Lunch & Learn - Property Based Testing

Transcript

1. Lunch & Learn Property based Testing
2. What is a Property? Something always true in a given context
3. Could be Strong The total is the sum of the elements The answer is always 42 …
4. But most of the time, it’s weak The appointment is always in the future The invoice is never negative …
5. A test only validate one specific case
6. Wait, we also have parameterized tests
7. Yes but we go further with random generators
8. Let me introduce FsCheck A port of Haskell’s Quickcheck for .NET
9. Generator: easily generates a number of random values for many types Shrinker: tries to find the mininal counter example that still fails the property
11. Property based testing don’t replace unit testing
12. Property based testing test a lot of random cases cheaply
13. Random??? So what does green mean? Testing show the presence, not the absence of bug E. W. Dijktra
14. Finding good properties is hard
15. But it is worth to think about general properties of your business
16. Thanks QuickCheck: A Lightweight Tool for Random Testing of Haskell Programs http://www.cs.tufts.edu/~nr/cs257/archive/john-hughes/quick.pdf An introduction to property-based testing http://fsharpforfunandprofit.com/posts/property-based-testing/ FsCheck https://fscheck.github.io/FsCheck/