JSVerify vs QCheck
JSVerify
jsverify.github.ioQCheck
github.comSide by side
| Figure | JSVerify | QCheck |
|---|---|---|
| Price from | Free | Free |
| Free plan | Yes | Yes |
| Free trial | — | — |
| Open source | — | — |
| Web | Yes | — |
| Linux | — | Yes |
| Self-hosted | Yes | — |
| Plans published | 1 | 1 |
| Spec score · Property-Based Testing Tools | 8.1 (#5) | 7.9 (#9) |
| Counterexamples | When a property fails, JSVerify attempts to find the smallest possible counterexample. | Generators can be paired with printers and shrinkers to display and minimize counterexamples when a property fails. |
| Installation | The project README instructs users to install the module with npm install jsverify. | QCheck can be installed through opam, and the README recommends qcheck-core for a minimal dependency set. |
| License | The GitHub repository identifies the project license as MIT. | The repository identifies its license as BSD-2-Clause and says the code is released under the BSD license. |
| Maintainer | The official site says the project is maintained by phadej. | The project page says it is maintained by c-cube, whose GitHub profile identifies Simon Cruanes. |
| Purpose | JSVerify is a property-based testing library for JavaScript, inspired by QuickCheck. | QCheck is a QuickCheck-inspired property-based testing library for OCaml. |
Plans
In their own words
JSVerify
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.
QCheck
QCheck is a property-based testing library for OCaml, inspired by QuickCheck. Rather than relying only on hand-picked examples, it provides combinators to generate values such as lists, arrays, tuples, recursive types, and algebraic types for checking properties. When a check fails, generators can be paired with printers and shrinkers to show and reduce counterexamples. QCheck2 builds shrinking into its generators, though the project describes that API as less battle-tested than QCheck. The package family includes qcheck-core, qcheck-ounit, qcheck-alcotest, qcheck, and ppx_deriving_qcheck; the last can derive generators from type declarations. Runner options include QCheck_base_runner in qcheck-core and QCheck_runner with OUnit compatibility in qcheck, with integration layers for OUnit and Alcotest. The project also points to qcheck-stm for sequential and parallel model-based tests and qcheck-lin for sequential consistency testing. Installation is available through opam, and the source can be built with make. The minimal qcheck-core package depends only on unix and dune. QCheck is free and licensed under BSD-2-Clause.