Introduction

FsCheckUtils provides the facilities described in the following sections.

NuGet Package

FsCheckUtils is available as a NuGet package:

• https://www.nuget.org/packages/FsCheckUtils/

Convenience extension methods

Config

FsCheck.Config is an immutable class. The following extension methods create a new FsCheck.Config object with an updated value.

• Config.WithMaxTest
• Config.WithMaxFail
• Config.WithReplay
• Config.WithNoReplay
• Config.WithName
• Config.WithStartSize
• Config.WithEndSize
• Config.WithEvery
• Config.WithEveryShrink
• Config.WithArbitrary
• Config.WithRunner

In F#, we can do this:

let config = { Config.Default with MaxTest = 1000; Name = "My Config" }

With the above extension methods, we can achieve something pretty similar in C#:

var config = Config.Default
                    .WithMaxTest(1000)
                    .WithName("My Config");

Configuration

FsCheck.Fluent.Configuration is a mutable version of FsCheck.Config from the fluent part of the FsCheck API. SpecBuilder.Check takes a FsCheck.Fluent.Configuration parameter. The following method makes it easy to create an instance of FsCheck.Fluent.Configuration from an instance of FsCheck.Config.

• Config.ToConfiguration

As mentioned above, FsCheck.Fluent.Configuration is mutable. However, the following extension methods allow multiple properties to be set in a chained style.

• Configuration.WithMaxTest
• Configuration.WithMaxFail
• Configuration.WithName
• Configuration.WithStartSize
• Configuration.WithEndSize
• Configuration.WithEvery
• Configuration.WithEveryShrink
• Configuration.WithRunner

var configuration = Config.Default
                            .ToConfiguration()
                            .WithMaxTest(1000)
                            .WithName("My Configuration");

Wrappers around FsCheck operators

FsCheck's Prop operators e.g. .&., are visible to C# as static methods with names that begin with op_ and have symbol names in place of the symbols themselves e.g. op_DotAmpDot. It is possible to call these static methods from C# (as a normal method call - not as an infix operator). However, the names are very odd and ReSharper thinks they are errors (even in ReSharper 9.0 Update 1 - see the screenshot below). For these reasons, FsCheckUtils provides wrappers around these operators.

• PropExtensions.And (wraps .&.)
• PropExtensions.AndAll (a convenience method that applies .&. to a params array of properties)
• PropExtensions.Or (wraps .|.)
• PropExtensions.OrAll (a convenience method that applies .|. to a params array of properties)
• PropExtensions.Label (wraps |@)
• PropExtensions.Implies (wraps ==>)

Generators and combinators that are in ScalaCheck but not in FsCheck

• GenExtensions.PickValues (Gen.pick)
• GenExtensions.PickGenerators (Gen.pick)
• GenExtensions.SomeOfValues (Gen.someOf)
• GenExtensions.SomeOfGenerators (Gen.someOf)
• GenExtensions.RetryUntil (Gen.retryUntil)
• GenExtensions.NumChar (Gen.numChar)
• GenExtensions.AlphaUpperChar (Gen.alphaUpperChar)
• GenExtensions.AlphaLowerChar (Gen.alphaLowerChar)
• GenExtensions.AlphaChar (Gen.alphaChar)
• GenExtensions.AlphaNumChar (Gen.alphaNumChar)
• GenExtensions.AlphaStr (Gen.alphaStr)
• GenExtensions.NumStr (Gen.numStr)
• GenExtensions.Identifier (Gen.identifier)
• GenExtensions.Guid (Gen.uuid)
• GenExtensions.Zip (Gen.zip)

Documentation

Documentation, built from XML documentation comments using Sandcastle Help File Builder, can be found here:

• http://taylorjg.github.io/FsCheckUtils/index.html

TODO

• Ensure all public methods are covered by unit tests (only a couple aren't)
• Write some GitHub wiki articles about using FsCheck from C#

Using FsCheck from C#: some useful resources

• https://github.com/fsharp/FsCheck/blob/master/examples/FsCheck.CSharpExamples/Program.cs
• http://fortysix-and-two.blogspot.co.uk/2009/05/announcing-fscheck-06-dot-is-new-pipe.html
• http://bugsquash.blogspot.co.uk/2014/02/generating-immutable-instances-in-c.html
• https://github.com/taylorjg/AnIntroductionToFsCheckTesting
• https://github.com/taylorjg/ScalaCheckBookExamplesInFsCheck
• https://github.com/taylorjg/DontShrinkTests
• https://github.com/taylorjg/CustomShrinkerTests