Legacy Code - Testing and Safe Refactoring

I can't test this code because it's legacy. I need to update the code to make it testable. How can I manage that, without breaking existing functionality? I'll need to write some tests, but... argh!

1. @maccath | Katy Ereira | #PHPUK20 Legacy Code. testing & safe refactoring
2. @maccath | Katy Ereira | #PHPUK20 What is legacy code? • Code that wasn’t written by you, just now • Code resulting from incorrect assumptions • Code built using unsupported technology • Code that isn’t tested
3. @maccath | Katy Ereira | #PHPUK20 What is refactoring? • Updating existing code without changing the application logic • Improving code structure • Usually done in small, incremental steps
4. @maccath | Katy Ereira | #PHPUK20 Why would I refactor? • Improve other developer’s understanding • Increase the application’s performance • Introduce new technology • Accommodate changes
5. @maccath | Katy Ereira | #PHPUK20 What is unit testing? • Verification that each individual ‘unit’ of an application works as intended • Units are the component parts of your application • Generally, each behaviour is a unit; likely to be contained within a function • Unit testing is not a substitute for other types of testing
6. @maccath | Katy Ereira | #PHPUK20 Why would I unit test? • Aid in the documentation of the system • To prevent regressions when changing code • To test integration with new technology • For validation of product requirements
7. @maccath | Katy Ereira | #PHPUK20 Paradox: can’t refactor untested code, but can’t test the code until it’s refactored.
8. @maccath | Katy Ereira | #PHPUK20 A solution 1. Rewrite the entire codebase 2. … 3. Profit! 1. Rewrite the entire codebase 2. … 3. Profit!
9. @maccath | Katy Ereira | #PHPUK20 A better solution 1. Perform just enough refactoring to make the code testable 2. Test the code 3. Lather, rinse, repeat. 4. Profit!
10. @maccath | Katy Ereira | #PHPUK20 Assumptions: you’re developing with PHP and you have access to a terminal with Composer.
11. @maccath | Katy Ereira | #PHPUK20 “ PHPUnit is a programmer-oriented testing framework for PHP. It is an instance of the xUnit architecture for unit testing frameworks. PHPUnit Reference: https:/ /phpunit.de/
12. @maccath | Katy Ereira | #ScotPHP19 I’m still on PHP version 5.6 / 7.0 / 7.1 ! PHPUnit Version PHP Version Requirement Supported Until 9 7.3, 7.4 Future release 8 7.2, 7.3, 7.4 February 5, 2021 7 7.1, 7.2, 7.3 February 7, 2020 6 7.0, 7.1, 7.2 February 8, 2019 5 5.6, 7.0, 7.1 February 2, 2018
13. @maccath | Katy Ereira | #ScotPHP19 Install via Composer: PHPUnit - installation $ composer require --dev phpunit/phpunit ^|version| $ ./vendor/bin/phpunit --version PHPUnit x.y.z by Sebastian Bergmann and contributors.
14. @maccath | Katy Ereira | #ScotPHP19 Anatomy of a unit test tests/ExampleTest.php class ExampleTest extends PHPUnit\Framework\TestCase { public function testSomeFunction() { $result = someFunction(); // Should return true $this->assertTrue($result); } }
15. @maccath | Katy Ereira | #ScotPHP19 Run your tests: Running the tests $ ./vendor/bin/phpunit tests PHPUnit 7.5.8 by Sebastian Bergmann and contributors. . 1 / 1 (100%) Time: 64 ms, Memory: 4.00 MB OK (1 test, 1 assertion)
16. @maccath | Katy Ereira | #PHPUK20 Mocking • Create test doubles • Verify the behaviour of your code • Isolate the system under test
17. @maccath | Katy Ereira | #PHPUK20 Mocking - Caution! DO: • Mock dependencies, when needed. • Be aware of tautological testing. DON’T: • Mock everything. • Mock the system under test.
