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.

Transcript

1. @jcarouth / #lsp13
   also known as testing from the pit of despair
   Introducing Tests in
   Legacy PHP Applications
   Friday, June 28, 13
   

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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.
   Friday, June 28, 13
   

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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
   // not a view request assign an empty string (default view).
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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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14. Friday, June 28, 13
    

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15. Friday, June 28, 13
    

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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"
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17. //features/bootstrap/FeatureContext.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!"'),
    );
    }
    }
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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.
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19. The FizzBuzzer
    Because, really, people will fund anything
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20. Friday, June 28, 13
    

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21. Anonymous users can run
    FizzBuzz but only up to to the
    number 100
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22. Whether the job is big
    or small, do it right or
    not at all
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23. Identify Change Points
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24. 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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25. Write Pinning Tests
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26. 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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27. Friday, June 28, 13
    

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28. Refactor and Make Changes
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29. 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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30. Friday, June 28, 13
    

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31. 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, $range['end']);
    }
    }
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32. function fizzbuzz_normalize_range($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. Friday, June 28, 13
    

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34. Friday, June 28, 13
    

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35. Friday, June 28, 13
    

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36. summary
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37. Freedom to Refactor
    FEARLESSLY
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38. Create Abstractions
    expose the API you want, guided by tests
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39. 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);
    }
    }
    ?>
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40. 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'),
    $this->rangeProcessor->process(1, 5)
    );
    }
    }
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41. class RangeProcessor
    {
    public function process($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 $number;
    }
    }
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42. function fizzbuzz_for_range($start, $end) {
    $f = array();
    for ($i = $start; $i <= $end; $i++) {
    $f[] = fizzbuzz_of($i);
    }
    return $f;
    }
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43. function fizzbuzz_for_range($start, $end) {
    $processor = new RangeProcessor();
    return $processor->process($start, $end);
    }
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44. 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.
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45. Thank You! Questions?
    http://speakerdeck.com/jcarouth
    @jcarouth | jcarouth@gmail.com
    https://joind.in/8683
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