FsCheck: Random Testing for .NET

FsCheck is a tool for testing .NET programs automatically. The programmer provides a specification of the program, in the form of properties which functions, methods or objects should satisfy, and FsCheck then tests that the properties hold in a large number of randomly generated cases. While writing the properties, you are actually writing a testable specification of your program. Specifications are expressed in F#, C# or VB, using combinators defined in the FsCheck library. FsCheck provides combinators to define properties, observe the distribution of test data, and define test data generators. When a property fails, FsCheck automatically displays a minimal counterexample.

FsCheck, NUnit and xUnit.NET plugins can be installed from NuGet using your favorite package manager.

Users have also created integrations with Expecto, Fuchu, AutoFixture and MSTest that you can find on NuGet.

The guides below have been updated to include FsCheck 3, but some explanations and examples may still be incomplete or out of date. The API reference is generated from the current code and describes the current public API. If a guide conflicts with the API reference, follow the API reference and please report the documentation issue.

The documentation and API docs for 2.x are not easily accessible anymore. The last commit of the 2.x documentation site is here.

FsCheck welcomes contributions of all kinds, big or small. See issues for inspiration. Feel free to open an issue to highlight specific problems or gaps, even if you're not sure it really is a problem. At worst you'll get an answer to your question.

Documentation

• QuickStart to get started.

• Properties describes FsCheck's language to express tests - in other frameworks these are often called parametrized tests or generative tests. FsCheck calls them properties.

• Generating test data describes how to guide FsCheck to generate better data or to stop it from generating data that doesn't make sense for what you're trying to test. FsCheck has a flexible language to describe test value generators and shrinkers, and apply them to your properties.

• Running Tests explains various ways to run FsCheck tests and how to integrate with unit testing frameworks.

• Model based testing, for testing stateful systems and objects. Since this is in the Experimental namespace, semantic versioning promises do not apply to this part of the API.

• Tips and tricks

• API Reference contains automatically generated documentation for all types, modules and functions.

Contributing and copyright

The project is hosted on GitHub where you can report issues, fork the project and submit pull requests. If you're adding new public API, please also consider adding samples that can be turned into documentation.

The library is available under the BSD license, which allows modification and redistribution for both commercial and non-commercial purposes. For more information see the License file in the GitHub repository.