18. @maccath | Katy Ereira | #PHPUK20 “ Mockery Mockery is a simple yet flexible PHP mock object framework for use in unit testing with PHPUnit, PHPSpec or any other testing framework. Reference: https:/ /github.com/mockery/mockery
19. @maccath | Katy Ereira | #PHPUK20 Install via Composer: $ composer require --dev mockery/mockery Mockery - Installation
20. @maccath | Katy Ereira | #PHPUK20 Mockery - Usage tests/ExampleTest.php class ExampleTest extends PHPUnit\Framework\TestCase { public function setUp(): void { $mockObject = Mockery::mock(Object::class); } }
21. @maccath | Katy Ereira | #PHPUK20 Mockery - Usage tests/ExampleTest.php class ExampleTest extends PHPUnit\Framework\TestCase { public function setUp(): void { $mockObject = Mockery::mock(Object::class); $mockObject->shouldReceive('method') // Expect that ‘method’ ->once() // should be called once ->andReturn(true); // and return true } }
22. @maccath | Katy Ereira | #PHPUK20 Mockery - Usage tests/ExampleTest.php class ExampleTest extends PHPUnit\Framework\TestCase { public function tearDown(): void { Mockery::close(); // Always close after running tests! } }
23. @maccath | Katy Ereira | #PHPUK20 Disclaimer: the following examples are deliberately simple.
24. @maccath | Katy Ereira | #PHPUK20 Tricky Test Scenario #1 Interfering Output
25. @maccath | Katy Ereira | #PHPUK20
26. @maccath | Katy Ereira | #PHPUK20 hillsAreAlive.php function yodel($tune = null) { if ($tune) { echo $tune; // The yodel is echoed back } else { echo 'Odl lay ee'; // A yodel begins } } A method that echoes
27. @maccath | Katy Ereira | #PHPUK20 A method that echoes tests/YodelTest.php class PrintedOutputTest extends PHPUnit\Framework\TestCase { public function testNewYodel() { yodel(); // Should echo ‘Odl lay ee’ } public function testEchoedYodel() { yodel('Lay hee hoo'); // Should echo ‘Lay hee hoo’ } }
28. @maccath | Katy Ereira | #PHPUK20 Run your tests: A method that echoes $ ./vendor/bin/phpunit tests PHPUnit 7.5.8 by Sebastian Bergmann and contributors. ROdl lay eeR 2 / 2 (100%)Lay hee hoo Time: 60 ms, Memory: 4.00 MB There were 2 risky tests
29. @maccath | Katy Ereira | #PHPUK20 • Prevent output being echoed to the test runner • Capture the output that would otherwise be echoed • Perform assertions on the captured output A method that echoes
30. @maccath | Katy Ereira | #PHPUK20 tests/YodelTest.php public function testNewYodel() { ob_start(); // Start capturing output. yodel(); } A method that echoes
31. @maccath | Katy Ereira | #PHPUK20 tests/YodelTest.php public function testNewYodel() { ob_start(); yodel(); ob_end_clean(); // Finish capturing output. } A method that echoes
32. @maccath | Katy Ereira | #PHPUK20 tests/YodelTest.php public function testNewYodel() { ob_start(); yodel(); $output = ob_get_contents(); // Get the output. ob_end_clean(); } A method that echoes
33. @maccath | Katy Ereira | #PHPUK20 tests/YodelTest.php public function testNewYodel() { ob_start(); yodel(); $output = ob_get_contents(); ob_end_clean(); $this->assertEquals('Odl lay ee', $output); // Success! } A method that echoes
34. @maccath | Katy Ereira | #PHPUK20 tests/YodelTest.php public function testEchoedYodel() { ob_start(); yodel('Lay hee hoo'); $output = ob_get_contents(); ob_end_clean(); $this->assertEquals('Lay hee hoo', $output); // Success! } A method that echoes
35. @maccath | Katy Ereira | #PHPUK20 Tricky Test Scenario #2 Static method calls
36. @maccath | Katy Ereira | #PHPUK20
37. @maccath | Katy Ereira | #PHPUK20 Vegeta.php function getPowerLevel() { $result = Goku::powerLevel(); // Goku’s power level is static. return $result > 9000 ? "It’s over 9000!" : "Suppressed."; } A static method call
38. @maccath | Katy Ereira | #PHPUK20 tests/PowerLevelTest.php class PowerLevelTest extends PHPUnit\Framework\TestCase { public function testUnder9000() { $result = getPowerLevel(); } public function testOver9000() { $result = getPowerLevel(); } } A static method call
39. @maccath | Katy Ereira | #PHPUK20 Goku.php class Goku { static function powerLevel() { return 5000; // Always returns 5000. } } A static method call
40. @maccath | Katy Ereira | #PHPUK20 tests/PowerLevelTest.php public function testUnder9000() { $result = getPowerLevel(); $this->assertEquals('Suppressed.', $result); // Success! } A static method call
41. @maccath | Katy Ereira | #PHPUK20 tests/PowerLevelTest.php public function testOver9000() { $result = getPowerLevel(); $this->assertEquals('It’s over 9000!', $result); // Failure. } A static method call
42. @maccath | Katy Ereira | #PHPUK20 A static method call • Create a new ‘mock’ of Goku, using a Mockery alias. • Set the return value of Goku::powerLevel to be 9001. • Run tests in separate processes.
