Fighting Fear-Driven-Development With PHPUnit


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This talk was designed for PHP developers with limited or no experience in unit testing. I focus on describing the problem of fear-driven-development, and how test-driven-development can be used to improve the quality of your code.

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Fighting Fear-Driven-Development With PHPUnit

  1. 1. South Florida PHP Meetup Group
  2. 2.  James Fuller Web Developer Started unit testing in response to a new job developing on a large, buggy legacy application used by millions
  3. 3.  Afraid to make even tiny code changes due to unpredictable side-effects? Been burned by bugs that came back to life? Does sketchy code keep you up at night?
  4. 4. Imagine your code as a dark twisted forest thatyou must navigate.Nothing makes sense, there are no clear pathsand you are surrounded by bugs. Lots of bugs.How would you handle being stuck in thissituation?
  5. 5.  Some will be brave and foolish, cutting corners to move quickly through the forest. Some will be paralyzed by the thought of making the wrong move. Most will succumb to the bugs or die a horrible death trying to find a way out.
  6. 6. Modify code Brokesomething Run featureGod I hope Doesnt workthis works Modify Code
  7. 7.  Write tests Use PHPUnit to automate your tests Practice Test-Driven-Development Improve your design Enjoy the added value
  8. 8.  Can you prove it works? automatically? Can you change it and know it still works? without loading the browser? Can you promise that if it breaks, it will never break like that again? What about edge cases? You do care about edge cases, right?
  9. 9.  All developers practice some form of testing. Most PHP developers do it in the browser. What we want to do is automate testing with PHPUnit. Dont confuse apathy with laziness. Good coders automate repetitive tasks because they are lazy.
  10. 10.  Before you write new code When you fix a bug Before you begin refactoring code As you go, improving code coverageWe can use Test-Driven-Development to helpus maintain disclipline in writing our unit tests.
  11. 11.  The principle of unit testing is to verify that a unit of code will function correctly in isolation. A unit is the smallest testable part of an application, usually a function or method.
  12. 12. Understand RequirementsRefactor Write testsRun Tests Run Tests (PASS) (FAIL) Write Code
  13. 13.  Focus on design of system before implementation Changes are easier to make, with less side effects Documentation via example Less FEAR, more CONFIDENCE You have tests at the end!
  14. 14.  PHPUnit is an automated testing framework PHP development based upon xUnit (java). PHPUnit gives us an easy way to write tests, generate code coverage and improve the quality of our code.
  15. 15. Command line test runnerMature and expansive assertion libraryCode coverageMock objectsLots of extensionsFast & Configurable
  16. 16.  PEAR  best for system wide access to phpunit  hard to downgrade or change versions  dependencies can be tricky Github  allows the most control  easy to pack up in your version control system  lots of steps Phar (PHP Archive)  a single phar can be easily included in your projects  in development  many features dont work or dont work as expected
  17. 17.  Upgrade PEAR to the latest version  sudo pear upgrade PEAR Install PHPUnit  pear config-set auto_discover 1  pear install This will install the latest release of PHPUnit. Installing older versions is a bit trickier.
  18. 18.  pear install phpunit/DbUnit pear install phpunit/PHPUnit_Selenium pear install phpunit/PHPUnit_Story pear install phpunit/PHPUnit_TestListener_DBUS pear install phpunit/PHPUnit_TestListener_DBUS pear install phpunit/PHPUnit_TestListener_XHProf pear install phpunit/PHPUnit_TicketListener_Fogbugz pear install phpunit/PHPUnit_TicketListener_GitHub pear install phpunit/PHPUnit_TicketListener_GoogleCode pear install phpunit/PHPUnit_TicketListener_Trac pear install phpunit/PHP_Invoker
  19. 19.  Checkout source from github mkdir phpunit && cd phpunit git clone git:// git clone git:// … Still need PEAR to install YAML component pear install Make sure to add all these directories to your include_path Checking out specific versions of packages: cd phpunit git checkout 3.6
  20. 20.  Usage  phpunit [switches] UnitTest [UnitTest.php]  phpunit [switches] <directory> Common Switches  --stop-on-error Stop upon first error.  --stop-on-failure Stop upon first error or failure.  --debug Output debug info (test name)  -v|--verbose Output verbose information.  --bootstrap <file> Load this file before tests  --configuration <file> Specify config file (default phpunix.xml)
  21. 21.  PHPUnit runtime options can be defined using command line switches and/or xml (phpunit.xml) Bootstrap your application as needed before tests run (bootstrap.php) Define paths for code coverage output, logs, etc.
