FsCheck vs scalaprops

FsCheck checks properties of.NET programs against randomly generated cases. Developers can express properties in F#, C# or VB, then run them with the built-in runner from an interactive session, a command-line program or a test framework. Integrations are documented for xUnit.net and NUnit, with user-created integrations for Expecto, Fuchu, AutoFixture and MSTest. When a property fails, FsCheck shrinks the input and shows a minimal counterexample. Developers can also define custom generators and shrinkers and group them in Arbitrary instances. The library supports parameterized cases and parallel execution, and its packages and NUnit and xUnit.NET plugins are available from NuGet. FsCheck is free: its listed plan is free, with a BSD license permitting commercial and non-commercial modification and redistribution. It runs on Linux, macOS and Windows. The project maintains version 3.x, but its documentation covers 2.x and is described as out of date and incomplete. Its model-based testing API is experimental and exempt from semantic-versioning guarantees.

Scalaprops is a free Scala property-based testing library for Linux. It generates test data, including non-constant scala.FunctionN values through Cogen, and lets each test define flexible parameters. Law checking is configurable, with identifiers that may use types other than String. Scalaz integration supplies laws plus Gen and Cogen instances for Scalaz types. Randomness uses an immutable generator rather than mutable scala.util.Random. Failed tests report their starting seed, which can be passed again with --seed= for repeatable runs. The README states support for Scala.js and Scala Native, using Mersenne Twister by default on JVM and Scala Native and Tiny Mersenne Twister on Scala.js. An sbt plugin adds scalapropsOnly selection by test class, method, and parameter. ScalapropsFramework and sbt are listed test runners. Parallel test execution is unsupported.