Testing PHP Applications with PHPUnit 3

Testing PHP Applications with PHPUnit 3 Sebastian Bergmann November 2 nd 2006

Who I Am

Sebastian Bergmann.

Born 1978.

System Developer at eZ Systems AS.

Committer: PHP, PEAR, Gentoo Linux, ...

Creator of Open Source PHP projects such as PHPUnit.

Author on PHP and related topics.

Who Are You?

What is your PHP background?

OOP?

PHP 5?

PHPUnit?

The Need for Testing

PHP has evolved from a niche language for small websites to a powerful tool making strong inroads into large-scale, business-critical Web-based systems.

For instance, financial institutions use PHP to develop and maintain solutions for Basel II Credit Rating.

Critical business logic like this needs to work correctly.

But how do you ensure that it does?

You test it, of course.

Gateway Drug to Test Infection <?php class Calculator { public function add ( $a , $b ) { return $a + $b ; } } ?>

Gateway Drug to Test Infection <?php class Calculator { /** * @test (0,0) == 0 * @test (0,1) == 1 * @test (1,0) == 1 * @test (1,1) == 2 * @test (1,2) != 3 */ public function add ( $a , $b ) { return $a + $b ; } } ?>

Gateway Drug to Test Infection

Start from the Beginning

We just used the Skeleton Generator of PHPUnit 3 to automatically generate (and run) tests from source code annotations.

While this is handy for simple test cases like the ones in the previous example, it does not cater well to more complex test scenarios.

So let us take a step back and start from the beginning ...

Testing Software

Unit Testing

Runnable code-fragments (Unit Tests) test the correctness of parts (units) of the software.

System Testing

Conducted on a complete, integrated system to evaluate the system's compliance with its specified requirements. (from Wikipedia)

Non-Functional Testing

Performance.

Stability.

Usability.

Tool Support for Testing

To make (code) testing viable, good tool support is needed.

This is where a testing framework such as PHPUnit comes into play.

Requirements

Reusable test environment.

Strict separation of production code and test code.

Automatic execution of test code.

Analysis of the result.

Easy to learn to use and easy to use.

Testing PHP Applications

Unit Testing

PHPUnit

SimpleTest

System Testing

Selenium

PHPUnit + Selenium

Non-Functional Tests

Performance, Load, Stress, Reliability, Availability

ab, httperf, JMeter, Grinder, OpenSTA, ...

Security

Chorizo

PHPUnit http://www.phpunit.de/

Installing PHPUnit

PHPUnit TextUI TestRunner

Writing a Test Case <?php require_once 'PHPUnit/Framework.php' ; require_once 'Calculator.php' ; class CalculatorTest extends PHPUnit_Framework_TestCase { public function testAdd () { $calculator = new Calculator ; $this -> assertEquals ( 0 , $calculator -> add ( 0 , 0 )); $this -> assertEquals ( 1 , $calculator -> add ( 0 , 1 )); $this -> assertEquals ( 1 , $calculator -> add ( 1 , 0 )); $this -> assertEquals ( 2 , $calculator -> add ( 1 , 1 )); $this -> assertNotEquals ( 3 , $calculator -> add ( 1 , 2 )); } } ?>

Running a Test Case

Writing a Test Case <?php require_once 'PHPUnit/Framework.php' ; require_once 'Calculator.php' ; class CalculatorTest extends PHPUnit_Framework_TestCase { protected $calculator ; protected function setUp () { $this -> calculator = new Calculator ; } public function testAdd () { $this -> assertEquals ( 0 , $this -> calculator -> add ( 0 , 0 )); } // ... ?>

Running a Test Case

Testing Practices

You can always write more tests.

However, you will quickly find that only a fraction of the tests you can imagine are actually useful.

What you want is to write tests that fail even though you think they should work, or tests that succeed even though you think they should fail.

Another way to think of it is in cost / benefit terms.

You want to write tests that will pay you back with information. (Erich Gamma)

Testing Practices

During Development

When you need to make a change to the internal structure of the software you are working on to make it easier to understand and cheaper to modify without changing its observable behavior, a test suite is invaluable in applying these so called refactorings safely.

Otherwise, you might not notice the system breaking while you are carrying out the restructuring.

Testing Practices

During Debugging

Verify that you can reproduce the defect.

Find the smallest-scale demonstration of the defect in the code.

Write an automated test that fails now but will succeed when the defect is fixed.

Fix the defect.

Finding the smallest reliable reproduction of the defect gives you the opportunity to really examine the cause of the defect.

The new test ensures that you really fix it.

The old tests ensure that you do not introduce a new defect.

The PHPUnit API

Organizing Tests into Suites

Application/

Package/

Class (Application/Package/Class.php)

...

...

Tests/

AllTests.php

Package/

AllTests.php

ClassTest (Application/Tests/Package/ClassTest.php)

Organizing Tests into Suites <?php require_once 'PHPUnit/Framework/TestSuite.php' ; require_once 'Application/Tests/Package/AllTests.php' ; class AllTests { public static function suite () { $suite = new PHPUnit_Framework_TestSuite ( 'Project' ); $suite -> addTest ( Package_AllTests :: suite ()); return $suite ; } } ?>

Organizing Tests into Suites <?php require_once 'PHPUnit/Framework/TestSuite.php' ; require_once 'Application/Tests/Package/ClassTest.php' ; class Package_AllTests { public static function suite () { $suite = new PHPUnit_Framework_TestSuite ( 'Package' ); $suite -> addTestSuite ( 'Package_ClassTest' ); return $suite ; } } ?>

Who Uses PHPUnit

eZ Systems AS

eZ Components

~ 2.500 tests

Custom test runner based on PHPUnit_TextUI_TestRunner

Zend Technolgies Ltd.

Zend Framework

~ 400 tests (main library), ~ 1.000 tests (incubator)

PHP-GTK

IBM SDO

Agavi

Creole

Propel

Phing

Serendipity

...

PHPUnit at eZ Systems AS

New eZ Component

Write a design document.

Discussion, Review, ...

Write the tests.

Write the code.

Existing eZ Component

No code change without a ticket in the issue tracker.

No code change without running the existing tests.

No bug fix without new test(s) for the bug.

No feature addition without tests for the new feature.

You Have Seen Nothing Yet

We only scratched the surface.

{Writing | Organizing | Running} tests.

PHPUnit can do much more:

Mock Objects (port of jMock).

Code Coverage (needs Xdebug).

Incomplete tests (port of junitour) and Skipped Tests.

Agile Documentation (port of TestDox).

Logging of test execution in XML, TAP, or AT&T GraphViz markup and to PEAR::Log targets.

Integrates with CruiseControl, Selenium, PHPEclipse, and Phing.

Code Coverage

Selenium Integration

CruiseControl Integration

PHPEclipse Integration

Shameless Plug ;-)

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Testing PHP Applications with PHPUnit 3

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