Legacy Code - Testing and Safe Refactoring - Laravel Live UK 2019

Legacy Code - Testing and Safe Refactoring - Laravel Live UK 2019

"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!"

We've all been there! In this talk we'll look at safe ways to refactor 'untestable' code to make it testable - without breaking any existing functionality. Promise! Then, further changes will be much easier!

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Katy Ereira

June 11, 2019
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  1. @maccath | Katy Ereira | #LaravelLive Legacy Code. testing &

    safe refactoring
  2. @maccath | Katy Ereira | #LaravelLive 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 | #LaravelLive What is refactoring? •

    Changing existing code without changing the application logic • Improving code structure • Usually done in small, incremental steps
  4. @maccath | Katy Ereira | #LaravelLive Why would I refactor?

    • Improve other developer’s understanding • Increase the application’s performance • Introduce new technology • Accommodate changes in product requirements
  5. @maccath | Katy Ereira | #LaravelLive 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 | #LaravelLive Why would I unit

    test? • Aid in the documentation of the system • To prevent regressions when adding/changing code • To test integration with new technology • For validation of product requirements
  7. @maccath | Katy Ereira | #LaravelLive Paradox: can’t refactor untested

    code, but can’t test the code until it’s refactored.
  8. @maccath | Katy Ereira | #LaravelLive A solution 1. Rewrite

    the entire codebase 2. … 3. Profit! 1. Rewrite the entire codebase 2. … 3. Profit!
  9. @maccath | Katy Ereira | #LaravelLive A better solution 1.

    Perform just enough refactoring to make the code testable 2. Test the code 3. Refactor the code further 4. Profit!
  10. @maccath | Katy Ereira | #LaravelLive Assumptions: you’re developing with

    PHP and you have access to a terminal with Composer.
  11. @maccath | Katy Ereira | #LaravelLive “ 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 | #LaravelLive Create a test using

    Artisan: Anatomy of a unit test $ php artisan make:test ExampleTest --unit
  13. @maccath | Katy Ereira | #LaravelLive Anatomy of a unit

    test tests/Unit/ExampleTest.php namespace Tests\Unit; use Tests\TestCase; class ExampleTest extends TestCase { public function testSomeFunction() { $result = someFunction(); // Should return true $this->assertTrue($result); } }
  14. @maccath | Katy Ereira | #LaravelLive Run your tests: Running

    the tests $ ./vendor/bin/phpunit tests/Unit PHPUnit <version> by Sebastian Bergmann and contributors. . 1 / 1 (100%) Time: 64 ms, Memory: 4.00 MB OK (1 test, 1 assertion)
  15. @maccath | Katy Ereira | #LaravelLive “ 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
  16. @maccath | Katy Ereira | #LaravelLive Install via Composer: $

    composer require --dev mockery/mockery Mockery - Installation
  17. @maccath | Katy Ereira | #LaravelLive Mockery - Usage tests/Unit/ExampleTest.php

    class ExampleTest extends PHPUnit\Framework\TestCase { public function setUp() { $mockObject = Mockery::mock(Object::class); // Mock object. } }
  18. @maccath | Katy Ereira | #LaravelLive Mockery - Usage tests/Unit/ExampleTest.php

    class ExampleTest extends PHPUnit\Framework\TestCase { public function setUp() { $mockObject = Mockery::mock(Object::class); $mockObject->shouldReceive('method') // Expectation ->once() // Method called once ->andReturn(true); // Method returns true } } tests/Unit/ExampleTest.php
  19. @maccath | Katy Ereira | #LaravelLive Mockery - Usage tests/Unit/ExampleTest.php

    class ExampleTest extends PHPUnit\Framework\TestCase { public function tearDown() { Mockery::close(); // Always close after running tests! } } tests/Unit/ExampleTest.php
  20. @maccath | Katy Ereira | #LaravelLive Mockery - Usage tests/Unit/ExampleTest.php

    use Illuminate\Foundation\Testing\TestCase as BaseTestCase; class ExampleTest extends BaseTestCase { }
  21. @maccath | Katy Ereira | #LaravelLive Mocking - Caution! DO:

