ZendCon 2013 - Introducing Tests in Legacy PHP Applications

You know testing is beneficial to your project. You are familiar with merits and caveats of test-driven development. But the project you’re hacking on right now is what most would call a legacy application. How do you apply your test knowledge to an application that doesn’t lend itself to traditional unit testing? The answer most will give is, “you don’t,” but we’re going to look at ways to write tests now that will allow you to improve and refactor your application to evolve the code to a more manageable state. The traditional “easy” route to dealing with legacy code is to rewrite but a little patience and skill applied to writing tests will yield better results.

Transcript

1. @jcarouth / #zendcon also known as testing from the pit of despair Introducing Tests in Legacy PHP Applications
2. JEFF CAROUTH DEVELOPER AT LIFTOPIA @jcarouth jcarouth@gmail.com Freenode: #phpmentoring
3. What He Said
4. Legacy 1.
5. Legacy Code IS difficult to change often unstructured and likely incomprehensible “Test resistant”
6. Should Vs. Must dilemma
7. RESIST the urge to Rewrite
8. REFACTOR only what is necessary for tests
9. Algorithms 2.
10. Legacy Code Change Algorithm 1. Identify change points. 2. Find test points. 3. Break dependencies. 4. Write tests. 5. Make changes and refactor. Source: Working Effectively with Legacy Code by Michael Feathers
11. Break Dependencies Without Tests In Place? Migraine.
12. Mechanism For Feedback
13. Acceptance Tests masquerade as pinning tests
16. //features/registereduser.feature Feature: Registered users can run fizzbuzz As a registered fizzbuzzer I want to be able to run fizzbuzz Background: Given An account exists for user "behat" password "letmein" When I am on homepage And I log in as "behat" with password "letmein" Scenario: Run fizzbuzz past anonymous limit When I run fizzbuzz on range "95" to "102" Then I should see "Buzz Fizz 97 98 Fizz Buzz 101 Fizz" Scenario: Cannot exceed maximum range When I run fizzbuzz on range "1" to "302" Then I should see "The range you requested is beyond the maximum… And I should see "298 299 FizzBuzz 301" But I should not see "299 FizzBuzz 301 302"
17. //features/bootstrap/FeatureContext.php <?php // A bunch of use statements and requires go here /** * Features context. */ class FeatureContext extends MinkContext { /** * Runs the fizzbuzz algorithm for given range. * * @When /^I run fizzbuzz on range "([^"]*)" to "([^"]*)"$/ */ public function iRunFizzBuzzOnRange($start, $end) { return array( new Step\When('I fill in "start" with "'.$start.'"'), new Step\When('I fill in "end" with "'.$end.'"'), new Step\When('I press "FizzBuzz!"'), ); } }
18. Test Introduction Algorithm 1. Identify what you need to change. 2. Write pinning test for impacted behavior. 3. Locate test point for unit test. 4. Break dependencies. 5. Write tests. 6. Make changes and refactor.
19. Example 3.
20. The FizzBuzzer Because, really, people will fund anything
22. Anonymous users can run FizzBuzz but only up to to the number 100
23. Whether the job is big or small, do it right or not at all
24. Identify Change Points
25. <?php require_once dirname(__FILE__) . "/global.php"; if (sizeof($_POST) <= 0) { header("Location: index.php"); } $start = filter_var($_POST['start'], FILTER_VALIDATE_INT); $end = filter_var($_POST['end'], FILTER_VALIDATE_INT); if (false === $start || false === $end) { die('Hackers go away!'); } require_once "include/fizzbuzz.funcs.php"; $results = fizzbuzz_for_range($start, $end); //log this run if the user is logged in if (user_logged_in()) { user_log_run(user_get_id(), $start, $end); } ?> <?php include dirname(__FILE__) . "/templates/header.phtml"; ?> <form class="form-inline" action="process.php" method="POST"> <input type="text" name="start" placeholder="Start" /> <input type="text" name="end" placeholder="End" /> <button type="submit" class="btn btn-primary">FizzBuzz!</button> </form> <h2>Result</h2> <?php if (false !== $results): ?>
26. Write Pinning Tests
27. Feature: Anonymous Run FizzBuzz As a non-registered fizzbuzz enthusiast I need to be able to run fizzbuzz on a range of numbers So that I can get my fix of fizzbuzziness Scenario: Anonymous users should be able to run the fizzbuzzer When I am on homepage And I run fizzbuzz on range "12" to "20" Then I should see "Fizz 13 14 FizzBuzz 16 17 Fizz 19 Buzz" Scenario: Anonymous users should be able to run a second fizzbuzz When I am on homepage And I run fizzbuzz on range "3" to "5" Then I should see "Fizz 4 Buzz" When I run fizzbuzz on range "9" to "12" Then I should see "Fizz Buzz 11 Fizz"
29. Refactor and Make Changes
