F#-ception, wtf ?!?

220px-Inception_ver3Hi, its middle of summer so let us relax with a “coding for fun” post. The subject presented here came from a kind of “wtf contest” that we had with a colleague of mine on our free time. The objective was to write a unit test to tackle an existing code base using the weirdest approach. My contestant Gabriel is a brilliant developer, so in order to compete with him I had to bring something really absurd rather than technically sophisticated. So I came with the idea of executing F# code inlined in a powershell script invoked from F# code. Obviously, this is absolutely useless. However, it fitted well for the thematic of the  contest. In this post we will skip the “existing code base” part and focus on how to achieve this with a very simple example .

The first part of the job is to write some F# code that builds the powershell script with inlined F#. We will have to reference the F# code dom provider which can be downloaded here. Remark that for the sake of simplicity of this post we did not add any extra assemblies (see referencedAssemblies in script below).

Then let us try the FsToPs function with very simple case

Thus, the powershell code in simpleExample.ps1 looks like

You should be able to run this script in a powershell session. However, it is not finished for us, we have to invoke this script in F# and retrieve the returned value. The following snippet will do the job for us.

Then executed within MsTest framework….

…it works!

TestPassed

I’d like to thank Gabriel for being fair play by helping me to debug the first version of F#-ception.

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