FsCheck 3.0.0-beta1

This is a prerelease version of FsCheck.

There is a newer version of this package available.
See the version list below for details.

dotnet add package FsCheck --version 3.0.0-beta1

NuGet\Install-Package FsCheck -Version 3.0.0-beta1

This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package.

<PackageReference Include="FsCheck" Version="3.0.0-beta1" />

For projects that support PackageReference, copy this XML node into the project file to reference the package.

<PackageVersion Include="FsCheck" Version="3.0.0-beta1" />
                    

                            Directory.Packages.props

<PackageReference Include="FsCheck" />
                    

                            Project file

For projects that support Central Package Management (CPM), copy this XML node into the solution Directory.Packages.props file to version the package.

paket add FsCheck --version 3.0.0-beta1

The NuGet Team does not provide support for this client. Please contact its maintainers for support.

#r "nuget: FsCheck, 3.0.0-beta1"

#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package.

#:package FsCheck@3.0.0-beta1

#:package directive can be used in C# file-based apps starting in .NET 10 preview 4. Copy this into a .cs file before any lines of code to reference the package.

#addin nuget:?package=FsCheck&version=3.0.0-beta1&prerelease
                    

                            Install as a Cake Addin

#tool nuget:?package=FsCheck&version=3.0.0-beta1&prerelease
                    

                            Install as a Cake Tool

The NuGet Team does not provide support for this client. Please contact its maintainers for support.

FsCheck is a tool for testing .NET programs automatically. You provide 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. Such properties are actually a testable specification of your program.

Properties are written in F#, C# or VB. FsCheck helps you to define properties, observe the distribution of test data, and define test data generators. Crucially, when a property fails, FsCheck automatically displays a minimal counter example.

Product	Compatible and additional computed target framework versions.
.NET	net5.0 was computed. net5.0-windows was computed. net6.0 was computed. net6.0-android was computed. net6.0-ios was computed. net6.0-maccatalyst was computed. net6.0-macos was computed. net6.0-tvos was computed. net6.0-windows was computed. net7.0 was computed. net7.0-android was computed. net7.0-ios was computed. net7.0-maccatalyst was computed. net7.0-macos was computed. net7.0-tvos was computed. net7.0-windows was computed. net8.0 was computed. net8.0-android was computed. net8.0-browser was computed. net8.0-ios was computed. net8.0-maccatalyst was computed. net8.0-macos was computed. net8.0-tvos was computed. net8.0-windows was computed. net9.0 was computed. net9.0-android was computed. net9.0-browser was computed. net9.0-ios was computed. net9.0-maccatalyst was computed. net9.0-macos was computed. net9.0-tvos was computed. net9.0-windows was computed. net10.0 was computed. net10.0-android was computed. net10.0-browser was computed. net10.0-ios was computed. net10.0-maccatalyst was computed. net10.0-macos was computed. net10.0-tvos was computed. net10.0-windows was computed.
.NET Core	netcoreapp2.0 was computed. netcoreapp2.1 was computed. netcoreapp2.2 was computed. netcoreapp3.0 was computed. netcoreapp3.1 was computed.
.NET Standard	netstandard2.0 is compatible. netstandard2.1 was computed.
.NET Framework	net461 was computed. net462 was computed. net463 was computed. net47 was computed. net471 was computed. net472 was computed. net48 was computed. net481 was computed.
MonoAndroid	monoandroid was computed.
MonoMac	monomac was computed.
MonoTouch	monotouch was computed.
Tizen	tizen40 was computed. tizen60 was computed.
Xamarin.iOS	xamarinios was computed.
Xamarin.Mac	xamarinmac was computed.
Xamarin.TVOS	xamarintvos was computed.
Xamarin.WatchOS	xamarinwatchos was computed.

Compatible target framework(s)

Included target framework(s) (in package)

Learn more about Target Frameworks and .NET Standard.

.NETStandard 2.0
- FSharp.Core (>= 4.5.0)

NuGet packages (34)

Showing the top 5 NuGet packages that depend on FsCheck:

Package	Downloads
FsCheck.Xunit FsCheck.Xunit integrates FsCheck with xUnit.NET by adding a PropertyAttribute that runs FsCheck tests, similar to xUnit.NET's FactAttribute. All the options normally available in vanilla FsCheck via configuration can be controlled via the PropertyAttribute.	6.1M
FsCheck.NUnit FsCheck.NUnit integrates FsCheck with NUnit by adding a PropertyAttribute that runs FsCheck tests, similar to NUnit TestAttribute. All the options normally available in vanilla FsCheck via configuration can be controlled via the PropertyAttribute.	1.8M
Expecto.FsCheck Property testing for Expecto, powered by FsCheck	1.1M
AutoFixture.Idioms.FsCheck Ubiquitous use of AutoFixture for unit testing has given rise to a number of idiomatic unit tests - unit tests that tend to follow common templates. The AutoFixture Idioms.FsCheck library encapsulates these idioms into reusable classes and methods.	371.9K
MBrace.Tests A collection of abstract NUnit-based test suites for evaluating MBrace runtime implementations.	138.1K

GitHub repositories (21)

Showing the top 20 popular GitHub repositories that depend on FsCheck:

