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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