    • Mock dependencies, when needed. • Be aware of tautological testing. DON’T: • Mock everything. • Mock the system under test.
  22. @maccath | Katy Ereira | #LaravelLive Disclaimer: the following examples

    are deliberately simple.
  23. @maccath | Katy Ereira | #LaravelLive Tricky Test Scenario #1

    Output interference
  24. @maccath | Katy Ereira | #LaravelLive A method that echoes

  25. @maccath | Katy Ereira | #LaravelLive myLegacyCode.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
  26. @maccath | Katy Ereira | #LaravelLive A method that echoes

    tests/Unit/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’ } }
  27. @maccath | Katy Ereira | #LaravelLive 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
  28. @maccath | Katy Ereira | #LaravelLive • 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
  29. @maccath | Katy Ereira | #LaravelLive tests/Unit/YodelTest.php public function testNewYodel()

    { ob_start(); // Start capturing output. yodel(); } A method that echoes
  30. @maccath | Katy Ereira | #LaravelLive tests/Unit/YodelTest.php public function testNewYodel()

    { ob_start(); yodel(); ob_end_clean(); // Finish capturing output. } A method that echoes
  31. @maccath | Katy Ereira | #LaravelLive tests/Unit/YodelTest.php public function testNewYodel()

    { ob_start(); yodel(); $output = ob_get_contents(); // Get the output. ob_end_clean(); } A method that echoes
  32. @maccath | Katy Ereira | #LaravelLive tests/Unit/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
  33. @maccath | Katy Ereira | #LaravelLive tests/Unit/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
  34. @maccath | Katy Ereira | #LaravelLive Tricky Test Scenario #2

    Hard-coded dependencies
  35. @maccath | Katy Ereira | #LaravelLive A static method call

  36. @maccath | Katy Ereira | #LaravelLive myLegacyCode.php function getPowerLevel() {

    $result = Goku::powerLevel(); // Goku’s power level is static. return $result > 9000 ? "It’s over 9000!" : "Suppressed."; } A static method call
  37. @maccath | Katy Ereira | #LaravelLive tests/Unit/PowerLevelTest.php class PowerLevelTest extends

    PHPUnit\Framework\TestCase { public function testUnder9000() { $result = getPowerLevel(); } public function testOver9000() { $result = getPowerLevel(); } } A static method call
  38. @maccath | Katy Ereira | #LaravelLive Goku.php class Goku {

    static function powerLevel() { return 5000; // Always returns 5000. } } A static method call
  39. @maccath | Katy Ereira | #LaravelLive tests/Unit/PowerLevelTest.php public function testUnder9000()

    { $result = getPowerLevel(); $this->assertEquals('Suppressed.', $result); // Success! } A static method call
  40. @maccath | Katy Ereira | #LaravelLive tests/Unit/PowerLevelTest.php public function testOver9000()

    { $result = getPowerLevel(); $this->assertEquals('It’s over 9000!', $result); // Failure. } A static method call
  41. @maccath | Katy Ereira | #LaravelLive 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.
  42. @maccath | Katy Ereira | #LaravelLive A static method call

    tests/Unit/PowerLevelTest.php public function testOver9000() { $superSaiyanGoku = Mockery::mock('alias:Goku'); // Mock Goku $result = getPowerLevel(); $this->assertEquals('It’s over 9000!', $result); // Failure. }
  43. @maccath | Katy Ereira | #LaravelLive A static method call

    tests/Unit/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. }
  44. @maccath | Katy Ereira | #LaravelLive A static method call

    tests/Unit/PowerLevelTest.php /** * @runTestsInSeparateProcesses */ class PowerLevelTest extends PHPUnit\Framework\TestCase { // ... }
  45. @maccath | Katy Ereira | #LaravelLive A static method call

    tests/Unit/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 | #LaravelLive “ A static method

    call - via a Facade Unlike traditional static method calls, facades may be mocked. This provides a great advantage over traditional static methods and grants you the same testability you would have if you were using dependency injection. Reference: https:/ /laravel.com/docs/5.8/mocking#mocking-facades
  47. @maccath | Katy Ereira | #LaravelLive A static method call

    - via a Facade tests/Unit/PowerLevelTest.php public function testOver9000() { $superSaiyanGoku = Mockery::mock('alias:Goku') ->shouldReceive('powerLevel') ->andReturn(9001); . $result = getPowerLevel(); $this->assertEquals('It’s over 9000!', $result); // Success! }
  48. @maccath | Katy Ereira | #LaravelLive A static method call

