QuickCheck vs QuickTheories

QuickCheck is a free Haskell library for testing program properties against randomly generated cases. Developers write specifications with QuickCheck combinators and can use combinators to define test-data generators and inspect generated-data distributions. It supports stateful testing, reproducible failures and shrinking failing cases. Monadic property testing is provided through the Test.QuickCheck.Monadic module. The package README describes adding QuickCheck to project dependencies for use in tests or a REPL. A companion package, quickcheck-instances, supplies instances for types in Haskell Platform packages, with additional dependencies. QuickCheck is licensed under BSD-3-Clause and lists dependencies including base, containers, random, splitmix, template-haskell and transformers. Hackage reports it tested with GHC versions from 8.10 up to but not including 9.15, as well as Hugs. A make-hugs script creates a Hugs-compatible version and may be useful for other non-GHC implementations. Hackage lists QuickCheck-2.18.0.0 as a downloadable Cabal source package. The listed package plan costs nothing.

QuickTheories is a free, open-source property-based testing library for Java 8. It checks general properties and invariants by generating random valid inputs, then automatically searches for smaller or simpler values that still fail a property. The library reports the seed for a falsified property, and tests can use fixed seeds for deterministic runs. Its generator DSL creates common Java types, constrains values, and combines or converts generators for custom types. QuickTheories works with JUnit, TestNG, and other test frameworks; `checkAssert` supports assertion libraries such as AssertJ and Hamcrest. The `forAll` API handles theories over one to four generated values. System properties configure seeds, example counts, and shrink attempts, while named profiles can reuse settings. An experimental coverage feature targets new code paths, but may reduce performance by about 10% and interfere with JaCoCo or other coverage systems. The project uses the Apache-2.0 license.