Introduction to PHPUnit & Best Practices

Introduction to PHPUnit & Best Practices Sebastian Bergmann July 20th 2009

Who I am  Sebastian Bergmann  Involved in the PHP project since 2000  Creator of PHPUnit  Co-Founder and Principal Consultant with thePHP.cc

The Bank Account Example BankAccount.php <?php class BankAccount { protected $balance = 0; public function getBalance() { return $this->balance; } protected function setBalance($balance) { if ($balance >= 0) { $this->balance = $balance; } else { throw new RuntimeException; } } public function depositMoney($balance) { $this->setBalance($this->getBalance() + $balance); } public function withdrawMoney($balance) { $this->setBalance($this->getBalance() - $balance); } } ?>

The Bank Account Example BankAccountTest.php <?php require_once 'BankAccount.php'; class BankAccountTest extends PHPUnit_Framework_TestCase { }

The Bank Account Example BankAccountTest.php <?php require_once 'BankAccount.php'; class BankAccountTest extends PHPUnit_Framework_TestCase { public function testBalanceIsInitiallyZero() { } }

The Bank Account Example BankAccountTest.php <?php require_once 'BankAccount.php'; class BankAccountTest extends PHPUnit_Framework_TestCase { public function testBalanceIsInitiallyZero() { $ba = new BankAccount; $this->assertEquals(0, $ba->getBalance()); return $ba; } }

The Bank Account Example BankAccountTest.php <?php require_once 'BankAccount.php'; class BankAccountTest extends PHPUnit_Framework_TestCase { public function testBalanceIsInitiallyZero() { $ba = new BankAccount; $this->assertEquals(0, $ba->getBalance()); return $ba; } /** * @depends testBalanceIsInitiallyZero * @expectedException RuntimeException */ public function testBalanceCannotBecomeNegative(BankAccount $ba) { $ba->withdrawMoney(1); } }

The Bank Account Example BankAccountTest.php <?php require_once 'BankAccount.php'; class BankAccountTest extends PHPUnit_Framework_TestCase { public function testBalanceIsInitiallyZero() { $ba = new BankAccount; $this->assertEquals(0, $ba->getBalance()); return $ba; } /** * @depends testBalanceIsInitiallyZero * @expectedException RuntimeException */ public function testBalanceCannotBecomeNegative(BankAccount $ba) { $ba->withdrawMoney(1); } /** * @depends testBalanceIsInitiallyZero * @expectedException RuntimeException */ public function testBalanceCannotBecomeNegative2(BankAccount $ba) { $ba->depositMoney(-1); } // ... }

The Bank Account Example BankAccountTest.php <?php require_once 'BankAccount.php'; class BankAccountTest extends PHPUnit_Framework_TestCase { // ... /** * @depends testBalanceIsInitiallyZero */ public function testDepositingMoneyWorks(BankAccount $ba) { $ba->depositMoney(1); $this->assertEquals(1, $ba->getBalance()); return $ba; } }

The Bank Account Example BankAccountTest.php <?php require_once 'BankAccount.php'; class BankAccountTest extends PHPUnit_Framework_TestCase { // ... /** * @depends testBalanceIsInitiallyZero */ public function testDepositingMoneyWorks(BankAccount $ba) { $ba->depositMoney(1); $this->assertEquals(1, $ba->getBalance()); return $ba; } /** * @depends testDepositingMoneyWorks */ public function testWithdrawingMoneyWorks(BankAccount $ba) { $ba->withdrawMoney(1); $this->assertEquals(0, $ba->getBalance()); } }

The Bank Account Example Running tests sb@ubuntu ~ % phpunit BankAccountTest PHPUnit 3.4.0 by Sebastian Bergmann. ..... Time: 0 seconds OK (5 tests, 5 assertions)

The Bank Account Example BankAccount.php <?php class BankAccount { protected $balance = 1; public function getBalance() { return $this->balance; } protected function setBalance($balance) { if ($balance >= 0) { $this->balance = $balance; } else { throw new RuntimeException; } } public function depositMoney($balance) { $this->setBalance($this->getBalance() + $balance); } public function withdrawMoney($balance) { $this->setBalance($this->getBalance() - $balance); } } ?>

The Bank Account Example Running tests sb@ubuntu ~ % phpunit BankAccountTest PHPUnit 3.4.0 by Sebastian Bergmann. FSSSS Time: 0 seconds There was 1 failure: 1) BankAccountTest::testBalanceIsInitiallyZero Failed asserting that <integer:1> matches expected <integer:0>. /home/sb/BankAccountTest.php:7 FAILURES! Tests: 1, Assertions: 1, Failures: 1, Skipped: 4.

