Towards FsUnit 1.0

I have been giving a lot of consideration recently to an FsUnit 1.0 release and the direction of the project. The 0.6 release was meant to steer the project more in the direction of Behavioral-Driven Development but there is already a much better project out there for F# and BDD, NaturalSpec.

FsUnit 1.0 will instead be geared for more classical unit-testing and it now has two explicit goals: 1) to make unit-testing with F# more functional in nature and 2) to leverage existing unit-testing frameworks while at the same time exploring new possibilities offered by the F# language.

The target audience for this project is the F# developer (new and veteran alike) who wishes to use the same unit-testing framework that they’re already knowledgeable about: NUnit, MbUnit, xUnit, and MsTest. The new 0.9 release supports only NUnit but the others will be added soon.

The core syntax is pretty much the same as it has always been:

1 |> should equal 1

1 |> should not (equal 2)

[1] |> should contain 1

true |> should be True

But tests are once again contained within a test fixture and executed with a test runner. Here is the code for one of the project examples (UPDATE: removed non-standard use of self-identifier per reader's comments. Thanks, Alan!):

type LightBulb(state) =
    member x.On = state
    override x.ToString() =
        match x.On with
        | true  -> "On"
        | false -> "Off"

[<TestFixture>] 
type ``Given a LightBulb that has had its state set to true`` ()=
    let lightBulb = new LightBulb(true)

    [<Test>] member test.
     ``when I ask whether it is On it answers true.`` ()=
            lightBulb.On |> should be True

    [<Test>] member test.
     ``when I convert it to a string it becomes "On".`` ()=
            string lightBulb |> should equal "On"

[<TestFixture>]
type ``Given a LightBulb that has had its state set to false`` ()=
    let lightBulb = new LightBulb(false)
    
    [<Test>] member test.
     ``when I ask whether it is On it answers false.`` ()=
            lightBulb.On |> should be False
    
    [<Test>] member test.
     ``when I convert it to a string it becomes "Off".`` ()=
            string lightBulb |> should equal "Off"

I’m curious as to what people think about the use of back-ticked method names. I, for one, find it very helpful to be able to write in plain prose instead of CamelCase’d or snake_case’d method names.

Stay tuned to this blog for more information as FsUnit reaches a 1.0 release.