PropEr vs Scala Hedgehog

PropEr is a free, open-source testing tool for Erlang programs. It performs automated, semi-random property-based testing and can generate input data from Erlang type declarations. Functions can be tested automatically from information in their Erlang specifications, while properties are written as Erlang expressions with predefined macros. PropEr also supports model-based random testing for stateful systems and targeted property-based testing using search-based techniques. Failing cases can be shrunk, and the project supports EUnit and Common Test. Constraints that Erlang’s type language cannot express can be handled with custom generators; filtering may keep trying random values until one passes. The generator language differs from Erlang’s type language for list expressions, including support for particular list lengths and element types. PropEr is self-hosted, supports Erlang, and is distributed under GPL version 3 or later. The guide describes installation from GitHub source, with make, or through Homebrew.

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.