CsCheck vs JSVerify

CsCheck is a free C# random testing library inspired by QuickCheck, intended for self-hosted use. Its composable Gen classes shrink generated cases automatically without Arb classes, and a shrunk case includes a seed that can reproduce a failure. The library supports random, model-based, metamorphic, performance, specification, regression, parallel and equality testing. Parallel tests compare outcomes with possible linearizations and support shrinking. Specification checks can enumerate reachable state spaces exhaustively or sample them, and can test whether declared faults are caught. Its Faster function statistically compares methods to assess whether one is faster and can run as a normal test across platforms. Example tests use TUnit, though the project says CsCheck can be used with any testing framework. The project page reports more than 1,000 F# tests using CsCheck in MKL.NET. NuGet lists version 4.9.1 and installation instructions for the .NET CLI and PackageReference. The project notes that generic recursion limits AOT compatibility; its Dbg module is temporary and may change between minor versions.

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.