30. Then I should see "Fizz 13 14 FizzBuzz 16 17 Fizz 19 Buzz" Scenario: Anonymous users should be able to run a second fizzbuzz When I am on homepage And I run fizzbuzz on range "3" to "5" Then I should see "Fizz 4 Buzz" When I run fizzbuzz on range "9" to "12" Then I should see "Fizz Buzz 11 Fizz" Scenario: Anonymous users should not be able to exceed 100 When I am on homepage And I run fizzbuzz on range "95" to "101" Then I should see "101 is beyond the maximum value, 100" And I should see "Buzz Fizz 97 98 Fizz Buzz"
32. class FizzBuzzTest extends \PHPUnit_Framework_TestCase { /** * @test */ public function normalizeRangeForAnonShouldTruncateAt100() { $normalizedRange = fizzbuzz_normalize_range(95, 101, false); $this->assertTrue($normalizedRange['can_process']); $this->assertEquals(100, $normalizedRange['end']); } /** * @test */ public function signedInUsersCanUseIntegersOver100() { $range = fizzbuzz_normalize_range(95, 101, true); $this->assertTrue($range['can_process']); $this->assertEquals(101, $range['end']); } }
33. function fizzbuzz_normalize_range($start, $end, $is_user = false) { $can_process = true; $message = ''; if (!$is_user) { //anon can only fizzbuzz for ranges up to 100 if ($end > 100) { $message = '$end.'is 'beyond the maximum value, 100” $end = 100; } } return array( 'can_process' => $can_process, 'message' => $message, 'start' => $start, 'end' => $end, ); }
37. +3 feature tests +2 Unit tests Added
38. Freedom to Refactor FEARLESSLY
39. Create Abstractions expose the API you want, guided by tests
40. <?php require_once dirname(__FILE__) . "/global.php"; //...snip... require_once dirname(__FILE__) . "/include/fizzbuzz.funcs.php"; $to_process = fizzbuzz_normalize_range( $start, $end, user_logged_in()); $results = false; if (false !== $to_process['can_process']) { $results = fizzbuzz_for_range( $to_process['start'], $to_process['end'] ); //log this run if the user is logged in if (user_logged_in()) { user_log_run(user_get_id(), $start, $end); } } ?>
41. <?php namespace Tests\FizzBuzzer; class RangeProcessorTest extends \PHPUnit_Framework_TestCase { /** @var \FizzBuzzer\RangeProcessor */ protected $rangeProcessor; public function setUp() { $this->rangeProcessor = new \FizzBuzzer\RangeProcessor(); } /** * @test */ public function shouldReturnValuesForSimpleRange() { $this->assertEquals( array(1, 2, 'Fizz', 4, 'Buzz'), $this->rangeProcessor->process(1, 5) ); } }
42. class RangeProcessor { public function process($start, $end) { $results = array(); foreach (range($start, $end) as $number) { $results[] = $this->fizzbuzzFor($number); } return $results; } private function fizzbuzzFor($number) { if ($number % 15 === 0) { return 'FizzBuzz'; } elseif ($number % 3 === 0) { return 'Fizz'; } elseif ($number % 5 === 0) { return 'Buzz'; } return $number; } }
43. function fizzbuzz_for_range($start, $end) { $f = array(); for ($i = $start; $i <= $end; $i++) { $f[] = fizzbuzz_of($i); } return $f; }
44. function fizzbuzz_for_range($start, $end) { $processor = new RangeProcessor(); return $processor->process($start, $end); }
45. Break Dependencies creating seams is your friend
46. namespace Fizzbuzzer; class Order { public $id; public function getPayments() { $paymentDao = new PaymentDao(); return $paymentDao->getOrderPayments($this->id); } }
47. namespace tests\Fizzbuzzer; use Fizzbuzzer\Order; class OrderTest extends \PHPUnit_Framework_TestCase { /** @test */ public function shouldReturnPaymentsAppliedToOrder() { $o = new Order(); $this->assertNotEmpty($o->getPayments()); } }
48. class Order { public $id; public function getPayments() { $paymentDao = $this->getPaymentDao(); return $paymentDao->getOrderPayments($this->id); } protected function getPaymentDao() { return new PaymentDao(); } }
49. class Order { public $id; public function getPayments() { $paymentDao = $this->getPaymentDao(); return $paymentDao->getOrderPayments($this->id); } public function setPaymentDao(PaymentDao $paymentDao) { $this->paymentDao = $paymentDao; } protected function getPaymentDao() { if (null === $this->paymentDao) { $this->paymentDao = new PaymentDao(); } return $this->paymentDao; } }
50. class OrderTest extends \PHPUnit_Framework_TestCase { /** @test */ public function shouldReturnPaymentsAppliedToOrder() { $paymentDao = $this->getMock('\\Fizzbuzzer\\PaymentDao'); $paymentDao->expects($this->any()) ->method('getOrderPayments') ->will($this->returnValue(array( $this->getMock('\\Fizzubzzer\\Payment') ))); $o = new Order(); $o->setPaymentDao($paymentDao); $this->assertNotEmpty($o->getPayments()); } }
51. Test Introduction Algorithm 1. Identify what you need to change. 2. Write pinning test for impacted behavior. 3. Locate test point for unit test. 4. Break dependencies. 5. Write tests. 6. Make changes and refactor.
52. Thanks. http://speakerdeck.com/jcarouth Q&A http://joind.in/9059 Jeff Carouth // @jcarouth // #zendcon13