JSVerify vs Scala Hedgehog

JSVerify is a free, open-source property-based testing library for JavaScript, inspired by QuickCheck. It generates inputs and checks whether a stated property holds across them. When a check fails, it attempts to shrink the generated input into a smaller counterexample. Properties can return Promises, allowing asynchronous methods to be tested. JSVerify is framework agnostic; the project names Mocha, nodeunit, and Jasmine as examples. The README instructs users to install it with `npm install jsverify` and says TypeScript typings are provided, though TypeScript specs cannot use the type DSL. Documented defaults are 100 tests and a maximum generated-value size of 50. Options cover test count, maximum generated size, quiet output, and random generator state. Generated values are deterministic when using primitives from the random module, and the RNG state can be set. The project is maintained by phadej and licensed under MIT. Its official site points to the GitHub README for API and usage documentation. The README cautions that exposed utility functions may change incompatibly, including in patch releases.

Scala Hedgehog is a property-based testing system for Scala that generates values to check properties and can simplify failing cases while preserving the generated values’ invariants. Range combinators let developers set the scope of generated numbers and collections. For stateful software, its abstract state machine testing can model systems such as web services and database layers. The project includes an SBT test runner and integration modules for Minitest and MUnit; its documentation also describes Gradle support through a Scala plugin. Documented Scala versions are 2.12, 2.13 and 3.3 or later. Binary dependencies for its modules are published through Maven Central, and the core module has no external dependencies. Scala Hedgehog is free, with no paid plans listed. The project describes its release as early and says its API may change before wider adoption. IntelliJ’s Scala plugin does not list Hedgehog among its built-in test frameworks, though Properties tests can be run as applications. The getting-started documentation assumes SBT; SBT 1.9.1 and later support the testing extension by default, while earlier versions require a testFrameworks setting.