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Random Testing for .NET
F# Other

Use forward slashes in paths in nuspec.

This hopefully makes it possible to build NuGet packages on linux.

What is FsCheck?

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 counter example.

FsCheck is a port of Haskell's QuickCheck. Important parts of the manual for using FsCheck is almost literally adapted from the QuickCheck manual. Any errors and omissions are entirely my responsibility.

Since v0.5, scalacheck has influenced FsCheck as well. Scalacheck is itself a port of QuickCheck to Scala.

FsCheck's generator combinators can be used in any testing framework to easily generate a number of random values for many types, and FsCheck itself integrates nicely with existing unit testing frameworks such as NUnit, xUnit, MSTest and MbUnit.



FsCheck follows Semantic Versioning 2.0.0.

All AppVeyor builds are available using the NuGet feed:

If using Paket, add the source at the top of paket.dependencies.


See the build history for a list of available versions:

Here are some options for specifying the dependency:

nuget FsCheck
nuget FsCheck prerelease
nuget FsCheck 2.0.4
nuget FsCheck 2.0.5-b247


More reading

  • Blog for announcements, change logs and other posts more or less related to FsCheck.
  • An interesting read about QuickCheck is in Chapter 11 of the excellent Real world Haskell book. The book is freely available online, but do the authors a favor and buy it, it's really worth it also for F# programmers.


Pull requests very welcome! Check out the issues marked up-for-grabs if you need any inspiration.

Checkout the project and run build.cmd on Windows or on Linux/OSX. That should pull in all the dependencies, build, run the tests and generate the documentation.

Then, open FsCheck.sln in Visual Studio on Windows or FsCheck-mono.sln on Linux/OSX in and start coding or writing documentation.

Building and testing from Visual Studio also works, to re-generate documentation quickly, execute docs/tools/generate.fsx in FSI. This should also work in Monodevelop and Xamarin, though I have not tested.

  • Windows on .NET:Build status
  • Linux on Mono: Build Status
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