43. @maccath | Katy Ereira | #PHPUK20 A static method call tests/PowerLevelTest.php public function testOver9000() { $superSaiyanGoku = Mockery::mock('alias:Goku'); // Mock Goku $result = getPowerLevel(); $this->assertEquals('It’s over 9000!', $result); // Failure. }
44. @maccath | Katy Ereira | #PHPUK20 A static method call tests/PowerLevelTest.php public function testOver9000() { $superSaiyanGoku = Mockery::mock('alias:Goku') ->shouldReceive('powerLevel') // Set Goku’s power level ->andReturn(9001); // to over 9000. . $result = getPowerLevel(); $this->assertEquals('It’s over 9000!', $result); // Failure. }
45. @maccath | Katy Ereira | #PHPUK20 A static method call tests/PowerLevelTest.php public function testOver9000() { // Goku is super saiyan! Mockery::mock('alias:Goku') ->shouldReceive('powerLevel') ->andReturn(9001); . $result = getPowerLevel(); $this->assertEquals('It’s over 9000!', $result); // Success! }
46. @maccath | Katy Ereira | #PHPUK20
47. @maccath | Katy Ereira | #PHPUK20 A static method call tests/PowerLevelTest.php /** * @runTestsInSeparateProcesses * @preserveGlobalState disabled */ class PowerLevelTest extends PHPUnit\Framework\TestCase { // ... }
48. @maccath | Katy Ereira | #PHPUK20 Tricky Test Scenario #3 Hard-coded dependencies
49. @maccath | Katy Ereira | #PHPUK20
50. @maccath | Katy Ereira | #PHPUK20 PessimistOrOptimist.php function getOutlook() { $weather = new WeatherForecast(); // A hard-coded dependency. $outlook = $weather->isSunny() ? "full" : "empty"; return "The glass is half $outlook."; } A hard-coded dependency
51. @maccath | Katy Ereira | #PHPUK20 WeatherForecast.php class WeatherForecast { static function isSunny() { return (bool) rand(0, 1); // Returns random true/false. } } A hard-coded dependency
52. @maccath | Katy Ereira | #PHPUK20 tests/OutlookTest.php class OutlookTest extends PHPUnit\Framework\TestCase { public function testHalfFull() { $result = getOutlook(); } public function testHalfEmpty() { $result = getOutlook(); } } A hard-coded dependency
53. @maccath | Katy Ereira | #PHPUK20 tests/OutlookTest.php public function testHalfFull() { $result = getOutlook(); $this->assertEquals('The glass is half full.', $result); } A hard-coded dependency
54. @maccath | Katy Ereira | #PHPUK20 tests/OutlookTest.php public function testHalfEmpty() { $result = getOutlook(); $this->assertEquals('The glass is half empty.', $result); } A hard-coded dependency
55. @maccath | Katy Ereira | #PHPUK20 Testing: hard-coded dependencies • Mock the WeatherForecast, using a Mockery override. • Set the return value of WeatherForecast::isSunny to be true or false. • Perform assertions based on mocked return values. • Run tests in separate processes.
