Slides for my talk at PHP Barcelona 2010 on October 29th

1. Architecture and testability Listen to your tests on steroids Giorgio Sironi

3. Writer for DZone[, php|architect]

4. Bachelor of Computer Engineering @ PoliMi cum laude

6. Various techniques to favor ease of testing AND maintainability

8. …but not too much

9. Taking the first bullet

11. Evolving requirements

12. Iterative development (Agile)

13. Long-term maintenance

15. Functional tests (N objects), end-to-end tests (All objects)

16. Integration tests (external resources)

18. Open/closed

19. Dependency Inversion

24. Testable code -> Maintainable code

25. Maintainable code -> Happy programmer

27. A test is brittle?

28. A test is difficult to write?

31. Unit tests => loose coupling

32. Fast tests => in-memory isolation

33. 4 pillars...

35. Easy to change lifecycles and implementations

36. 1. Dependency Injection (without) <?php class Ferrari { private $engine ; public function __construct () { $this ->engine = new Engine (); } }

37. 1. Dependency Injection (with) <?php class Ferrari { private $engine ; public function __construct (Engine $engine ) { $this ->engine = $engine ; } }

39. Orthogonality of collaboration

40. 2. Avoid static methods (before) <?php class Collection { public function find ( $key ) { Sorter:: sort ( $this ); // ..search stuff } }

41. 2. Avoid using static methods (after) <?php class Collection { public function find ( $key ) { $this ->sorter-> sort ( $this ); // ..search stuff } }

43. Or: don't talk to strangers

44. 3. Law of Demeter (without) <?php class PC { public function powerOn () { $this ->mobo->cpu->cache -> powerOn (); } }

45. 3. Law of Demeter (with) <?php class PC { public function powerOn () { foreach ( $this ->powered as $item ) { /** @var Powered $item */ $item -> powerOn (); } } }

46. 3. Law of Demeter (with) <?php class PC { public function powerOn () { $this ->mobo-> powerOn (); } }

48. Hidden dependency

49. Global state

50. 4. Singleton vs. Factory <?php class Authenticator { public function login ( $user , $pass ) { Db:: select (...); } }

51. 4. Singleton vs. Factory <?php class Authenticator { public function __construct (Db $db ) { ... } public function login ( $user , $pass ) { $this ->db-> select (...); } }

53. Telling is better than looking around

54. Tests are a recipe for clean code

57. Growing Object-Oriented Software, Guided by Tests – Freeman, Price #goos

59. On Twitter: @giorgiosironi

60. Questions? Q/A