San Francisco Software Craftsmanship Meetup Test Driven Developers Bay Area Meetup TDD Flow: The Mantra in Action” is a talk + hands-on about the mantra of TDD and its core patterns. Here are some questions for this talk: What is TDD? How to write a good test that fails? How to write code enough to make the test pass? How to remove duplication? How to refactor code? How to create clean code? Is TDD about testing or design? How small should a test be? Should I only write unit tests? Should I estimate TDD? How to use TDD with other agile methods like Scrum, Kanban or BDD? And finally, how to flow in TDD?

1. TDD FlowTDD Flow
@dionatanmoura
The Mantra in ActionThe Mantra in Action

2. TDD Flow
The Mantra in Action
● eXtreme Programming
● Test-Driven Development (TDD)
● Mantra
● TDD Patterns
– Red patterns
– Green patterns
– Refactoring patterns
● Hands-on

4. https://5com1001-0912.wikispaces.com/

5. http://commons.wikimedia.org/wiki/File:Creador_de_la_metodologia_xp.jpg
“Test-Driven Development (TDD) is a style of
development that drives development with tests”
Kent Beck

7. TDD is the shortest cycleTDD is the shortest cycle
in agile developmentin agile development

8. TDD Rules
1. Write new code only if you first
have a failing automated test
2. Eliminate duplication

9. Write a small automated
test that fails
Red
Code just enough to
make the test pass
GreenRemove duplication and
refactor to clean code
Refactor
The Mantra in Action!

10. TDD = TFD + Refactoring;

11. TFD
Test
First
Development
TDD = TFD + Refactoring;

12. Refactoring
To restructure
software by applying a
series of refactorings
without changing its
observable behavior.
Martin Fowler
http://martinfowler.com
TDD = TFD + Refactoring;

13. Refactoring for TDD
Observable Behavior
==
Tests

14. “The goal of TDD is clean code that works.”
Ron Jeffries
https://twitter.com/RonJeffries

15. Clean Code
http://programmer.97things.oreilly.com/wiki/index.php/Uncle_Bob

16. SmallSmall
StepsSteps
https://thisbucketlist.wordpress.com/2012/06/01/small-steps-will-take-you-far-eventually/

17. Remember...

19. TDD Patterns

20. TDD Patterns
Test n.
Test for TDD is a noum (n.) which means a
procedure to acceptance (or not)
that runs automatically

21. TDD Patterns
Test List
What should I test?
Write a list of all known tests
that will be needed to be implemented.

22. TDD Patterns
Test First
When should I write a test?
Before I code.

23. TDD Patterns
Assert First
When should I write the assert?
First.

24. TDD Patterns
Test Data
How do I represent the intent of
the data?
With a meaningful relationship between the expect and the
actual result.

25. Red Bar Patterns

26. Red Bar Patterns
One Step Test
Which test should I pick from
the list?
Learning X Confidence

27. Red Bar Patterns
Starter Test
Which test should I start?
By a variation of the operation that doesn’t do
anything, returning a constant.
Outside-in (skeleton)

28. Red Bar Patterns
Explanation Test
How to spread test automation?
Ask for and give explanations in terms of tests.

29. Red Bar Patterns
Learning Test
How to learn from externally
produced software?
Write a test before use that software.

30. Red Bar Patterns
Another Test
How to discuss something off
topic?
Add a test to the list,
and go back to the current test.

31. Red Bar Patterns
Regression Test
What to do with a reported bug?
Write a small test that fails that bug.

32. Red Bar Patterns
Break
What to do when I feel tired or
stuck?
Take a break.

33. Red Bar Patterns
Do over
What to do when I feel lost?
Throw away the code and start over.

34. Red Bar Patterns
Cheap desk, Nice chair
What is the physical setup for TDD?
A really nice chair mostly.

35. Testing Patterns

36. Testing Patterns
Child Test
How to get a too big test case running?
Write the smallest test case that represents the
broken part of the bigger test case, and make it run.
Go back to the big test case.

37. Testing Patterns
Mock Object
How to test something that relies on an
expensive or complicated resource?
Create a fake version of the resource.

38. Testing Patterns
Crash Test Dummy
How to test error codes difficult to be
invoked?
Create a fake object for that.

39. Testing Patterns
Broken Test
How to leave a programming session (alone)?
Leave the last test broken.

40. Testing Patterns
Clean Check-in
How to leave a programming session (in pair
or in a team)?
Leave all the tests running.

41. Green Bar Patterns

42. Green Bar Patterns
Fake It (‘til you make it)
What is the first implementation to make a
test pass?
Return a constant.

43. Green Bar Patterns
Triangulate
How to drive abstraction?
Abstract when you have two or more examples.

44. Green Bar Patterns
Obvious Implementation
How should I implement simple
operations?
Just implement them.

45. Green Bar Patterns
One to Many
How to implement with collections?
Implement first without collections. Then make it work with
collections.

46. Extract
Inline
Introduce
Move
Pull up
Push Down
Remove
Replace
http://refactoring.com/catalog/
Class
Field
Interface
Method
Object
Parameter
Subclass
Superclass
Refactoring Patterns

47. Design Patterns

48. xUnit Patterns
Assertion
Boolean expressions with assert();
Fixture
Common objects for the tests with setUp();
External Fixture
Release external resources with tearDown();
Test Method
Represents a test case
Exception Test
Fail(); if the exception is not thrown
AllTests
Suite of all suites

49. However don’t forget...

51. JUnit Test Infected:
Programmers Love Writing Tests
http://junit.sourceforge.net/doc/testinfected/testing.htm

52. Is TDD only about
Unit Testing?

53. Is TDD a
testing technique?

54. “The focus of TDD is design.
Test is a (nice) side effect.”
Marco Trincardi

55. Is TDD Dead?
http://martinfowler.com/articles/is-tdd-dead/

56. RIP TDD (ironic)
https://www.facebook.com/notes/kent-beck/rip-tdd/750840194948847/

57. “To me the essence of the
question I think about that,
thinking about software design, I
don't care about TDD or not TDD.”
Kent Beck, Is TDD dead? Part II.

58. Does TDD lead you to a
good design?

59. "TDD isn't taking you anywhere.
You're making the decisions."
Kent Beck, Is TDD dead? Part II.

60. How to learn (more) TDD?

61. CraftsmanshipCraftsmanship
http://www.houshamadyan.org

62. PracticingPracticing
http://en.wikipedia.org/wiki/Dojo

63. Kata: TroLolo
(FizzBuzz)

64. Kata: DSL, Java
and ANTLR

65. Kata: Testing JavaKata: Testing Java
Web ApplicationsWeb Applications
outside the containeroutside the container

66. Kata: In-ContainerKata: In-Container
Testing Java withTesting Java with
ArquillianArquillian

67. Kata: RomanKata: Roman
NumbersNumbers

68. “Worried that TDD will slow down
your programmers? Don't. They
probably need slowing down.”
J. B. Rainsberger

69. Remember again...

70. http://blog.gravypower.net/

72. TDD FlowTDD Flow
@dionatanmoura
The Mantra in ActionThe Mantra in Action