A PHP perspective on why start using tdd in a PHP project

1. TDD, a starting point
A PHP perspective...
Francesco Fullone, Ideato.it
ff AT ideato.it

2. Who am I
Francesco Fullone aka Fullo
- PHP developer since 1999
- President
- and Open Source Evangelist
- CEO @
- Nerd and geek

3. TDD ?

4. Test Driven
Development

5. Why test the code?

6. Developers are humans,
Humans are error-prone.

7. Software changes
and grows.

8. We need to confirm that
the code is working
after any changes.

9. xUNIT TDD approach.

11. PHPUnit.de

12. Easy to write
Easy to read
Isolated
Composable

13. An example:
The bowling kata
(courtesy grabbed from Sebastian Bergmann)

14. 10 frames
2 rolls to knock down the 10 pins
Score for a frame is the number of pins
knocked down
Bonus for a spare (all 10 pins knocked down in
two tries): next roll
Bonus for a strike (all 10 pins knocked down in
one try): next two rolls
Extra rolls for spare or strike in the 10th frame

15. <?php
require_once 'BowlingGame.php';
class BowlingGameTest extends PHPUnit_Framework_TestCase
{
}
?>

16. <?php
require_once 'BowlingGame.php';
class BowlingGameTest extends
PHPUnit_Framework_TestCase
{
public function testScoreForGutterGameIs0()
{
}
}

17. <?php
require_once 'BowlingGame.php';
class BowlingGameTest extends
PHPUnit_Framework_TestCase
{
public function testScoreForGutterGameIs0()
{
$game = new BowlingGame;
for ($i = 0; $i < 20; $i++) {
$game->roll(0);
}
$this->assertEquals(0, $game->score());
}
}

18. fullo@teletran ~ % phpunit --skeleton-class BowlingGameTest
PHPUnit 3.4.2 by Sebastian Bergmann.
Wrote skeleton for "BowlingGame" to "BowlingGame.php".
<?php
class BowlingGame
{
public function roll()
{
// Remove the following line when you
// implement this method.
throw new RuntimeException('Not yet implemented.');
}
public function score()
{
// Remove the following line when you
// implement this method.
throw new RuntimeException('Not yet implemented.');
}
}

19. fullo@teletran ~ % phpunit BowlingGameTest
PHPUnit 3.4.2 by Sebastian Bergmann.
E
Time: 0 seconds
There was 1 error:
1) BowlingGameTest::testScoreForGutterGameIs0
RuntimeException: Not yet implemented.
/home/fullo/BowlingGame.php:10
/home/fullo/BowlingGameTest.php:11
FAILURES!
Tests: 1, Assertions: 0, Errors: 1.

20. <?php
class BowlingGame
{
public function roll($pins)
{
}
public function score()
{
return 0;
}
}
?>

21. fullo@teletran ~ % phpunit --colors BowlingGameTest
PHPUnit 3.4.2 by Sebastian Bergmann.
.
Time: 0 seconds
OK (1 test, 1 assertion)

22. We have to write the
tests when the code is
fresh.

23. <?php
require_once 'BowlingGame.php';
class BowlingGameTest extends PHPUnit_Framework_TestCase
{
// …
public function testScoreForAllOnesIs20()
{
$game = new BowlingGame;
for ($i = 0; $i < 20; $i++) {
$game->roll(1);
}
$this->assertEquals(20, $game->score());
}
}

24. fullo@teletran ~ % phpunit –colors
BowlingGameTest
PHPUnit 3.4.2 by Sebastian Bergmann.
.F
Time: 0 seconds
There was 1 failure:
1) BowlingGameTest::testScoreForAllOnesIs20
Failed asserting that <integer:0> matches
expected value <integer:20>.
/home/fullo/BowlingGameTest.php:25
FAILURES!
Tests: 2, Assertions: 2, Failures: 1.

25. <?php
class BowlingGame
{
protected $rolls = array();
public function roll($pins)
{
$this->rolls[] = $pins;
}
public function score()
{
return array_sum($this->rolls);
}
}

26. <?php
require_once 'BowlingGame.php';
class BowlingGameTest extends PHPUnit_Framework_TestCase
{
// …
public function testScoreForOneSpareAnd3Is16()
{
$game = new BowlingGame;
$game->roll(5);
$game->roll(5);
$game->roll(3);
// a function to to roll X times
$this->rollMany(17, 0);
$this->assertEquals(16, $game->score());
}
}

27. fullo@teletran ~ % phpunit –colors
BowlingGameTest
PHPUnit 3.4.2 by Sebastian Bergmann.
..F
Time: 0 seconds
There was 1 failure:
1) BowlingGameTest::testScoreForOneSpareAnd3is16
Failed asserting that <integer:13> matches
expected value <integer:16>.
/home/fullo/BowlingGameTest.php:33
FAILURES!
Tests: 2, Assertions: 2, Failures: 1.

28. Tests can serve
as an executable
specification.

29. fullo@teletran ~ % phpunit --testdox BowlingGameTest
PHPUnit 3.4.2 by Sebastian Bergmann.
BowlingGame
[x] Score for gutter game is 0
[ ] Score for all ones is 20
[ ] Score for one spare and 3 is 16
[ ] Score for one strike and 3 and 4 is 24
[ ] Score for perfect game is 300

30. Why Unit Test.

31. To write only clean
and useful code.

32. To easily iterate in
development design.

33. To check for
regressions.

34. ?

35. For more info see Sebastian
Bergmann's Bowling Kata
Workshop!
http://www.slideshare.net/sebastian
_bergmann/quality-assurance-in-
php-projects-2164371

36. Francesco Fullone
ff AT ideato.it
skype: ffullone
via Quinto Bucci 205
47023 Cesena (FC)
info AT ideato.it
www.ideato.it