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As one of the original designers and contributors of JUnit 5 I’ve always been intrigued by its basic idea to not only be a fresh start for a maintainable test framework but to also serve as a platform for all kinds of test engines: If anyone, so the idea, uses the platform to create their own test engine with it, IDE support and build tool support will come for free.

Since I’m no longer part of the JUnit 5 contributors’ team I wanted to try out if this platform idea really holds the value it’s promising.


Jqwik is a test engine of its own; built from the ground up. It focuses on both example-based and property-based testing and can therefore both replace standard Jupiter tests and add the additional perspective of QuickCheck-like randomized property checking.

I try hard to follow a few principles while developing Jqwik:

  • Every additional feature must solve a real testing problem that cannot be tackled by existing mechanism in a reasonably simple way.
  • Keeping the design simpler - and thereby more maintainable - is a feature itself and will often prevail over adding another feature of unproven or rather esoteric value.
  • Microtests are the foundation of scalable and maintainable Agile test automation. When in doubt, I’ll rank features that simplify microtesting over those that are intended to facilitate or enable integrated testing.


Please, please, please add your suggestion, ideas and bug reports using the project’s issue tracker on github.

Of course, you can also send in pull requests. Be prepared, though, that I’ll be very strict about what I accept, since I consider the first months of a project to be crucial for shaping the mid and long-term future of a project’s design and architecture.

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