MYTH CODE UNTESTABLE THE OF 

SEBASTIAN BERGMANN SEBASTIAN HEUER CREATOR OF PHPUNIT CO-FOUNDER OF THEPHP.CC DEVELOPER ADVOCATE DIE KARTENMACHEREI 

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TESTING CLEAN CODE IS EASY 

Headline LEGACY HELL 

TEMPLATE NEW 

template_new.php 

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IDML FO PNG PDF 

PDF PNG FO 

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1

(…) 2777 if ($isTranslationTool === false) { 2778 if (file_exists($configurationPath . 'spot' . $filenameSuffix . '.pdf')) { 2779 if ($isDebugMode) { 2780 echo $configurationPath . 'spot' . $filenameSuffix . '.pdf
'; 2781 echo 'GENERATING PAGES ' . $i . ' spot.pdf
'; 2782 } 2783 $pdf->setSourceFile($configurationPath . 'spot' . $filenameSuffix . '.pdf'); 2784 $tplIdx = $pdf->importPage($i + 1); 2785 $pdf->useTemplate($tplIdx, 0, 0); 2786 } elseif (file_exists($template_path . 'spot.pdf')) { 2787 if ($isDebugMode) { 2788 echo $template_path . 'spot.pdf
'; 2789 echo 'GENERATING PAGES ' . $i . ' spot.pdf
'; 2790 } 2791 $pdf->setSourceFile($template_path . 'spot.pdf'); 2792 $tplIdx = $pdf->importPage($i + 1); 2793 $pdf->useTemplate($tplIdx, 0, 0); 2794 } elseif ($isDebugMode) { 2795 echo 'NOT FOUND >> spot.pdf
'; 2796 } 2797 } (…) 

"The method execute() has an NPath complexity of 42261380675144684438377688955408190012304275410858 3958093751102384903715343564800000." "The configured NPath complexity threshold is 200." 

FOUR HUNDRED TWENTY-TWO SEXVIGINTILLION, SIX HUNDRED THIRTEEN QUINVIGINTILLION, EIGHT HUNDRED SIX QUATTUORVIGINTILLION, SEVEN HUNDRED FIFTY-ONE TREVIGINTILLION, FOUR HUNDRED FORTY-SIX DUOVIGINTILLION, EIGHT HUNDRED FORTY-FOUR UNVIGINTILLION, THREE HUNDRED EIGHTY-THREE VIGINTILLION, SEVEN HUNDRED SEVENTY-SIX NOVEMDECILLION, EIGHT HUNDRED EIGHTY-NINE OCTODECILLION, FIVE HUNDRED FIFTY-FOUR SEPTENDECILLION, EIGHTY-ONE SEXDECILLION, NINE HUNDRED QUINDECILLION, ONE HUNDRED TWENTY-THREE QUATTUORDECILLION, FORTY-TWO TREDECILLION, SEVEN HUNDRED FIFTY-FOUR DUODECILLION, ONE HUNDRED EIGHT UNDECILLION, FIVE HUNDRED EIGHTY-THREE DECILLION, NINE HUNDRED FIFTY-EIGHT NONILLION, NINETY-THREE OCTILLION, SEVEN HUNDRED FIFTY-ONE SEPTILLION, ONE HUNDRED TWO SEXTILLION, THREE HUNDRED EIGHTY-FOUR QUINTILLION, NINE HUNDRED THREE QUADRILLION, SEVEN HUNDRED FIFTEEN TRILLION, THREE HUNDRED FORTY-THREE BILLION, FIVE HUNDRED SIXTY-FOUR MILLION, EIGHT HUNDRED THOUSAND 

GLOBAL STATE A GAZILLION EXECUTION PATHS STATIC METHOD CALLS 

TESTING LEGACY CODE IS HARD impossible? 

"LET'S JUST REBUILD THIS FROM SCRATCH!" 

NO DOCUMENTATION ONLY CODE 

A Clockwork Orange - Ludovico technique; © Warner Bros 

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UNIT do we write the software right? 

TESTING LEGACY CODE IS HARD impossible? 

TESTING LEGACY CODE IS HARD Unit-testing unrefactored legacy code is impossible 

END-TO-END TESTING UNREFACTORED LEGACY CODE IS ALWAYS POSSIBLE 

ACCEPTANCE INTEGRATION UNIT END-TO-END do we write the right software? do we write the software right? execution time $$$ ¢ maintenance cost 

do we write the right software? END-TO-END $$$ 

IDML FO PNG PDF 

1 'KAM11GG', 10 'template_format' => 'F210', 11 'template_color' => 'C06', 12 // (...) 13 ]; 14 15 require __DIR__ .'/../src/template_new.php'; 16 17 $expectedFile = __DIR__ . '/fixtures/expected.fo'; 18 $actualFile = __DIR__ . '/../data/templates/KAM11GG/F210/C06/input.fo'; 19 20 $this->assertFileEquals($expectedFile, $actualFile); 21 } 22 } 

1 $design, 18 'template_format' => $format, 19 'template_color' => $color, 20 // (...) 21 ]; 22 23 require __DIR__ .'/../src/template_new.php'; 24 25 $actualFile = sprintf(__DIR__ . '/../data/templates/%s/%s/%s/input.fo', $design, $format, $color); 26 27 $this->assertFileEquals($expectedFile, $actualFile); 28 } 29 } 

BUT WHAT IF YOU DON'T KNOW INPUT AND/OR OUTPUT? 

