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Introducing Tests In Legacy PHP Applications

0f930e13633535c1c4041e95b8881308?s=47 Jeff Carouth
February 08, 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 yeild better results.

As presented at SunShinePHP, February 2013

0f930e13633535c1c4041e95b8881308?s=128

Jeff Carouth

February 08, 2013
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  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

  14. None
  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

  17. None
  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"
  24. None
  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"
  27. None
  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, ); }
  30. None
  31. None
  32. None
  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