1. Fundamentals of unit testing in PHP usingPHPUnit Nicolas A. Bérard-Nault 5 May 2011

3. Improvinginternalqualityby increasingmaintainability

5. Use tests as documentation

8. Member of the xUnitfamily

9. Direct descendant of sUnitwritten by Kent Beck and jUnit, written by Beck and Erich GammaWebsite: http://www.phpunit.de Code coverageisprovidedusing the xDebug extension: http://www.xdebug.org

10. Your first PHPUnittest (1) Goal: test an implementation of ROT13 System under test: functionrot13($text) { $len = strlen($text); for ($i = 0; $i < $len; $i++) { $text{$i} = chr((ord($text{$i}) - ord('a') + 13) % 26 + ord('a')); } return$text; } Initial naïve approach: Formulateexpectedbehavior

11. Your first PHPUnittest (2) Class namehas Test suffix Base class for tests class Rot13Test extendsPHPUnit_Framework_TestCase { public functiontestWord() { $this->assertEquals('cheryl', rot13('purely')); } } Test methodhas test prefix Post-condition verification

12. Your first PHPUnittest (3) nicobn@nicobn-laptop:~$ phpunit rot13.php PHPUnit 3.5.5 by Sebastian Bergmann. . Time: 0 seconds, Memory: 3.50Mb OK (1 test, 1 assertion) The test passes but have wereallycovered all of our bases ?

13. Preconditions, invariants and postconditions functionrot13($text) { $len = strlen($text); for ($i = 0; $i < $len; $i++) { $text{$i} = chr((ord($text{$i}) - ord('a') + 13) % 26 + ord('a')); } return$text; } Precondition: $text must be a string Precondition: $text must belower case Invariant: non-alpha characters must remainunchanged Postcondition: each alpha character must bemoved 13 positions Wescrewed up ! How many more tests do weneed ?

14. NEWFLASH: It’s not a question of how awesomelyawesome of a programmer you are, but a question of methodology ! Sad panda issad

15. Test first ! (1) “Applying ROT13 to a piece of text merely requires examining its alphabetic characters and replacing each one by the letter 13 places further along in the alphabet, wrapping back to the beginning if necessary. A becomes N, B becomes O, and so on up to M, which becomes Z, then the sequence continues at the beginning of the alphabet: N becomes A, O becomes B, and so on to Z, which becomes M. Only those letters which occur in the English alphabet are affected; numbers, symbols, whitespace, and all other characters are left unchanged. Because there are 26 letters in the English alphabet and 26 = 2 × 13, the ROT13 function is its own inverse.” (Wikipedia)

16. Test first ! (2a) functionrot13($text) { } class Rot13Test extendsPHPUnit_Framework_TestCase { public function test_A_Lower() { $this->assertEquals('n', rot13('a')); } } There was 1 failure: 1) Rot13Test::test_A_Lower Failed asserting that two strings are equal. --- Expected +++ Actual @@ @@ -n +

17. Test first ! (2b) functionrot13($text) { return‘n’; } class Rot13Test extendsPHPUnit_Framework_TestCase { public function test_A_Lower() { $this->assertEquals('n', rot13('a')); } } PHPUnit 3.5.5 by Sebastian Bergmann. . Time: 1 second, Memory: 3.50Mb OK (1 test, 1 assertion)

18. Test first ! (2c) functionrot13($text) { returnchr(ord($text{0}) + 13); } class Rot13Test extendsPHPUnit_Framework_TestCase { public function test_A_Lower() { $this->assertEquals('n', rot13('a')); } } PHPUnit 3.5.5 by Sebastian Bergmann. . Time: 1 second, Memory: 3.50Mb OK (1 test, 1 assertion)

19. Test first ! (3a) functionrot13($text) { returnchr(ord($text{0}) + 13); } class Rot13Test extendsPHPUnit_Framework_TestCase { public function test_A_Lower() { $this->assertEquals('n', rot13('a')); } public function test_N_Lower() { $this->assertEquals(‘a', rot13(‘n')); } } FAIL !

20. Test first ! (3b) functionrot13($text) { return chr((ord($text{0}) - ord('a') + 13) % 26 + ord('a')); } class Rot13Test extendsPHPUnit_Framework_TestCase { public function test_A_Lower() { $this->assertEquals('n', rot13('a')); } public function test_N_Lower() { $this->assertEquals(‘a', rot13(‘n')); } } PASS !

21. Test first ! (4a) functionrot13($text) { return chr((ord($text{0}) - ord('a') + 13) % 26 + ord('a')); } class Rot13Test extendsPHPUnit_Framework_TestCase { public function test_A_Lower() { $this->assertEquals('n', rot13('a')); } public function test_N_Lower() { $this->assertEquals(‘a', rot13(‘n')); } public functiontest_Symbol() { $this->assertEquals('$', rot13('$')); } } FAIL !

