The document explains Test Driven Development (TDD) as a guided coding technique that emphasizes writing tests before code, involving three main steps: writing a failing test, coding to pass it, and refactoring. It discusses its benefits in simplifying design and enhancing code quality, while also suggesting when to use or avoid TDD based on the complexity of the application. Finally, it provides a practical exercise involving the 'FizzBuzz' programming challenge.

1. Test Driven Development
Erinda Jaupaj
@ErindaJaupi
Valentina Servile
@EsseValentina
goes to

2. Introduction
What is Test Driven Development?

3. Introduction
What is Test Driven Development?

4. Introduction
What is Test Driven Development?
Maybe we should first ask ourselves...

5. Introduction
What is Test Driven Development?
What is a Test?

6. Introduction: what is a test?
A test is an assertion about how your
code should work

7. Introduction: what is a test?
It’s automated

8. Introduction: what is a test?
It has a binary output
(It’s either passing or failing)

9. Introduction: what is a test?
It begins with a precondition
(setup)

10. Introduction: what is a test?
It invokes a unit of work in the system
(trigger)

11. Introduction: what is a test?
It makes an assertion about the result

12. Setting up the
precondition
Invoking the
desired behavior
Asserting about
what happened

13. Patterns
Back to our
main topic...

14. Introduction
What is Test Driven Development?

15. Introduction
What is Test Driven Development?
It’s a technique where you let tests
guide your development workflow

16. Introduction: how do I TDD?
It works in 3 steps:

17. Introduction: how do I TDD?
It works in 3 steps:
• Write a failing test

18. Introduction: how do I TDD?
It works in 3 steps:
• Write a failing test
• Write just enough code to make it pass

19. Introduction: how do I TDD?
It works in 3 steps:
• Write a failing test
• Write just enough code to make it pass
• Refactor your mess

20. Introduction: how do I TDD?
It works in 3 steps:
• Write a failing test
• Write just enough code to make it pass
• Refactor your mess
Rinse and
Repeat!

21. Introduction: how do I TDD?
REFACTOR
FAIL
PASS
TDD

22. Introduction
What a waste
Of time!!!
Just make it work!!!

23. Patterns
TDD
Hands on

24. TDD Hands on
The requirements:
• Print numbers in sequence
• If the number is divisible by 3, print “Fizz”
• If the number is divisible by 5, print “Buzz”
• If divisible by both, print “FizzBuzz”

25. Patterns
The
FizzBuzz Kata

26. Patterns
Ta-Da!

27. Wrapping up: what is TDD for?
Okay, so what?

28. Wrapping up: what is TDD for?
But...

29. Wrapping up: what is TDD for? ...Design!
You HAVE to think of the edge cases

30. Wrapping up: what is TDD for? ...Design!
It often leads you to a simpler solution

31. Wrapping up: what is TDD for? ...Design!
Makes you write pretty object interfaces

32. Wrapping up: what is TDD for? ...Design!
You HAVE to think OO. And keep it simple.

33. Wrapping up: what is TDD for? ...Design!
It’s easy to add new features!

34. Wrapping up: what is TDD for? ...also, tests
...and to check if you broke the old ones

35. Wrapping up: what is TDD for? ...also, tests
...I’ll write my tests after.

36. Wrapping up: what is TDD for? ...also, tests
The code is self documented

37. TDD vs Traditional

38. Wrapping up: when NOT to use TDD?
• The application has little to no
business logic (CRUD?)
• You are building a prototype
• Quality is not important

39. Wrapping up: when to use TDD?
• The application has complicated
business logic
• You don’t know how your
implementation will look like
• Correctness is crucial
• The project is gonna be long lived
and frequently retouched

40. Patterns
Give it a try!

41. www.xpeppers.com
/xpepperssrl@xpeppers
Thanks!
Any questions?

42. Resources:
• http://www.jamesshore.com/Agile-Book/test_driven_d
evelopment.html
• https://www.amazon.com/Test-Driven-Development-
Kent-Beck/dp/0321146530
• http://codingdojo.org/kata/