The Bank Account Example Running tests sb@ubuntu ~ % phpunit --verbose BankAccountTest PHPUnit 3.4.0 by Sebastian Bergmann. FSSSS Time: 0 seconds There was 1 failure: 1) BankAccountTest::testBalanceIsInitiallyZero Failed asserting that <integer:1> matches expected <integer:0>. /home/sb/BankAccountTest.php:7 There were 4 skipped tests: 1) BankAccountTest::testBalanceCannotBecomeNegative This test depends on "BankAccountTest::testBalanceIsInitiallyZero" to pass. 2) BankAccountTest::testBalanceCannotBecomeNegative2 This test depends on "BankAccountTest::testBalanceIsInitiallyZero" to pass. 3) BankAccountTest::testDepositingMoneyWorks This test depends on "BankAccountTest::testBalanceIsInitiallyZero" to pass. 4) BankAccountTest::testWithdrawingMoneyWorks This test depends on "BankAccountTest::testDepositingMoneyWorks" to pass. FAILURES! Tests: 1, Assertions: 1, Failures: 1, Skipped: 4.

The Bank Account Example TestDox: Report test result as executable specification sb@ubuntu ~ % phpunit --testdox BankAccountTest PHPUnit 3.4.0 by Sebastian Bergmann. BankAccount [x] Balance is initially zero [x] Balance cannot become negative [x] Depositing money works [x] Withdrawing money works

The Bank Account Example Code Coverage sb@ubuntu ~ % phpunit --coverage-html /tmp/report BankAccountTest PHPUnit 3.4.0 by Sebastian Bergmann. ..... Time: 0 seconds OK (5 tests, 5 assertions) Generating code coverage report, this may take a moment.

”The secret in testing is in writing testable code” Miško Hevery

Untestable Code Most people say Real issues  Make things private  Mix new with logic  Use final keyword  Look for things  Write long methods  Work in constructor  ...  Singletons  Global state  Static methods This slide contains material by Miško Hevery

Untestable Code Object Graph Construction Issues <?php Mixing object graph class Document { construction with work private $html; public function __construct($url) { $client = new HttpClient; $this->html = $client->get($url); } } Doing work in the constructor This slide contains material by Miško Hevery

Untestable Code Object Graph Construction Issues <?php class Document { private $html; public function __construct(HttpClient $client, $url) { $this->html = $client->get($url); } } Doing work in the constructor This slide contains material by Miško Hevery

Untestable Code Decouple object graph construction from other work <?php class DocumentFactory { public function __construct(HttpClient $client) { $this->client = $client; } public function build($url) { return new Document($this->client->get($url)); } } This slide contains material by Miško Hevery

Untestable Code Decouple object graph construction from other work <?php class DocumentFactory { public function __construct(HttpClient $client) { $this->client = $client; } public function build($url) { return new Document($this->client->get($url)); } } class Document { private $html; public function __construct($html) { $this->html = $html; } } This slide contains material by Miško Hevery

Untestable Code Global State  Global variables  Static variables in classes  Static variables in functions and methods  Persistent Data  Database  Filesystem  Distributed Data  memcached

Untestable Code Global Variables in PHP  A variable $foo declared in the global scope is stored in $GLOBALS['foo'].  $GLOBALS is a so-called superglobal.  Superglobals are built-in variables that are available in all scopes.  $GLOBALS['foo'] can be used to access the global variable $foo in the scope of a function or method  global $foo; can be used to create a local variable with a reference to the global variable.

