maintenance burden as applications evolve if overused. Typically, the best combination is to keep most tests browserless for speed and stability, and complement them with a smaller set of E2E tests based on your application’s requirements. Those form the essential part in your testing pyramid, above your browserless UI tests.
What’s changing
- Browserless UI testing becomes free in Vaadin 25.1
- There will be a new module and Java package. Existing TestBench UI unit tests keep working, thanks to a compatibility layer. We recommend migrating to use the new module though; the compatibility layer is intended as a transition path. JUnit 4 will be supported only in the compatibility layer.
You can follow the progress via a related GitHub issue.
What’s next for TestBench
Vaadin TestBench, and its traditional E2E tooling, remains a part of our commercial portfolio that we use to finance the development of the open source framework. We’re also currently concepting ways to strengthen TestBench further—especially around turning E2E flows into practical scalability testing. Our current proof-of-concept automatically creates Grafana k6 scenarios based on your existing TestBench tests.
Don’t hesitate to contact us, in case you’d like to help shape these concepts. We’d love to work with a few lighthouse customers to validate direction and usability.