PropCheck vs QuickTheories

PropCheck is a Ruby library for property-based testing: it generates inputs and checks whether assertions hold across them. When a generated example fails, it tries to simplify that case into a smaller counterexample. Built-in generators cover integers, floats, strings, symbols, arrays, hashes, sets, dates, times and datetimes. A generator DSL lets developers define their own, while the API also supports mapping and binding values, alternatives and weighted frequency choices.

Before, after and around hooks provide setup and cleanup around generated examples. The README gives usage examples for RSpec, MiniTest, test-unit and vanilla Ruby, and says the library has no external dependencies. PropCheck requires Ruby 2.5.1 or later and is released under the MIT License. It is available as a free Community library. Installation can be done through a Gemfile or with `gem install prop_check`. For generated examples involving a database, the README recommends cleaning database state around each example and mentions DatabaseCleaner. Stateful property testing is described as a possible future separate add-on.

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.