56. @maccath | Katy Ereira | #PHPUK20 tests/OutlookTest.php public function testHalfFull() { $result = getOutlook(); $this->assertEquals('The glass is half full.', $result); } A hard-coded dependency
57. @maccath | Katy Ereira | #PHPUK20 tests/OutlookTest.php public function testHalfFull() { $mockForecast = Mockery::mock('overload:WeatherForecast'); // Overload $result = getOutlook(); $this->assertEquals('The glass is half full.', $result); } A hard-coded dependency
58. @maccath | Katy Ereira | #PHPUK20 tests/OutlookTest.php public function testHalfFull() { $mockForecast = Mockery::mock('overload:WeatherForecast') ->shouldReceive('isSunny'); // Set expectation $result = getOutlook(); $this->assertEquals('The glass is half full.', $result); // Success! } A hard-coded dependency
59. @maccath | Katy Ereira | #PHPUK20 tests/OutlookTest.php public function testHalfFull() { $mockForecast = Mockery::mock('overload:WeatherForecast') ->shouldReceive('isSunny') ->andReturn(true); // Force return value true $result = getOutlook(); $this->assertEquals('The glass is half full.', $result); // Success! } A hard-coded dependency
60. @maccath | Katy Ereira | #PHPUK20 tests/OutlookTest.php public function testHalfFull() { $mockForecast = Mockery::mock('overload:WeatherForecast') ->shouldReceive('isSunny') ->andReturn(true); // Force return value true $result = getOutlook(); $this->assertEquals('The glass is half full.', $result); // Success! } A hard-coded dependency
61. @maccath | Katy Ereira | #PHPUK20 tests/OutlookTest.php public function testHalfEmpty() { $mockForecast = Mockery::mock('overload:WeatherForecast') ->shouldReceive('isSunny') ->andReturn(false); // Force return value false $result = getOutlook(); $this->assertEquals('The glass is half empty.', $result); // Success! } A hard-coded dependency
62. @maccath | Katy Ereira | #PHPUK20 tests/OutlookTest.php public function testHalfEmpty() { $mockForecast = Mockery::mock('overload:WeatherForecast') ->shouldReceive('isSunny') ->andReturn(false); // Force return value false $result = getOutlook(); $this->assertEquals('The glass is half empty.', $result); // Success! } A hard-coded dependency
63. @maccath | Katy Ereira | #PHPUK20 tests/OutlookTest.php /** * @runTestsInSeparateProcesses * @preserveGlobalState disabled */ class OutlookTest extends PHPUnit\Framework\TestCase { // ... } A hard-coded dependency
64. @maccath | Katy Ereira | #PHPUK20 • Refactor the code to use an injected dependency. • Mock the dependency. • Inject the mocked dependency. • Remove @runTestsInSeparateProcesses annotation. Refactoring: hard-coded dependencies
65. @maccath | Katy Ereira | #PHPUK20 myLegacyCode.php function getOutlook() { $weather = new WeatherForecast(); $outlook = $weather->isSunny() ? "full" : "empty"; return "The glass is half $outlook."; } A hard-coded dependency
66. @maccath | Katy Ereira | #PHPUK20 myLegacyCode.php function getOutlook(WeatherForecast $weather = null) // Inject { $weather = new WeatherForecast(); $outlook = $weather->isSunny() ? "full" : "empty"; return "The glass is half $outlook."; } A hard-coded dependency
67. @maccath | Katy Ereira | #PHPUK20 myLegacyCode.php function getOutlook(WeatherForecast $weather = null) { $weather = $weather ?? new WeatherForecast(); // Use injected dependency $outlook = $weather->isSunny() ? "full" : "empty"; return "The glass is half $outlook."; } A hard-coded dependency
68. @maccath | Katy Ereira | #PHPUK20 tests/OutlookTest.php public function testHalfFull() { $mockForecast = Mockery::mock('overload:WeatherForecast') ->shouldReceive('isSunny') ->andReturn(true); $result = getOutlook(); $this->assertEquals('The glass is half full.', $result); // Success! } A hard-coded dependency
69. @maccath | Katy Ereira | #PHPUK20 tests/OutlookTest.php public function testHalfFull() { $mockForecast = Mockery::mock(WeatherForecast::class) // No overload! ->shouldReceive('isSunny') ->andReturn(true); $result = getOutlook(); $this->assertEquals('The glass is half full.', $result); // Success! } A hard-coded dependency