  22. 22. Its easy!! Include the autoloader in yourbootstrap or in your test cases:<?phprequire_once PHPUnit/Autoload.php;
  23. 23.  A test suite contains any number of test cases. A test case is a class that contains individual tests. A test is a method that contains the code to test something.
  24. 24. / lib/ Foo.php tests/ suite/ lib/ FooTest.php
  25. 25. <phpunit> <testsuites> <testsuite name="All Tests"> <directory>tests/suite</directory> </testsuite> <testsuite name="Some Tests"> <file>tests/suite/FooTest.php</file> <file>tests/suite/BarTest.php</file> </testsuite> </testsuites></phpunit>
  26. 26. A Fixture represents the known state of theworld. Object instantiation Database Records Preconditions & PostconditionsPHPUnit offers several built-in methods toreduce the clutter of setting up fixtures.
  27. 27. class FooTest extends PHPUnit_Framework_TestCase { //runs before each test method protected function setUp() {} //runs after each test method protected function tearDown() {} //runs before any tests public static function setUpBeforeClass() {} //runs after all tests public static function tearDownAfterClass() {}}
  28. 28. class FooTest extends PHPUnit_Framework_TestCase { protected $Foo; protected function setUp() { $this->Foo = new Foo; } public function testFoo () { $this->assertNull($this->Foo->method()); } public function testFoo1() { $this->assertNull($this->Foo->otherMethod()); }}
  29. 29. //method being tested in class Foopublic function reverseConcat($a, $b) { return strrev($a . $b);}//test method in class FooTestpublic function testReverseConcat() { $sut = new Foo; $actual = $sut->reverseConcat(Foo, Bar); $expected = raBooF; $this->assertEquals($expected, $actual);}
  30. 30.  An assertion is how we declare an expectation. Well-tested systems rely upon verification, not developer intuition. Things we can assert with PHPUnit  return values  certain methods/objects were called via Test Doubles  echo/print output
  31. 31. assertArrayHasKey() assertNull()assertClassHasAttribute() assertObjectHasAttribute()assertClassHasStaticAttribute() assertRegExp()assertContains() assertStringMatchesFormat()assertContainsOnly() assertStringMatchesFormatFile()assertCount() assertSame()assertEmpty() assertSelectCount()assertEqualXMLStructure() assertSelectEquals()assertEquals() assertSelectRegExp()assertFalse() assertStringEndsWith()assertFileEquals() assertStringEqualsFile()assertFileExists() assertStringStartsWith()assertGreaterThan() assertTag()assertGreaterThanOrEqual() assertThat()assertInstanceOf() assertTrue()assertInternalType() assertXmlFileEqualsXmlFile()assertLessThan() assertXmlStringEqualsXmlFile()assertLessThanOrEqual() assertXmlStringEqualsXmlString()
  32. 32. When assertions evaluate to TRUE the test will emit a PASS $this->assertTrue(true); $this->assertFalse(false); $this->assertEquals(foo, foo); $this->assertEmpty(array()); $this->assertNotIsSame(new stdClass, new stdClass); $this->assertArrayHasKey(foo, array(foo => bar)); $this->assertCount(2, array(apple, orange));
  33. 33. When assertions evaluate to FALSE the test will emit a FAILURE$this->assertTrue(false);$this->assertFalse(true);$this->assertEquals(foo, bar);$this->assertEmpty(array(foo));$this->assertIsSame(new stdClass, new stdClass);$this->assertArrayHasKey(foo, array());$this->assertCount(2, array(apple));
  34. 34.  game has 2 players players pick either rock, paper, or scissors rock beats scissors paper beats rock scissors beats paper round is a draw if both players pick the same object
  35. 35.  Isolation means that a unit of code is not affected by external factors. In practice we cant always avoid external dependencies, but we benefit from trying to reduce their impact on our tests. This means we need to be able to substitute external dependencies with test doubles.