CHARACTERIZATION TESTS "An attempt to lock existing behavior into an untested or undocumented system." http://wiki.c2.com/?CharacterizationTest 

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EXAMPLE 

1

$ php -d xdebug.auto_trace=1 -d xdebug.trace_format=1 \ -d xdebug.collect_params=5 -d xdebug.collect_return=1 legacy.php $ cat /tmp/trace.4251619279.xt Version: 2.5.3 File format: 4 TRACE START [2014-06-27 10:40:40] 1 0 0 0.000282 279896 {main} 1 /home/sb/legacy.php 0 0 2 1 0 0.000371 280136 add 1 /home/sb/legacy.php 7 2 aToxOw== aToyOw== 2 1 1 0.000440 280256 2 1 R aTozOw== 1 0 1 0.000470 280016 1 0 R aToxOw== 0.000648 8488 TRACE END [2014-06-27 10:40:40] $ de-legacy-fy generate-characterization-test add /tmp/trace.4251619279.xt CharacterizationTest CharacterizationTest.php de-legacy-fy 2.0.0 by Sebastian Bergmann. Generated class "CharacterizationTest" in file "CharacterizationTest.php" 

1 decode('aTozOw=='), $this->decode('aToxOw=='), $this->decode('aToyOw==')) 19 ); 20 } 21 22 /** 23 * @param string $value 24 * @return mixed 25 */ 26 private function decode($value) 27 { 28 return unserialize(base64_decode($value)); 29 }
 30 31 32 33 34 35 36 37 38 } 31 /** 32 * @dataProvider provider 33 */ 34 public function testAddFunctionWorksLikeItUsedTo($expected, $a, $b) 35 { 36 $this->assertEquals($expected, add($a, $b)); 37 } 

BACK TO OUR CASE 

NEXT: REFACTOR TO ALLOW INTEGRATION TESTING 

MOVE CODE INTO CLASS 

1 getBasePath(), 0, -1); // remove ending slash 24 $configurationRoot = $oConfig->getConfigByPath('path/configurations'); 25 $templateRoot = ''; // setted up in line 382 (template switch) 26 $sFopConfigRelative = $oConfig->getConfigByPath('path/fop/config'); 27 $sFopConfigAbsolute = $basePath . '/' . $sFopConfigRelative; 28 $usedDieCut = (isset($_REQUEST['diecut']) && !empty($_REQUEST['diecut']) && 'D53' == $_REQUEST['diecut'] ? 29 $_REQUEST['diecut'] : ''); 30 $configurationID = (isset($_REQUEST['configurationID'])) ? $_REQUEST['configurationID'] : null; 

INTRODUCE DEPENDENCY INJECTION 

1 config = $config; 17 $this->idmlParser = $idmlParser; 18 $this->request = $request; 19 } 20 21 public function execute() { 22 $configurationIdChecker = new ConfigurationIdChecker(); 23 24 $templateFormatParameter = $this->request->getFormat(); 25 $templateDesignParameter = $this->request->getDesign(); 26 $templateColorParameter = $this->request->getColor(); 27 28 $basePath = substr($this->config->getBasePath(), 0, -1); // remove ending slash 29 $configurationRoot = $this->config->getConfigByPath('path/configurations'); 30 $templateRoot = ''; // setted up in line 382 (template switch) 31 $sFopConfigRelative = $this->config->getConfigByPath('path/fop/config'); 

ACCEPTANCE INTEGRATION END-TO-END do we write the right software? do we write the software right? execution time $$$ ¢ maintenance cost 

USE TESTS TO WRITE NEW CODE 

CODE COVERAGE REPORT 

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Webserver Legacy Code FO 

Webserver Legacy Code New Code Abstraction Layer FO 

Webserver Legacy Code New Code Abstraction Layer $format === 'F040' FO 

BRANCH BY ABSTRACTION 

SUMMARY 

MEANINGFUL TESTS ARE A VALUABLE SOURCE OF DOCUMENTATION 

INTEGRATION TESTS ALLOW YOU TO WRITE NEW, CLEAN CODE 

USE BRANCH BY ABSTRACTION TO GRADUALLY MOVE FUNCTIONALITY TO NEW CODE 

WRITE UNIT TESTS FOR NEW CODE 

TESTING CLEAN CODE IS EASY 

THANK YOU! @inside_kam @belanur @thePHPcc @s_bergmann