22. Test first ! (4b) functionrot13($text) { if (!ctype_alnum($text{0})) { return$text{0}; } return chr((ord($text{0}) - ord('a') + 13) % 26 + ord('a')); } class Rot13Test extendsPHPUnit_Framework_TestCase { public function test_A_Lower() { $this->assertEquals('n', rot13('a')); } public function test_N_Lower() { $this->assertEquals(‘a', rot13(‘n')); } public functiontest_Symbol() { $this->assertEquals('$', rot13('$')); } } PASS !

23. Test first ! (5a) functionrot13($text) { if (!ctype_alnum($text{0})) { return$text{0}; } return chr((ord($text{0}) - ord('a') + 13) % 26 + ord('a')); } class Rot13Test extendsPHPUnit_Framework_TestCase { /* […] */ public functiontest_N_Upper() { $this->assertEquals('A', rot13('N')); } } FAIL !

24. Test first ! (5b) functionrot13($text) { if (!ctype_alnum($text{0})) { return$text{0}; } if (ctype_upper($text{0})) { $delta = ord('A'); } else { $delta = ord('a'); } return chr((ord($text{0}) - $delta + 13) % 26 + $delta); } class Rot13Test extendsPHPUnit_Framework_TestCase { /* […] */ public functiontest_N_Upper() { $this->assertEquals('A', rot13('N')); } } PASS !

25. Test first ! (6a) functionrot13($text) { if (!ctype_alnum($text{0})) { return$text{0}; } if (ctype_upper($text{0})) { $delta = ord('A'); } else { $delta = ord('a'); } return chr((ord($text{0}) - $delta + 13) % 26 + $delta); } class Rot13Test extendsPHPUnit_Framework_TestCase { /* […] */ public functiontest_N_Purely() { $this->assertEquals(‘$purely$', rot13(‘$cheryl$')); } } FAIL !

26. Test first ! (6b) functionrot13($text) { $str = ''; $len = strlen($text); for ($i = 0; $i < $len; $i++) { if (!ctype_alnum($text{$i})) { $str .= $text{$i}; } else { if (ctype_upper($text{$i})) { $delta = ord('A'); } else { $delta = ord('a'); } $str.= chr((ord($text{$i}) - $delta + 13) % 26 + $delta); } } return$str; } PASS !

27. Test-drivendevelopment RED GREEN REFACTOR

28. PHPUnit assertions Note: most assertions have a assertNotXXXX() counterpart.

29. Test status Do yourself and yourcolleaguesa favor and mark tests as skipped or incompletewhen relevant !

30. Anatomy of a unit test SETUP: Create the fixture EXERCISE: Execute the system under test (SUT) VERIFY: Check expectations (state mutations, output, invariants, etc.) TEAR DOWN: Clean the fixture

32. FULLY automated

33. Self-checking

34. Simple, robust

35. Expressive

36. Should not harm the developmentprocess in the long runTests, if usedincorrectly, canbedetrimental to a project

37. Principles of test automation 1) INDEPENDANCE: A test should not interactwithanother test (shared mutable state). 2) NO TEST CODE IN PRODUCTION: Ban if ($test). Don’teventhink about it. 3) ISOLATION: Each SUT must beindependant. State mutations duringexerciseshould onlyoccur in and by the SUT. 4) D.R.Y.: Do not repeatyourself. Valid for fixture setup as well as test overlap. 5) CLEAR INTENTIONS: A test shouldbe simple and clearlycommunicateits scope. 6) MINIMIZE UNTESTABLE CODE: Sorry, please replace minimize by eliminate. 7) TEST FIRST: Preventsmostsmells, ensureshighcoverage, providesimmediate feedback. 8) DO NOT TEST YOUR PRIVATES: The need to test a privatemethodis a symptom of a deeperproblem.

38. Exempligratia Symfony2’s routing component: https://github.com/symfony/symfony/blob/master/tests/Symfony/Tests/Component/Routing/Matcher/UrlMatcherTest.php Example of a feeble test (objectcreation code repeated), long test (testMatch). Symfony2’s DOM Crawler: https://github.com/symfony/symfony/blob/master/tests/Symfony/Tests/Component/DomCrawler/CrawlerTest.php Example of utility methods (at the bottom), @covers, SUT factorymethod (createTestCrawler). Symfony2’s HttpKernel component: https://github.com/symfony/symfony/blob/master/tests/Symfony/Tests/Component/HttpKernel/KernelTest.php Example of test doubles.

39. Resources The seminal book on unit testing. Written by Gerard Meszaros. ISBN-13: 978-0131495050