Introducing Tests In Legacy PHP Applications

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@jcarouth / #ssphp also known as testing from the pit of despair Introducing Tests in Legacy PHP Applications

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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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What He Said

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Legacy Code?

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

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$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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Should Vs. Must

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RESIST the urge to Rewrite

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REFACTOR only what is necessary for tests

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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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Break Dependencies Without Tests In Place? Migraine.

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Mechanism For Feedback

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Acceptance Tests masquerade as pinning tests

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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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The FizzBuzzer Because, really, people will fund anything

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

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

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Identify Change Points

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FizzBuzz!

Result

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Write Pinning Tests

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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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Refactor and Make Changes

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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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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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Freedom to Refactor FEARLESSLY

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Create Abstractions expose the API you want, guided by tests

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Thank You! Questions? http://speakerdeck.com/jcarouth @jcarouth | [email protected] https://joind.in/8025