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_posts/2017-05-20-property-testing.md

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+---
+ID: 131
+post_title: Property testing
+author: dreat
+post_excerpt: ""
+layout: post
+permalink: >
+  http://dreat.info/2017/05/20/property-testing/
+published: true
+post_date: 2017-05-20 19:00:38
+---
+During ElixirConfEu in Barcelona, I learned about Property Testing. It looks pretty neat and it got me interested. Basics sound quite easy but there’s more than meets the eye and I’ve been reading/listening about it for a while.
+As I don’t feel comfortable enough to do a deep dive into the topic I will do an introduction to it. After I get a deeper understanding with some “real life” examples (or maybe doing them myself) I will write a follow-up.
+
+Property testing is a term originating from Haskell lib called QuickCheck. It was created to ease the pain of writing many tests. Instead of writing n specific unit test you can generate them.
+
+Using QuickCheck (here is the list of ports to your language of choice) you define a property of a piece of code you’re testing.
+
+For trivial example – if you were to write your own ordering function you can define few properties – if you order it twice the result won’t change, the only change is the position of elements (so you don’t hanger values) and so on.
+
+QuickCheck then generates data, runs n tests using this random data and if it finds failing case it executes something called shrinking – trying to find minimal failing case. It can ease up debugging or seeing straight away what’s wrong.
+
+While it’s all fun, I’m still not sure what are the cases in a commercial code where this is the best approach. Also, turns out that properties also form kind of patterns – and I’m yet to learn about all this.
+
+Nevertheless, I’m quite hyped and want to learn more – it seems more of easy to get, hard to master useful tool than a novelty, but only time will tell.