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 yeild better results.

As presented at SunShinePHP, February 2013

Transcript

1. @jcarouth / #ssphp also known as testing from the pit of despair Introducing Tests in Legacy PHP Applications
2. Howdy! I am Jeff Carouth I have written many, many lines of legacy code. @jcarouth I work at Liftopia employing the techniques I am going to present today.
3. What He Said
4. Legacy Code?
5. Legacy Code IS difficult to change often unstructured and likely incomprehensible “Test resistant”
6. $body->compile_dir = $body->template_dir."/compiled"; //determine the controller that should be used for this request based on which // controller name is passed through the query string. If there is not a // controller name in the query string, we will assume that the request is for // the index page if ( true == isset( $_GET['controller'] ) && true == is_string( $_GET['controller']) && $_GET['c $page = trim( $_GET['controller'] ); unset( $_GET['controller'] ); } else { $page = ""; } // If we have a separate intro page defined, it should be rendered. if( SEPARATE_INTRO !== false && $page === "" ) { if( true == is_file( "controllers/" . SEPARATE_INTRO . ".php" ) ) { include_once "controllers/" . SEPARATE_INTRO . ".php"; } $body->display( SEPARATE_INTRO . ".html" ); } else { $content = new Smarty(); $content->template_dir = "html"; $content->compile_dir = $body->template_dir."/compiled"; if( $page === "" ) { $page = DEFAULT_PAGE; } // Determine what, if any, view should be presented to the client. If there is
7. Should Vs. Must
8. RESIST the urge to Rewrite
9. REFACTOR only what is necessary for tests
10. Legacy Code Change Algorithm 1. Identify change points. 2. Find test points. 3. Break dependencies. 4. Write tests. 5. Make changes and refactor. Source: Working Effectively with Legacy Code by Michael Feathers
11. Break Dependencies Without Tests In Place? Migraine.
12. Mechanism For Feedback
13. Acceptance Tests masquerade as pinning tests
15. Test Introduction Algorithm 1. Identify what you need to change. 2. Write pinning test for impacted behavior. 3. Locate test point for unit test. 4. Break dependencies. 5. Write tests. 6. Make changes and refactor. 7. Repeat 5 and 6 until change is completed.
16. The FizzBuzzer Because, really, people will fund anything
18. Anonymous users can run FizzBuzz but only up to to the number 100
19. Whether the job is big or small, do it right or not at all
20. Identify Change Points
21. <?php require_once dirname(__FILE__) . "/global.php"; if (sizeof($_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): ?>
22. Write Pinning Tests
23. 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"
25. Refactor and Make Changes
26. 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"
28. 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, $range['end']); } }
29. function fizzbuzz_normalize_range($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, ); }
33. Freedom to Refactor FEARLESSLY
34. Create Abstractions expose the API you want, guided by tests
35. Thank You! Questions? http://speakerdeck.com/jcarouth @jcarouth | jcarouth@gmail.com https://joind.in/8025