    - via a Facade tests/Unit/PowerLevelTest.php public function testOver9000() { // Goku is super saiyan! Goku::shouldReceive('powerLevel') ->andReturn(9001); . $result = getPowerLevel(); $this->assertEquals('It’s over 9000!', $result); // Success! }
  49. @maccath | Katy Ereira | #LaravelLive A static method call

    - via a Facade tests/Unit/PowerLevelTest.php /** * @runTestsInSeparateProcesses */ class PowerLevelTest extends TestCase { // ... }
  50. @maccath | Katy Ereira | #LaravelLive A static method call

    - via a Facade tests/Unit/PowerLevelTest.php /** * @runTestsInSeparateProcesses */ class PowerLevelTest extends TestCase { // ... }
  51. @maccath | Katy Ereira | #LaravelLive A hard-coded dependency

  52. @maccath | Katy Ereira | #LaravelLive myLegacyCode.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
  53. @maccath | Katy Ereira | #LaravelLive WeatherForecast.php class WeatherForecast {

    static function isSunny() { return (bool) rand(0, 1); // Returns random true/false. } } A hard-coded dependency
  54. @maccath | Katy Ereira | #LaravelLive tests/Unit/OutlookTest.php class OutlookTest extends

    PHPUnit\Framework\TestCase { public function testHalfFull() { $result = getOutlook(); } public function testHalfEmpty() { $result = getOutlook(); } } A hard-coded dependency
  55. @maccath | Katy Ereira | #LaravelLive tests/Unit/OutlookTest.php public function testHalfFull()

    { $result = getOutlook(); $this->assertEquals('The glass is half full.', $result); } A hard-coded dependency
  56. @maccath | Katy Ereira | #LaravelLive tests/Unit/OutlookTest.php public function testHalfEmpty()

    { $result = getOutlook(); $this->assertEquals('The glass is half empty.', $result); } A hard-coded dependency
  57. @maccath | Katy Ereira | #LaravelLive A hard-coded dependency •

    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.
  58. @maccath | Katy Ereira | #LaravelLive tests/Unit/OutlookTest.php public function testHalfFull()

    { $result = getOutlook(); $this->assertEquals('The glass is half full.', $result); } A hard-coded dependency
  59. @maccath | Katy Ereira | #LaravelLive tests/Unit/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
  60. @maccath | Katy Ereira | #LaravelLive tests/Unit/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
  61. @maccath | Katy Ereira | #LaravelLive tests/Unit/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
  62. @maccath | Katy Ereira | #LaravelLive tests/Unit/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 | #LaravelLive tests/Unit/OutlookTest.php /** * @runTestsInSeparateProcesses

    */ class OutlookTest extends PHPUnit\Framework\TestCase { // ... } A hard-coded dependency
  64. @maccath | Katy Ereira | #LaravelLive • 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 | #LaravelLive 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 | #LaravelLive 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 | #LaravelLive 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 | #LaravelLive 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 | #LaravelLive 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 | #LaravelLive 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 | #LaravelLive tests/Unit/OutlookTest.php /** * @runTestsInSeparateProcesses

    */ class OutlookTest extends PHPUnit\Framework\TestCase { // ... } A hard-coded dependency
  72. @maccath | Katy Ereira | #LaravelLive tests/Unit/OutlookTest.php /** * @runTestsInSeparateProcesses

    */ class OutlookTest extends PHPUnit\Framework\TestCase { // ... } A hard-coded dependency
  73. @maccath | Katy Ereira | #LaravelLive Tricky Test Scenario #3

    Ungraceful exits
  74. @maccath | Katy Ereira | #LaravelLive Redirections

  75. @maccath | Katy Ereira | #LaravelLive myLegacyCode.php function getMeOutOfHere(bool $imACelebrity

    = false) { if ($imACelebrity) { header('Location: http://google.com'); } return "Nope!"; } Redirections
  76. @maccath | Katy Ereira | #LaravelLive tests/Unit/GetMeOutTest.php class GetMeOutTest extends

