FsCheck vs Rust libtest

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 The project maintains version 3.x, but its documentation covers 2.x and is described as out of date and incomplete.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.

Rust libtest is Rust’s built-in test harness for compiling and running crate tests. Building with `rustc --test` links the executable to libtest; tests are free functions marked `#[test]`. Cargo’s `cargo test` handles building and running unit, integration, and documentation tests, including code samples extracted from library documentation comments. A test succeeds when it returns without an error; a panic or non-zero termination result marks failure. You can mark tests to expect a panic or to be ignored, filter by name, choose exact matches, skip matches, select ignored tests, or list tests and benchmarks without running them. Tests run in parallel by default, with the thread count configurable. The harness can capture output, display successful-test output, and format results as pretty, terse, or JSON; JSON formatting is unstable. Rust libtest is free and supports Linux, macOS, and Windows. Catching panics requires the unwind strategy; abort-strategy support is experimental. Benchmarking and custom harnesses are experimental and nightly-only.