Testing F# code with NUnit (Screen cast)

I demonstrate the basics of testing F# code with the NUnit unit testing framework. You can also see F# Visual Studio integration and the new F# interactive mode in action (WMV, 5MB); also on Google Video.

Links mentioned in the video: F#; NUnit.

There are a few mistakes and slips of the tongue. That's how you know it's totally unscripted and unedited. Don Syme caught the most important ones:

• #I and #r are much smoother ways to reference DLLs, e.g.:

  #I @"C:\WINDOWS\Microsoft.NET\Managed DirectX\v9.02.2904" ;;
  #I @"C:\WINDOWS\Microsoft.NET\DirectX for Managed Code\1.0.2902.0";;
  #I @"C:\WINDOWS\Microsoft.NET\DirectX for Managed Code\1.0.2905.0";;
  #I @"C:\WINDOWS\Microsoft.NET\Managed DirectX\v9.05.132" ;;
  #r @"Microsoft.DirectX.dll";;
  #r @"Microsoft.DirectX.Direct3D.dll" ;;
  #r @"Microsoft.DirectX.Direct3Dx.dll" ;;
  #nowarn "40"  // turn off "checked for initialization soundness" warnings

• Custom attributes:
  • In my internal version you now also go before “type”, “val”, “exception” and “let” in both .mli files and .ml files. However have just fixed a bug that caused them to be ignored when in this position.
  • Using the extension “Attribute” now permitted
• Beware “+” is overloaded on strings as of F# 1.1.0.4, so the following is well-typed!!!

  let rec sum l = match l with [] -> "" | h::t -> h+ sum t

That last one caught me totally off guard! The keen-eyed will notice that the type error comes from the use of sum.

Comments:

Unscripted? You're a natural! — Don Syme

Good stuff, thanks! — Aaron

hey Dominic: Its really cool to see the interop of languages at action. kudos! also great to see that we have a F# interpreter finally :). Keep the good stuff flowing. cheers, Vaibhav — Vaibhav

Excellent! How is the beer in Japan? — Adam Granicz

Yes indeed Dominic, how is the beer!? — Don Syme

Hi, I'm very interested in learning about F#. I realize this is an MS-based thing, but I have to say that it is very sad that things like this tutorial are done in such Windows-centric formats. WMV is not friendly to non-Widows folks (yeah, I know, the 0.01% of the world that is non-Widows folks :-). Still, thanks for putting up this tutorial, perhaps some day I'll get a chance to watch it... $0.02, sincerely. — R Duke

too fascinating! — leon