    PHPUnit\Framework\TestCase { public function testLeaveMeHere() { getMeOutOfHere(); } public function testGetMeOut() { getMeOutOfHere($imACelebrity = true); } } Redirections
  77. @maccath | Katy Ereira | #LaravelLive tests/Unit/GetMeOutTest.php /** * @runTestsInSeparateProcesses

    */ class GetMeOutTest extends PHPUnit\Framework\TestCase { public function testLeaveMeHere() { … } public function testGetMeOut() { … } } Redirections
  78. @maccath | Katy Ereira | #LaravelLive tests/Unit/GetMeOutTest.php public function testLeaveMeHere()

    { $result = getMeOutOfHere(); $this->assertEquals('Nope!', $result); // Success! } Redirections
  79. @maccath | Katy Ereira | #LaravelLive tests/Unit/GetMeOutTest.php public function testGetMeOut()

    { $result = getMeOutOfHere($imACelebrity = true); $this->assertNotEquals('Nope!', $result); // Failure. } Redirections
  80. @maccath | Katy Ereira | #LaravelLive Refactoring: Redirections • Return/continue/break

    after (potentially) redirecting. or • Set redirection header as the very last step.
  81. @maccath | Katy Ereira | #LaravelLive myLegacyCode.php function getMeOutOfHere(bool $imACelebrity

    = false) { if ($imACelebrity) { header('Location: http://google.com'); return; // Don’t go any further! } return "Nope!"; } Redirections
  82. @maccath | Katy Ereira | #LaravelLive myLegacyCode.php function getMeOutOfHere(bool $imACelebrity

    = false) { if (!$imACelebrity) { return "Nope!"; // Return early. } header('Location: http://google.com'); } Redirections
  83. @maccath | Katy Ereira | #LaravelLive tests/Unit/GetMeOutTest.php public function testGetMeOut()

    { $result = getMeOutOfHere($imACelebrity = true); $this->assertNotEquals('Nope!', $result); // Success! } Redirections
  84. @maccath | Katy Ereira | #LaravelLive Exiting

  85. @maccath | Katy Ereira | #LaravelLive myLegacyCode.php function brexit(bool $remoaner

    = false) { if ($remoaner) { return 'People’s vote!'; } exit; } Exiting
  86. @maccath | Katy Ereira | #LaravelLive tests/Unit/BrexitTest.php class BrexitTest extends

    PHPUnit\Framework\TestCase { public function testBrexit() { $result = brexit(); } public function testRemoaner() { $result = brexit($remoaner = true); } } Exiting
  87. @maccath | Katy Ereira | #LaravelLive tests/Unit/BrexitTest.php public function testRemoaner()

    { $result = brexit($remoaner = true); $this->assertEquals('People’s vote!', $result); // Success! } Exiting
  88. @maccath | Katy Ereira | #LaravelLive tests/Unit/BrexitTest.php public function testBrexit()

    { $result = brexit(); $this->assertEmpty($result); // Never gets here. } Exiting
  89. @maccath | Katy Ereira | #LaravelLive Refactoring: Exiting • Create

    a wrapper around the exit functionality. • Inject the exit wrapper. • Safely refactor to use the exit wrapper. • Mock the exit wrapper.
  90. @maccath | Katy Ereira | #LaravelLive BrexitUtility.php class BrexitUtility {

    public function brexitMeansBrexit() { exit; // Completely exits. } } Exiting
  91. @maccath | Katy Ereira | #LaravelLive myLegacyCode.php function brexit(bool $remoaner,

    BrexitUtility $brexitUtil = null) // Inject { if ($remoaner) { … } exit; } Exiting
  92. @maccath | Katy Ereira | #LaravelLive myLegacyCode.php function brexit(bool $remoaner,

    BrexitUtility $brexitUtil = null) { $brexitUtil = $brexitUtil ?? new BrexitUtility(); // Set default. if ($remoaner) { … } exit; } Exiting
  93. @maccath | Katy Ereira | #LaravelLive myLegacyCode.php function brexit(bool $remoaner,

    BrexitUtility $brexitUtil = null) { $brexitUtil = $brexitUtil ?? new BrexitUtility(); if ($remoaner) { … } $brexitUtil->brexitMeansBrexit(); // Use the brexit utility. } Exiting
  94. @maccath | Katy Ereira | #LaravelLive tests/Unit/BrexitTest.php public function testBrexit()