Repository	Stars
dotnet/runtime .NET is a cross-platform runtime for cloud, mobile, desktop, and IoT apps.	17.9K
akkadotnet/akka.net Canonical actor model implementation for .NET with local + distributed actors in C# and F#.	5.1K
commandlineparser/commandline The best C# command line parser that brings standardized *nix getopt style, for .NET. Includes F# support	4.8K
thomhurst/TUnit A modern, fast and flexible .NET testing framework	3.9K
AIDotNet/OpenDeepWiki OpenDeepWiki is the open-source version of the DeepWiki project, aiming to provide a powerful knowledge management and collaboration platform. The project is mainly developed using C# and TypeScript, supporting modular design, and is easy to expand and customize.	3.2K
microsoft/onefuzz A self-hosted Fuzzing-As-A-Service platform	2.8K
NeutroniumCore/Neutronium 🚀 Build .NET desktop applications using HTML, CSS and javascript.	1.4K
dotnet/dotnet Home of .NET's Virtual Monolithic Repository which includes all the code needed to build the .NET SDK.	1.1K
SolrNet/SolrNet Solr client for .Net	955
la-yumba/functional-csharp-code Code samples for Functional Programming in C#	613
TolikPylypchuk/SharpHook SharpHook provides a cross-platform global keyboard and mouse hook, event simulation, and text entry simulation for .NET	498
helios-io/helios reactive socket middleware for .NET	449
exercism/csharp Exercism exercises in C#.	416
VSadov/Satori Experimenting with dotnet runtime.	363
viciousviper/DokanCloudFS A virtual filesystem for various publicly accessible Cloud storage services on the Microsoft Windows platform.	321
serdedotnet/serde Serde.NET is a C# port of the popular Serde serialization library for Rust	214
la-yumba/functional-csharp-code-2	130
oskardudycz/Ogooreck Sneaky Testing Library in BDD style	126
Vonage/vonage-dotnet-sdk Vonage REST API client for .NET, written in C#. API support for SMS, Voice, Text-to-Speech, Numbers, Verify (2FA) and more.	119
petabridge/TurboMqtt The fastest Message Queue Telemetry Transport (MQTT) client for .NET.	111

Version	Downloads	Last Updated
3.3.3	36,687	4/26/2026
3.3.2	597,605	11/9/2025
3.3.1	158,157	8/24/2025
3.3.0	167,208	6/3/2025
3.2.0	98,893	4/10/2025
3.1.0	249,792	1/30/2025
3.0.1	27,151	1/22/2025
3.0.0	107,918	1/7/2025
3.0.0-rc3	163,727	3/3/2024
3.0.0-rc2	1,852	2/25/2024
3.0.0-rc1	61,240	7/23/2023
3.0.0-beta2	93,734	1/8/2022
3.0.0-beta1	16,107	9/5/2021
2.16.6	2,392,773	7/1/2023
2.16.5	1,297,301	6/1/2022
2.16.4	721,519	1/8/2022
2.16.3	326,870	9/4/2021
2.16.2	11,904	8/30/2021
2.16.0	67,076	8/13/2021

Backwards incompatible*: Refactor and split of the `Gen` and `Arbitrary` APIs into `FsCheck.FSharp` and `FsCheck.Fluent`. This is a first step in splitting the entire API into a functional (for F# consumers) and fluent (for C# and VB.NET consumers) interface. This should be clearer for both kinds of consumers.
By and large, if you are an F# user, now `open FsCheck.FSharp` in addition to `open FsCheck`. If you are a C# or VB.NET user, add `using FsCheck.Fluent`.
Backwards incompatible*: redesigned API for per-type Arbitrary instance discovery and lookup. There is no longer a single global, mutable map of type to Arbitrary instances, instead there are any number of immutable `IArbMap`s that can be configured at your leisure, and set via `Config.WithArbitrary` on the test.
Detailed changes to `FsCheck.FSharp.Gen`: Added `RequireQualifiedAccess`. Added `apply` and `bind`. Renamed `collect` and `sequence` to `collect/sequenceToList/Array/Seq` for clarity. Removed `unzip` and `unzip3` - their implementation is problematic, and it's hard to see a use case for them. Removed `subListOfToIlist`, `subListOfArr` - these returned `IList<'T>` types. Untupled `rows,cols` arguments in `array2DOfDim`.
Detailed changes to `FsCheck.Fluent.Gen`: Split into non-extension methods on `Gen` and extension methods on `Gen<T>` type in `GenExtensions`. Removed `Gen.Apply` - not useful without partial application. `Two`, `Three`, `Four` and `Zip` now output ValueTuples, which is idiomatic in modern C#, and are only visible as extension methods on `Gen<T>`. Removed the overloads of `Zip` with arity 3. Changed the return type of methods that returned `IList<T>` previously to `List<T>`. Split the `Sample` method with optional arguments in three overloads, this is better for backwards compatibilty going forward.
Detailed changes to `FsCheck.FSharp.Arb`: Removed `fromGenShrinkFunc`. Removed `register`, `registerByType`, `from`, `generate` and `shrink` - these are replaced by functions on `ArbMap`, resp. `mergeWith`, `mergeWithType`, `arbitrary` and `generate`. Made `Arb.Default` internal. Default types should now be looked up using `ArbMap`, e.g. `ArbMap.defaults |> ArbMap.arbitrary<list<int>>`.
Detailed changes to `FsCheck.Fluent.Arb`: Removed extension method `ToArbitrary` that took an F# function as argument for the shrinker. Renamad `Arb.From` methods to `Arbitrary.From` - C# does not tolerate ambiguity between using two types of the same name in the same namespace. Removed `Register`, `RegisterByType`, `From`, `Generate` and `Shrink` - these are replaced by methods on `ArbMap`, resp. `Merge<'T>`, `Merge`, `ArbFor` and `GeneratorFor`. Made `Arb.Default` internal. Default Arbitrary types should now be looked up using `ArbMap`, e.g. `ArbMap.Default.ArbFor<int[]>()`.
First pass at improving XML docs for Gen API.
Fixed bug in `try..with` computation expression builder.
Added support for `let!...and!...` syntax in computation expression builder.

FsCheck 3.0.0-beta1

.NETStandard 2.0

NuGet packages (34)

GitHub repositories (21)