  36. 36.  Test doubles are objects we use to substitute dependencies in our system under test. Stubs return prebaked values when its methods are called. Mocks are like programmable stubs. You can verify that methods are called correctly and perform more complex verification.
  37. 37.  PHPUnit provides a built in mocking framework. You can easily create test doubles that you can inject into your system under test. This allows you to swap out complex dependencies with controllable and verifiable objects.
  38. 38. public function testStub() { $stub = $this->getMock(Stub, array(foo)); $stub->expects($this->once()) ->method(foo) ->will($this->returnValue(bar)); $actual = $stub->foo(); $this->assertEquals(bar, $actual, "shouldhave returned bar");}
  39. 39.  Two ways to generate mock objects getMock() with arguments Mock Builder API
  40. 40. $this->getMock( $class_name, $mocked_methods, $constructor_args, $mock_class_name, $call_original_constructor, $call_original_clone_constructor, $disable_autoload);
  41. 41. $this->getMockBuilder($class_name) ->setMethods(array $methods) ->disableOriginalConstructor() ->disableOriginalClone() ->setConstructorArgs(array $args) ->setMockClassName($class_name) ->getMock();
  42. 42. $mock = $this->getMockBuilder(Foo) ->setMethods(array(someMethod)) ->getMock();$mock->expects($this->any()) ->method(someMethod) ->will( $this->onConsecutiveCalls(bar, baz) );$mock->someMethod(); //returns bar$mock->someMethod(); //returns baz
  43. 43. $mock = $this->getMockBuilder(Foo) ->setMethods(array(someMethod)) ->getMock();$mock->expects($this->any()) ->method(someMethod) ->will($this->throwException( new RuntimeException ));//throws a RuntimeException$mock->someMethod();
  44. 44. class WebService { protected $Http; public function __construct(Http $http) { $this->Http = $http; } public function getUrl($url = ) { return $this->Http->get($url); }}
  45. 45. require_once PHPUnit/Autoload.php;require_once WebService.php;class TestWebService extends PHPUnit_Framework_TestCase { public function testGetUrl_callsHttpCorrectly() { $http = $this->getMockBuilder(FakeClassName) ->setMethods(array(get)) ->setMockClassName(Http) ->getMock(); $http->expects($this->once()) ->method(get) ->with($url); //inject the mock via constructor $sut = new WebService($http); //test Http get $sut->getUrl(; }}
  46. 46.  Static method calls Instantiating objects directly (hard coupling) External resources (network, file system) Globals ($_GLOBALS, Singletons)
  47. 47. class Dependency {}class SystemUnderTest { public function badIdea() { $dependency = new Dependency; }}
  48. 48. class TwitterClient { function getTweets() { $url =; return Http::consume($url); }}
  49. 49. class TwitterClient { protected $Http; public function __construct(Http $http) { $this->Http = $http; } public function getTweets() { $url =; return $this->Http->consume($url); }}
  50. 50. class TestTwitterClient extendsPHPUnit_Framework_TestCase { public function testCantMockTwitter() { $mock = $this->getMockBuilder(Http) ->setMethods(array(consume)) ->getMock(); $sut = new TwitterClient($mock); $sut->getTweets(); }}
  51. 51. class Singleton { public $data; protected static $instance; private function __construct() {} private function __clone() {} public function getInstance() { if (!self::$instance) { self::$instance = new self; } return self::$instance; }}
  52. 52. class SystemUnderTest { public function setData($data) { Singleton::getInstance()->data = $data; } public function getData() { return Singleton::getInstance()->data; }}
  53. 53. class TestSystemUnderTest extendsPHPUnit_Framework_TestCase { public function testSingletonsAreFineAtFirst() { $sut = new SystemUnderTest; $sut->setData(foo); //passes $this->assertEquals(foo, $sut->getData()); } public function testSingletonsNeverDie() { $sut = new SystemUnderTest; $actual = $sut->getData(); //fails $this->assertNull($actual); }}
  54. 54.  Many frameworks come with built in testing facilities, or the ability to easily integrate with PHPUnit. Try to use the built-in testing tools. They usually do the heavy lifting of bootstrapping your application.
  55. 55.  Get your test harness working Get your feet wet first, testing smaller/trivial code Manual verification is prudent Improve your design, refactor Write tests for new code Write tests opportunistically