70. @maccath | Katy Ereira | #PHPUK20 tests/OutlookTest.php public function testHalfFull() { $mockForecast = Mockery::mock(WeatherForecast::class) ->shouldReceive('isSunny') ->andReturn(true); $result = getOutlook($mockForecast); // Inject! $this->assertEquals('The glass is half full.', $result); // Success! } A hard-coded dependency
71. @maccath | Katy Ereira | #PHPUK20 tests/OutlookTest.php /** * @runTestsInSeparateProcesses */ class OutlookTest extends PHPUnit\Framework\TestCase { // ... } A hard-coded dependency
72. @maccath | Katy Ereira | #PHPUK20 tests/OutlookTest.php /** * @runTestsInSeparateProcesses */ class OutlookTest extends PHPUnit\Framework\TestCase { // ... } A hard-coded dependency
73. @maccath | Katy Ereira | #PHPUK20 Tricky Test Scenario #4 Ungraceful exits
74. @maccath | Katy Ereira | #PHPUK20 Tricky Test Scenario #4 (a) Redirects
75. @maccath | Katy Ereira | #PHPUK20
76. @maccath | Katy Ereira | #PHPUK20 holyGrail.php function enterCaveOfCaerbannog(bool $killerRabbit = false) { if ($killerRabbit) { header('Location: http://www.montypython.com'); } return "Behold!"; } Redirections
77. @maccath | Katy Ereira | #PHPUK20 tests/CaveOfCaerbannogTest.php class EnterCaveOfCaerbannogTest extends PHPUnit\Framework\TestCase { public function testEnterSafely() { enterCaveOfCaerbannog(); } public function testRunAway() { enterCaveOfCaerbannog($killerRabbit = true); } } Redirections
78. @maccath | Katy Ereira | #PHPUK20 tests/CaveOfCaerbannogTest.php /** * @runTestsInSeparateProcesses */ class EnterCaveOfCaerbannogTest extends PHPUnit\Framework\TestCase { public function testEnterSafely() { … } public function testRunAway() { … } } Redirections
79. @maccath | Katy Ereira | #PHPUK20 tests/CaveOfCaerbannogTest.php public function testEnterSafely() { $result = enterCaveOfCaerbannog(); $this->assertEquals('Behold!', $result); // Success! } Redirections
80. @maccath | Katy Ereira | #PHPUK20 tests/CaveOfCaerbannogTest.php public function testRunAway() { $result = enterCaveOfCaerbannog($killerRabbit = true); $this->assertNotEquals('Behold!', $result); // Failure. } Redirections
81. @maccath | Katy Ereira | #PHPUK20 Refactoring: Redirections • Return/continue/break after (potentially) redirecting. or • Set redirection header as the very last step.
82. @maccath | Katy Ereira | #PHPUK20 holyGrail.php function enterCaveOfCaerbannog(bool $killerRabbit = false) { if ($killerRabbit) { header('Location: http://www.montypython.com'); return; // Go no further! } return "Behold!"; } Redirections
83. @maccath | Katy Ereira | #PHPUK20 holyGrail.php function enterCaveOfCaerbannog(bool $killerRabbit = false) { if (!$killerRabbit) { return "Behold!"; // Return early. } header('Location: http://www.montypython.com'); } Redirections
84. @maccath | Katy Ereira | #PHPUK20 tests/CaveOfCaerbannogTest.php public function testRunAway() { $result = enterCaveOfCaerbannog($killerRabbit = true); $this->assertEmpty($result); // Success! } Redirections
85. @maccath | Katy Ereira | #PHPUK20 Tricky Test Scenario #4 (b) Exiting
86. @maccath | Katy Ereira | #PHPUK20
87. @maccath | Katy Ereira | #PHPUK20 Brexit.php function brexit(bool $remainer = false) { if ($remainer) { return 'Bollocks to Brexit!'; } exit; } Exiting
88. @maccath | Katy Ereira | #PHPUK20 tests/BrexitTest.php class BrexitTest extends PHPUnit\Framework\TestCase { public function testBrexit() { $result = brexit(); } public function testRemainer() { $result = brexit($remainer = true); } } Exiting
89. @maccath | Katy Ereira | #PHPUK20 tests/BrexitTest.php public function testRemainer() { $result = brexit($remainer = true); $this->assertEquals('Bollocks to Brexit!', $result); // Success! } Exiting
90. @maccath | Katy Ereira | #PHPUK20 tests/BrexitTest.php public function testBrexit() { $result = brexit(); $this->assertEmpty($result); // We never get here. } Exiting
91. @maccath | Katy Ereira | #PHPUK20 Refactoring: Exiting • Create a wrapper around the exit functionality. • Inject the exit wrapper. • Safely refactor to use the exit wrapper. • Mock the exit wrapper.