    { $mockBrexitUtil = Mockery::mock(BrexitUtility::class); // Mock Brexit util $result = brexit(); $this->assertNotEquals('People’s vote!', $result); // Failure. } Exiting
  95. @maccath | Katy Ereira | #LaravelLive tests/Unit/BrexitTest.php public function testBrexit()

    { $mockBrexitUtil = Mockery::mock(BrexitUtility::class) ->shouldIgnoreMissing(); // Do nothing... $result = brexit(); $this->assertNotEquals('People’s vote!', $result); // Failure. } Exiting
  96. @maccath | Katy Ereira | #LaravelLive tests/Unit/BrexitTest.php public function testBrexit()

    { $mockBrexitUtil = Mockery::mock(BrexitUtility::class) ->shouldIgnoreMissing(); $result = brexit($remoaner = false, $mockBrexitUtil); // Use it. $this->assertNotEquals('People’s vote!', $result); // Success! } Exiting
  97. @maccath | Katy Ereira | #LaravelLive tests/Unit/BrexitTest.php public function testBrexit()

    { $mockBrexitUtil = Mockery::mock(BrexitUtility::class) ->shouldIgnoreMissing(); $result = brexit($remoaner = false, $mockBrexitUtil); $this->assertNotEquals('People’s vote!', $result); // Success! } Exiting
  98. @maccath | Katy Ereira | #LaravelLive Tricky Test Scenario #4

    The filesystem
  99. @maccath | Katy Ereira | #LaravelLive Filesystem

  100. @maccath | Katy Ereira | #LaravelLive myLegacyCode.php function countHit() {

    $count = file_get_contents(__DIR__ . '/hit_counter.txt'); file_put_contents(__DIR__ . '/hit_counter.txt', ++$count); } Updating a file
  101. @maccath | Katy Ereira | #LaravelLive tests/Unit/HitCounterTest.php class HitCounterTest extends

    PHPUnit\Framework\TestCase { public function testCountsHit() { countHit(); } } Updating a file
  102. @maccath | Katy Ereira | #LaravelLive 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); // Success! } Updating a file
  103. @maccath | Katy Ereira | #LaravelLive Refactoring: Updating a file

    • Inject the filename. • Create a test hit counter file. • Reset the file contents after each test.
  104. @maccath | Katy Ereira | #LaravelLive myLegacyCode.php function countHit() {

    $count = file_get_contents(__DIR__ . '/hit_counter.txt'); file_put_contents(__DIR__ . '/hit_counter.txt', ++$count); } Updating a file
  105. @maccath | Katy Ereira | #LaravelLive myLegacyCode.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
  106. @maccath | Katy Ereira | #LaravelLive myLegacyCode.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
  107. @maccath | Katy Ereira | #LaravelLive 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
  108. @maccath | Katy Ereira | #LaravelLive tests/Unit/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
  109. @maccath | Katy Ereira | #LaravelLive tests/Unit/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
  110. @maccath | Katy Ereira | #LaravelLive tests/Unit/HitCounterTest.php public function tearDown()

    { $hitCounterFile = __DIR__ . '/test_hit_counter.txt'; file_put_contents($hitCounterFile, 0); // Reset counter. } Updating a file
  111. @maccath | Katy Ereira | #LaravelLive “ 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/
  112. @maccath | Katy Ereira | #LaravelLive tests/Unit/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
  113. @maccath | Katy Ereira | #LaravelLive tests/Unit/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
  114. @maccath | Katy Ereira | #LaravelLive tests/Unit/HitCounterTest.php public function tearDown()

    { $hitCounterFile = __DIR__ . '/test_hit_counter.txt'; file_put_contents($hitCounterFile, 0); // Reset counter. } Fake filesystem
  115. @maccath | Katy Ereira | #LaravelLive tests/Unit/HitCounterTest.php public function tearDown()

    { $hitCounterFile = __DIR__ . '/test_hit_counter.txt'; file_put_contents($hitCounterFile, 0); // Reset counter. } Fake filesystem
  116. @maccath | Katy Ereira | #LaravelLive Tricky Test Scenario #5

    Spaghetti code
  117. @maccath | Katy Ereira | #LaravelLive Spaghetti code

  118. @maccath | Katy Ereira | #LaravelLive Spaghetti code src\Bolognese.php class

