Two weeks ago I went to Paul Stringer's course "Mastering TDD/BDD in iOS". After the two days, I was exhausted... During the course, we looked at all the theory, completed some exercises. Paul gave us lots of links and books to read and, quite frankly, I was feeling overwhelmed. I saw myself in front of the computer, with all those links to follow and read, and I didn't know what to do... So I laid back on my chair and closed my eyes and thought... What do I know about TDD?
Well, I know that it has laws:
I know I should follow the circle Red - Green - Refactoring:
This works well to enforce the three laws of TDD. And as Kent Beck said:
Make it work. Make it right. Make it fast.
And there are schools… well not physical ones:
The first one uses real objects/classes and it tests the state of those objects. The second tests collaboration between objects and for that it uses mocks. You have this article by Sandro Mancuso and this other by Jonathan Rasmusson that can help you distinguish them better.
As an iOS developer, I tend to be more of a mockist since I drive my tests from the UI. And developing an app in Swift has some challenging aspects since we don't have a Mocking framework... We do it all "by hand"...So yes knowing very well what kind of test double you need is a good thing. People tend to call them all mocks but as Martin Fowler said here:
Mocks aren't stubs
[...]Refactorings have counterparts called Transformations. Refactorings are simple operations that change the structure of code without changing its behavior. Transformations are simple operations that change the behavior of code.
TDD is not a design tool. It’s a software development workflow that prompts for code improvement in its lifecycle. [...] The great thing about TDD is that it is constantly asking us “Hey, can you make your code better? See how hard testing this class is becoming? OK, you made it work. Here’s your green bar. Now make it better.”
TDD must be approached like a discipline. You must have good habits to stick with it. Here is the TDD good habits manifesto. This came up for the first time in SoCraTes UK ‘16 in a form of a session facilitated by Mani Sarkar and Pedro Santos, where they challenged us to add or remove practices to their original draft that you can see here.
Well, it seems that I have a minimum knowledge about TDD. Still need to practice a lot, and apply what I have learned when coding. Here are some books that you could read:
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