Hypothesis

Hypothesis integrates into your normal testing workflow. Getting started is as simple as installing a library and writing some code using it - no new services to run, no new test runners to learn.

Hypothesis currently has a fully featured open source Python implementation and a proof of concept Java implementation.

Hypothesis runs your tests against a much wider range of scenarios than a human tester could, finding edge cases in your code that you would otherwise have missed. It then turns them into simple and easy to understand failures that save you time and money compared to fixing them if they slipped through the cracks and a user had run into them instead.