Untestable Code Global Variables in PHP $GLOBALS = array( 'GLOBALS' => &$GLOBALS, '_ENV' => array(), '_POST' => array(), '_GET' => array(), '_COOKIE' => array(), '_SERVER' => array(), '_FILES' => array(), '_REQUEST' => array() );

Untestable Code PHPUnit and Global Variables  Default Behaviour  Backup $GLOBALS before the execution of a test  Run the test  Restore $GLOBALS after the execution of a test  $backupGlobals = FALSE  Do not backup and restore $GLOBALS  $backupGlobalsBlacklist = array()  Backup and restore $GLOBALS but not the variables listed in the array

Untestable Code PHPUnit and Static Attributes  Default Behaviour  Backup static attributes of user-defined classes before the execution of a test  Run the test  Restore static attributes of user-defined classes after the execution of a test  $backupStaticAttributes = FALSE  Do not backup and restore static attributes of user- defined classes  $backupStaticAttributesBlacklist = array()  Backup and restore static attributes of user-defined classes but not the variables listed in the array

Untestable Code Hidden Global State  Loaded source files  Loaded classes and functions  Sent HTTP headers  new DateTime()  time()  mktime()  rand() This slide contains material by Miško Hevery

Testable Code Selected Aspects of Testability  Few Branches  More branches increase complexity  Higher complexity leads to more errors  Higher complexity makes testing harder  Few Dependencies  Improved isolation for defect localization  Should be injectable to be replacable by test-specific equivalents

PHPUnit Best Practices Use an XML Configuration File <?xml version="1.0" encoding="UTF-8"?> <phpunit backupGlobals="false" backupStaticAttributes="false" syntaxCheck="false"> </phpunit>

PHPUnit Best Practices Use an XML Configuration File <?xml version="1.0" encoding="UTF-8"?> <phpunit backupGlobals="false" backupStaticAttributes="false" syntaxCheck="false"> <testsuites> <testsuite name="My Test Suite"> <directory>path/to/dir</directory> </testsuite> </testsuites> </phpunit>

PHPUnit Best Practices Use an XML Configuration File <?xml version="1.0" encoding="UTF-8"?> <phpunit backupGlobals="false" backupStaticAttributes="false" syntaxCheck="false"> <php> <const name="foo" value="bar"/> <var name="foo" value="bar"/> <ini name="foo" value="bar"/> </php> </phpunit>

PHPUnit Best Practices Use Code Coverage Whitelisting <?xml version="1.0" encoding="UTF-8"?> <phpunit backupGlobals="false" backupStaticAttributes="false" syntaxCheck="false"> <filter> <whitelist addUncoveredFilesFromWhitelist="true"> <directory suffix=".php">path/to/dir</directory> </whitelist> </filter> </phpunit>

PHPUnit Best Practices Make the Code Coverage information more meaningful /** * @covers Object_Freezer::freeze */ public function testFreezingAnObjectWorks() { $this->assertEquals( array( /* ... */ ), $this->freezer->freeze(new A(1, 2, 3)) ); }

PHPUnit Best Practices Exploit dependencies between tests /** * @covers Object_Freezer::freeze * @covers Object_Freezer::thaw * @depends testFreezingAnObjectWorks */ public function testFreezingAndThawingAnObjectWorks() { $object = new A(1, 2, 3); $this->assertEquals( $object, $this->freezer->thaw( $this->freezer->freeze($object) ) ); }

PHPUnit Best Practices Decouple test code from complex / large sets of test data <?php class DataTest extends PHPUnit_Framework_TestCase { /** * @dataProvider providerMethod */ public function testAdd($a, $b, $c) { $this->assertEquals($c, $a + $b); } public function providerMethod() { return array( array(0, 0, 0), array(0, 1, 1), array(1, 1, 3), array(1, 0, 1) ); } }

PHPUnit Best Practices Decouple test code from complex / large sets of test data sb@ubuntu ~ % phpunit DataTest PHPUnit 3.4.0 by Sebastian Bergmann. ..F. Time: 0 seconds There was 1 failure: 1) testAdd(DataTest) with data (1, 1, 3) Failed asserting that <integer:2> matches expected value <integer:3>. /home/sb/DataTest.php:19 FAILURES! Tests: 4, Assertions: 4, Failures: 1.

PHPUnit Best Practices Write code that allows you to disable PHPUnit features  Syntax Check  Backup/Restore of global variables  Backup/Restore of static attributes

The End Thank you for your interest! These slides will be posted on http://slideshare.net/sebastian_bergmann

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Introduction to PHPUnit & Best Practices

by Sebastian Bergmann on Jul 21, 2009

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Introduction to PHPUnit & Best Practices — Presentation Transcript