92. @maccath | Katy Ereira | #PHPUK20 Boris.php class Boris { public function getBrexitDone() { exit; // Completely exits. } } Exiting
93. @maccath | Katy Ereira | #PHPUK20 Brexit.php function brexit(bool $remainer, Boris $boris = null) // Inject { if ($remainer) { … } exit; } Exiting
94. @maccath | Katy Ereira | #PHPUK20 Brexit.php function brexit(bool $remainer, Boris $boris = null) { $boris = $boris ?? new Boris(); // Set default. if ($remainer) { … } exit; } Exiting
95. @maccath | Katy Ereira | #PHPUK20 Brexit.php function brexit(bool $remainer, Boris $boris = null) { $boris = $boris ?? new Boris(); if ($remainer) { … } $boris->getBrexitDone(); // Be Boris. } Exiting
96. @maccath | Katy Ereira | #PHPUK20 tests/BrexitTest.php public function testBrexit() { $mockBoris = Mockery::mock(Boris::class); // Mock Boris. $result = brexit(); $this->assertEmpty($result); // Failure. } Exiting
97. @maccath | Katy Ereira | #PHPUK20 tests/BrexitTest.php public function testBrexit() { $mockBoris = Mockery::mock(Boris::class) ->shouldIgnoreMissing(); // Do nothing... $result = brexit(); $this->assertEmpty($result); // Failure. } Exiting
98. @maccath | Katy Ereira | #PHPUK20 tests/BrexitTest.php public function testBrexit() { $mockBoris = Mockery::mock(Boris::class) ->shouldIgnoreMissing(); $result = brexit($remainer = false, $mockBoris); // Use Boris. $this->assertEmpty($result); // Success! } Exiting
99. @maccath | Katy Ereira | #PHPUK20 tests/BrexitTest.php public function testBrexit() { $mockBoris = Mockery::mock(Boris::class) ->shouldIgnoreMissing(); $result = brexit($remainer = false, $mockBoris); $this->assertEmpty($result); // Success! } Exiting
100. @maccath | Katy Ereira | #PHPUK20 Tricky Test Scenario #5 Filesystem interaction
101. @maccath | Katy Ereira | #PHPUK20
102. @maccath | Katy Ereira | #PHPUK20 HitCounter.php function countHit() { $count = file_get_contents(__DIR__ . '/hit_counter.txt'); file_put_contents(__DIR__ . '/hit_counter.txt', ++$count); } Updating a file
103. @maccath | Katy Ereira | #PHPUK20 tests/HitCounterTest.php class HitCounterTest extends PHPUnit\Framework\TestCase { public function testCountsHit() { countHit(); } } Updating a file
104. @maccath | Katy Ereira | #PHPUK20 tests/HitCounterTest.php public function testCountsHit() { $hitCounterFile = __DIR__ . '/../hit_counter.txt'; $countBefore = file_get_contents($hitCounterFile); countHit(); $countAfter = file_get_contents($hitCounterFile); $this->assertEquals($countBefore++, $countAfter); // Success! } Updating a file
105. @maccath | Katy Ereira | #PHPUK20 Refactoring: Updating a file • Inject the filename. • Create a test double hit counter file. • Reset the file contents after each test.
