Increasing Functional Test Coverage With QuickNet
Posted by Davy Brion on August 5th, 2009
A former coworker of mine posted an interesting preview to his new testing framework, called QuickNet. The example he used is pretty simple (a calculator), but the results are pretty interesting so be sure to check this out.
I’m hoping he’ll post some real world examples (or at least based a bit more on real word code) of QuickNet soon, and maybe even a brief comparison between QuickNet and something like Pex? 
August 6th, 2009 at 2:52 am
Thanks for the link. Both your suggestions are on my (rather large) todo list
) but they changed a couple of basic premises.
About the difference with Pex, there’s a short answer : Pex is a parameterized unit tester, QuickNet is a property based tester that models a program (or model, class, method) as a finite state machine.
Part of the long answer :
Recently Peli de Halleux published a paper with Pex patterns. The State Machine pattern on page 13 might seem familiar to anyone who has read the QuickNet preview (QN was born about a year ago btw, around the same time Pex made it’s first steps, I think we all saw the same talk By J.H). But look at the amount of classes and code, imagine having to string together a large number of transitions, or deal with a transition in one class that changes the state of another class. This will get out of hand. Pex is a unit tester, not really designed to handle state, but to make input generation as painless as possible. QuickNet is designed to handle both unit tests and integration tests (state).
In the Pex Tutorial chapter 6 it is mentioned that ‘Abstraction from the environment is necessary if you want to have a Pex-testable design.’. Now I truly agree that ‘Abstraction from the environment is necessary’ in order to have good code and if the program was developed in a TDD fashion, it probably has this feature, but in reality a lot of programs do not make this abstraction and I still want to test those. And I want to test them BEFORE I refactor them. QuickNet allows me to do that even if it touches a database or a filesystem or whatever.
I’m sure Pex derived it’s ideas from QuickCheck aswell just as QuickNet does (the Oracle in the example kind of gives it away
Too long a comment already so I’ll keep the explanation of the last statement for a post on my own blog
September 3rd, 2009 at 12:11 pm
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