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
   

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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.
   

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3. What
   He
   Said
   

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4. Legacy Code?
   

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5. Legacy Code IS
   difficult to change
   often unstructured
   and likely incomprehensible
   “Test resistant”
   

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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
   

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7. Should Vs. Must
   

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8. RESIST
   the urge to
   Rewrite
   

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9. REFACTOR
   only what is necessary
   for tests
   

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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
    

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11. Break Dependencies
    Without Tests In Place? Migraine.
    

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12. Mechanism For
    Feedback
    

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13. Acceptance Tests
    masquerade as pinning tests
    

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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.
    

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16. The FizzBuzzer
    Because, really, people will fund anything
    

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18. Anonymous users can run
    FizzBuzz but only up to to the
    number 100
    

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19. Whether the job is big
    or small, do it right or
    not at all
    

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20. Identify Change Points
    

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21. 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);
    }
    ?>
    
    
    
    
    FizzBuzz!
    
    Result
    
    

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22. Write Pinning Tests
    

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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"
    

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25. Refactor and Make Changes
    

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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"
    

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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']);
    }
    }
    

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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,
    );
    }
    

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33. Freedom to Refactor
    FEARLESSLY
    

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34. Create Abstractions
    expose the API you want, guided by tests
    

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35. Thank You! Questions?
    http://speakerdeck.com/jcarouth
    @jcarouth | jcarouth@gmail.com
    https://joind.in/8025
    

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