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Introducing Tests In Legacy PHP Applications

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

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. $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
  4. 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
  5. 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.
  6. <?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): ?>
  7. 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"
  8. 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"
  9. 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, $range['end']); } }
  10. function fizzbuzz_normalize_range($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, ); }