106. @maccath | Katy Ereira | #PHPUK20 HitCounter.php function countHit() { $count = file_get_contents(__DIR__ . '/hit_counter.txt'); file_put_contents(__DIR__ . '/hit_counter.txt', ++$count); } Updating a file
107. @maccath | Katy Ereira | #PHPUK20 HitCounter.php function countHit($file = __DIR__ . '/hit_counter.txt') // Inject $file { $count = file_get_contents(__DIR__ . '/hit_counter.txt'); file_put_contents(__DIR__ . '/hit_counter.txt', ++$count); } Updating a file
108. @maccath | Katy Ereira | #PHPUK20 HitCounter.php function countHit($file = __DIR__ . '/hit_counter.txt') // Inject $file { $count = file_get_contents($file); // Use $file file_put_contents($file, ++$count); // Use $file } Updating a file
109. @maccath | Katy Ereira | #PHPUK20 tests/Unit/HitCounterTest.php public function testCountsHit() { $hitCounterFile = __DIR__ . '/hit_counter.txt'; $countBefore = file_get_contents($hitCounterFile); countHit(); $countAfter = file_get_contents($hitCounterFile); $this->assertEquals($countBefore++, $countAfter); } Updating a file
110. @maccath | Katy Ereira | #PHPUK20 tests/HitCounterTest.php public function testCountsHit() { $hitCounterFile = __DIR__ . '/test_hit_counter.txt'; // Test file! $countBefore = file_get_contents($hitCounterFile); countHit(); $countAfter = file_get_contents($hitCounterFile); $this->assertEquals($countBefore++, $countAfter); } Updating a file
111. @maccath | Katy Ereira | #PHPUK20 tests/HitCounterTest.php public function testCountsHit() { $hitCounterFile = __DIR__ . '/test_hit_counter.txt'; $countBefore = file_get_contents($hitCounterFile); countHit($hitCounterFile); // Use test hit counter file. $countAfter = file_get_contents($hitCounterFile); $this->assertEquals($countBefore++, $countAfter); } Updating a file
112. @maccath | Katy Ereira | #PHPUK20 tests/HitCounterTest.php public function tearDown(): void { $hitCounterFile = __DIR__ . '/test_hit_counter.txt'; file_put_contents($hitCounterFile, 0); // Reset counter. } Updating a file
113. @maccath | Katy Ereira | #PHPUK20 “ vfsStream is a stream wrapper for a virtual file system that may be helpful in unit tests to mock the real file system. It can be used with any unit test framework, like PHPUnit or SimpleTest. Fake filesystem Reference: http:/ /vfs.bovigo.org/
114. @maccath | Katy Ereira | #PHPUK20 tests/HitCounterTest.php public function testCountsHit() { $hitCounterFile = __DIR__ . '/test_hit_counter.txt'; $countBefore = file_get_contents($hitCounterFile); countHit($hitCounterFile); $countAfter = file_get_contents($hitCounterFile); $this->assertEquals($countBefore++, $countAfter); } Fake filesystem
115. @maccath | Katy Ereira | #PHPUK20 tests/HitCounterTest.php public function testCountsHit() { $vfs = vfsStream::setup(); $hitCounterFile = vfsStream::newFile('test_hit_counter.txt') ->at($vfs) ->setContent('0'); countHit($hitCounterFile->url()); $this->assertEquals(1, $hitCounterFile->getContent()); } Fake filesystem
116. @maccath | Katy Ereira | #PHPUK20 tests/HitCounterTest.php public function tearDown(): void { $hitCounterFile = __DIR__ . '/test_hit_counter.txt'; file_put_contents($hitCounterFile, 0); // Reset counter. } Fake filesystem
117. @maccath | Katy Ereira | #PHPUK20 tests/HitCounterTest.php public function tearDown(): void { $hitCounterFile = __DIR__ . '/test_hit_counter.txt'; file_put_contents($hitCounterFile, 0); // Reset counter. } Fake filesystem
118. @maccath | Katy Ereira | #PHPUK20 Tricky Test Scenario #6 Spaghetti code
119. @maccath | Katy Ereira | #PHPUK20
120. @maccath | Katy Ereira | #PHPUK20 Spaghetti code Bolognese.php class Bolognese { private $eaten; private $parmesan; public function __construct(bool $eaten = false) { … } public function eat() { … } public function isEaten(): bool { … } }
