[Unit-testing] F# development and unit testing?


I use NUnit, and it doesn't strike me as hard to read or onerous to write:

open NUnit.Framework

type myFixture() = class

    member self.myTest() =
       //test code


Since my code is a mix of F# and other .Net languages, I like the fact that I write the unit tests in basically the same fashion and with similar syntax in both F# and C#.


I just got started with F#, which is my first functional language. I have been working quasi-exclusively with C#, and enjoy a lot how F# leads me to re-think how I write code. One aspect I find a bit disorienting is the change in the process of writing code. I have been using TDD for years in C# now, and really appreciate to have unit tests to know where I am at.

So far, my process with F# has been to write some functions, play with them with the interactive console until I am "reasonably" sure they work, and tweak & combine. This works well on small-scale problems like the Euler Project, but I can't imagine building something large that way.

How do people approach unit testing and building a test suite for a F# program? Is there an equivalent to TDD? Any pointers or thoughts are appreciated.

As dglaubman suggests you can use NUnit. xUnit.net also provides support for this and works well with TestDriven.net. The code looks similar to NUnit tests but without the requirement to wrap the test in a containing type.


// Supply a module name here not a combination of module and namespace, otherwise
// F# cannot resolve individual tests nfrom the UI.
module NBody.DomainModel.FSharp.Tests

open System
open Xunit

open Internal

let CreateOctantBoundaryReordersMinMax() =
    let Max = VectorFloat(1.0, 1.0, 1.0)
    let Min = VectorFloat(-1.0, -1.0, -1.0)

    let result = OctantBoundary.create Min Max

    Assert.Equal(Min, result.Min)     
    Assert.Equal(Max, result.Max) 

You could have a look at FSUnit - though I haven't used it yet, it might worth a try. Certainly better than using for example (native) NUnit in F#.