    Bolognese { private $eaten; private $parmesan; public function __construct(bool $eaten = false) { … } public function eat() { … } public function isEaten(): bool { … } }
  119. @maccath | Katy Ereira | #LaravelLive Spaghetti code src\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; }
  120. @maccath | Katy Ereira | #LaravelLive tests/Unit/BologneseTest.php class BologneseTest extends

    PHPUnit\Framework\TestCase { public function testEat() { $bolognese = new Bolognese(); $bolognese->eat(); } } Spaghetti code
  121. @maccath | Katy Ereira | #LaravelLive tests/Unit/BologneseTest.php public function testEat()

    { $bolognese = new Bolognese(); $bolognese->eat(); $this->assertTrue($bolognese->isEaten()); } Spaghetti code
  122. @maccath | Katy Ereira | #LaravelLive Testing: Spaghetti Code •

    Use @covers annotation to isolate unit under test • Create reusable expectations: ◦ to illustrate different scenarios ◦ to define alternate process branches
  123. @maccath | Katy Ereira | #LaravelLive tests/Unit/BologneseTest.php /** * @covers

    Bolognese */ public function testEat() { $bolognese = new Bolognese(); $bolognese->eat(); $this->assertTrue($bolognese->isEaten()); } Testing: Spaghetti Code
  124. @maccath | Katy Ereira | #LaravelLive tests/Unit/BologneseTest.php public function testEatDevouredBolognese()

    { … } public function testEatUneatenBolognese() { … } Testing: Spaghetti Code
  125. @maccath | Katy Ereira | #LaravelLive tests/Unit/BologneseTest.php private function eatenBolognese()

    { return new Bolognese($eaten = true); } private function uneatenBolognese() { return new Bolognese($eaten = false); } Testing: Spaghetti Code
  126. @maccath | Katy Ereira | #LaravelLive tests/Unit/BologneseTest.php private function expectGarlicBreadToBeEaten()

    { $garlicBread = Mockery::mock('overload:GarlicBread'); return $garlicBread->shouldReceive('eat'); // Return expectation. } Testing: Spaghetti Code
  127. @maccath | Katy Ereira | #LaravelLive tests/Unit/BologneseTest.php public function testEatDevouredBolognese()

    { $this->expectGarlicBreadToBeEaten()->never(); $this->eatenBolognese()->eat(); } public function testEatUneatenBolognese() { $this->expectGarlicBreadToBeEaten()->once(); $this->uneatenBolognese()->eat(); } Testing: Spaghetti Code
  128. @maccath | Katy Ereira | #LaravelLive Tricky Test Scenario Group

    #6 Private methods
  129. @maccath | Katy Ereira | #LaravelLive Private methods

  130. @maccath | Katy Ereira | #LaravelLive Private methods MCHammer.php class

    MCHammer { public function stop() { return $this->cantTouchThis(); } private function cantTouchThis() { return 'hammertime'; } }
  131. @maccath | Katy Ereira | #LaravelLive Private methods tests/Unit/MCHammerTest.php class

    MCHammerTest extends PHPUnit\Framework\TestCase { public function testCantTouchThis() { $mcHammer = new MCHammer(); $result = $mcHammer->cantTouchThis(); // Error; private method! $this->assertEquals('hammertime', $result); } }
  132. @maccath | Katy Ereira | #LaravelLive 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.
  133. @maccath | Katy Ereira | #LaravelLive Private methods tests/Unit/MCHammerTest.php class

    MCHammerTest extends PHPUnit\Framework\TestCase { public function testCantTouchThis() { $mcHammer = new MCHammer(); $result = $mcHammer->stop(); // Public method! $this->assertEquals('hammertime', $result); } }
  134. @maccath | Katy Ereira | #LaravelLive Private methods tests/Unit/MCHammerTest.php class

    MCHammerTest extends PHPUnit\Framework\TestCase { public function testCantTouchThis() { $mcHammer = new MCHammer(); $result = $mcHammer->stop(); $this->assertEquals('hammertime', $result); // Success! } }
  135. @maccath | Katy Ereira | #LaravelLive Thank you! Feedback welcome!

    https:/ /joind.in/talk/718c8