F# - FsCheck for Property-Based Testing

Yesterday I held a one-hour presentation of property-based testing, using the F# library FsCheck at realraum. It more or less covers the introductory documentation of FsCheck, just with fewer details and in a different order.

Although my talk was reasonably well received, questions, feedback and reflection result in some ideas for improvement:

• Give a real summary of the main-selling point of property based testing upfront.

  Declarative specification, automatic test-data generation and automatic test-case reduction are the important points.

  Here I thought it would be better to build the FsCheck explanation step-by-step; but I forgot that for somebody unfamiliar with PBT those key features are important to know whether one wants to listen at all.

• Spend more and better time on the very first step:
  How to define a property, and how to actually test it.

  There was one slide with the minimum necessary code for a console program which executes tests on a single property. Understanding this part is a prerequisite to make heads and tails of any following source excerpts. Next time I might spent another minute to explain every single step of it, including where any additional properties go.

• What is a property?

  “logical property, i.e. function with boolean result” does not cover it. We talk in context of automated software testing, so repeating some main differences between well-known testing frameworks and definition of properties help, as would more examples.

• Structure it.

  There is a clear distinction between general PBT stuff, and FsCheck basics. Help the brain by making this separation explicit.

• Give a heads-up on the structure of the talk.

  Tell them what you’ll tell them, tell them, tell them what you’ve told them. For some reason I forgot that.

• Provide more context for the code-examples.

  No damage done in repeating the first source code slide with changed properties. Not everyone wants to remember the content of one slide for the next 40 minutes.

• Unsure: Skip the base tutorial, show the cool stuff, explain basics on the way.

  Every time I think about it, and every time I decide against it; I’m afraid nobody would understand a thing of what I’m talking about. However, this time I explicitely got the feedback that this would have been more interesting.

  I have to try this once.

Well, besides that, (mostly) everything was fine…