121. @maccath | Katy Ereira | #PHPUK20 Spaghetti code Bolognese.php public function eat() { if ($this->eaten) return; // Can’t eat twice! if (!$this->parmesan || !$this->parmesan->isEaten()) { $this->parmesan = new Parmesan(); // Must always have parmesan. } (new GarlicBread())->eat(); // Gotta have garlic bread. $this->parmesan->eat(); $this->eaten = true; }
122. @maccath | Katy Ereira | #PHPUK20 tests/BologneseTest.php class BologneseTest extends PHPUnit\Framework\TestCase { public function testEat() { $bolognese = new Bolognese(); $bolognese->eat(); } } Spaghetti code
123. @maccath | Katy Ereira | #PHPUK20 tests/BologneseTest.php public function testEat() { $bolognese = new Bolognese(); $bolognese->eat(); $this->assertTrue($bolognese->isEaten()); } Spaghetti code
124. @maccath | Katy Ereira | #PHPUK20 Testing: Spaghetti Code • Use @covers annotation to isolate unit under test • Create reusable expectations: ◦ to illustrate different scenarios ◦ to define alternate process branches
125. @maccath | Katy Ereira | #PHPUK20 tests/BologneseTest.php /** * @covers Bolognese */ public function testEat() { $bolognese = new Bolognese(); $bolognese->eat(); $this->assertTrue($bolognese->isEaten()); } Testing: Spaghetti Code
126. @maccath | Katy Ereira | #PHPUK20 tests/BologneseTest.php public function testEatDevouredBolognese() { … } public function testEatUneatenBolognese() { … } Testing: Spaghetti Code
127. @maccath | Katy Ereira | #PHPUK20 tests/BologneseTest.php private function eatenBolognese() { return new Bolognese($eaten = true); } private function uneatenBolognese() { return new Bolognese($eaten = false); } Testing: Spaghetti Code
128. @maccath | Katy Ereira | #PHPUK20 tests/BologneseTest.php private function expectGarlicBreadToBeEaten() { $garlicBread = Mockery::mock('overload:GarlicBread'); return $garlicBread->shouldReceive('eat'); // Return expectation. } Testing: Spaghetti Code
129. @maccath | Katy Ereira | #PHPUK20 tests/BologneseTest.php public function testEatDevouredBolognese() { $this->expectGarlicBreadToBeEaten()->never(); $this->eatenBolognese()->eat(); } public function testEatUneatenBolognese() { $this->expectGarlicBreadToBeEaten()->once(); $this->uneatenBolognese()->eat(); } Testing: Spaghetti Code
130. @maccath | Katy Ereira | #PHPUK20 Tricky Test Scenario #7 Private methods
131. @maccath | Katy Ereira | #PHPUK20
132. @maccath | Katy Ereira | #PHPUK20 Private methods MCHammer.php class MCHammer { public function stop() { return $this->cantTouchThis(); } private function cantTouchThis() { return 'hammertime'; } }
133. @maccath | Katy Ereira | #PHPUK20 Private methods tests/MCHammerTest.php class MCHammerTest extends PHPUnit\Framework\TestCase { public function testCantTouchThis() { $mcHammer = new MCHammer(); $result = $mcHammer->cantTouchThis(); // Error; private method! $this->assertEquals('hammertime', $result); } }
134. @maccath | Katy Ereira | #PHPUK20 Private methods • Don’t test private methods. • Test the public methods that use private methods. • Private methods represent implementation details. • Private methods should remain invisible.
135. @maccath | Katy Ereira | #PHPUK20 Private methods tests/MCHammerTest.php class MCHammerTest extends PHPUnit\Framework\TestCase { public function testCantTouchThis() { $mcHammer = new MCHammer(); $result = $mcHammer->stop(); // Public method! $this->assertEquals('hammertime', $result); } }
136. @maccath | Katy Ereira | #PHPUK20 Private methods tests/MCHammerTest.php class MCHammerTest extends PHPUnit\Framework\TestCase { public function testCantTouchThis() { $mcHammer = new MCHammer(); $result = $mcHammer->stop(); $this->assertEquals('hammertime', $result); // Success! } }
137. @maccath | Katy Ereira | #PHPUK20 Time for a recap... • Interfering output • Static methods • Hard-coded dependencies • Ungraceful exits • Filesystem interaction • Spaghetti code • Private methods
138. @maccath | Katy Ereira | #PHPUK20 https://joind.in/talk/585f1