PHPUnit & Continuous Integration: An Introduction

PHPUnit &
Continuous Integration
An Introduction

Friday, 16 October 2009

PHPUnit & CI
• What is Unit Testing? • Best Practices

• Why Unit Test? • Automated Test Runs

• How to test • Continuous Integration

• Using PHPUnit • More features of CI

• Organising Tests

• Advanced PHPUnit


What is Unit Testing?
• In computer programming, Unit Testing is a
software veriﬁcation and validation method
in which a programmer tests if individual
units of source code are ﬁt for use.
(Wikipedia)
• A “unit” is the smallest testable part of an
application: a function or class method.


Why not Unit Test?

• Writing tests is boring!
• Writing tests makes development take
longer
• My code is perfect and has no bugs


Why Unit Test?

• You can’t prove that a program is bug free
• Reduces the cost of changes; proves
software still works as expected after
changes have been made.
• Takes pressure off


How To Test
• Tests should be repeatable, audited and
isolated.
• Repeatable: easy to run multiple times
• Audited: results should be collated and
displayed
• Isolated: one test should not affect other
tests and should only test one thing


Why PHPUnit?
• Makes it easy to run • Integrates with
tests in a repeatable, Continuous Integration
audited and isolated tools
fashion.
• Advanced features like:
• Complete port of JUnit Mock Objects, Database
3.8 testing, class skeleton
generation, Selenium
• Support integrated into
Eclipse, NetBeans & • Alternative: SimpleTest
other IDEs


Assertions
• assertArrayHasKey • assertGreaterThan

• assertClassHasAttribute • assertLessThan

• assertContains • assertNotNull

• assertFalse • assertRegExp

• assertFileEquals • assertSame

• assertFileExists • and many more!


A Basic Example

• Test case classes have a “Test” sufﬁx
• Test methods are preﬁxed “test”


Running Tests

• Tests can be run via:

• Command Line

• IDE

• Continuous
Integration


Fixtures
• Each test may require common operations
to set up the environment
• Environment should be returned to
previous state after the test
• Duplicating code is bad
• Solution: setUp( ) and tearDown( )


Fixture Example
• Database connection
and test object
instantiation are now
done in setUp( )

• Database connection is
closed in tearDown( )

• Connection reuse could
pollute tests!


Test Organisation
• PHPUnit allows
your to organise
your tests into
“Suites”

• Suites can include
other suites

• Allows you to test
everything in one
go


Advanced Usage

• Mock Objects & Stubs
• Database Testing
• Skeleton Generation
• Selenium
• Code Coverage


Mock Objects & Stubs
• Mock objects are used as stand ins for
genuine objects
• Stubs are replacements for real functions
that accept the same input but return a
known quantity
• Tests should not be dependant on code not
being tested, so we use mock objects and
stubs to replace them


Database Testing
• Put database into a known state before test
is run
• Using assertDataSetsEqual( ), the contents
of a database tested
• Data sets can be ﬁltered to remove
columns such as date, time
• Testing multiple DBs is hard, but possible

Skeleton Generation

• PHPUnit is able to generate a class
skeleton based on a test case
• PHPUnit is also able to do the reverse,
generate a test case skeleton based on a
class


Selenium

• Selenium performs end user testing of web
applications on any platform in any browser
• Allows you to test that a web application is
working as expected
• Technically this is not unit testing, but
acceptance testing


Code Coverage

• Requires Xdebug so PHPUnit can inspect
what code is running
• Tells you how much of your code is being
tested
• Helps to identify areas in need of testing or
new tests that need of testing


Best Practices
• Write testable code
• No globals
• Don’t create objects in constructors
• Don’t test private methods. Unit testing
tests the interface, not the implementation.
• Exploit dependencies between tests with
@depends


Automating Unit Tests

• Create a cron job to run tests
• Subversion pre-commit hook
• Subversion post-commit hook


• Can automate the running of unit tests
• More developers = more divergence
• The longer you go between integrating
work, the harder it is
• Continuous Integration constantly
integrates work
• Problems are exposed quickly

What Else Can CI Do?

• Generate Documentation
• Check Code Against Coding Standards
• Generate Metrics
• Code Coverage
• Project Mess Detection


for PHP

• Atlassian Bamboo
• CruiseControl
• phpUnderControl


phpUnderControl

• Available through PEAR on phpunit channel
• Uses Subversion, PHPUnit, Xdebug,
PHP_CodeSniffer, PHPDocumentor
• build.xml deﬁnes what phpUnderControl
will do in the build process


Summary

• Unit Testing: What it is and why we do it
• PHPUnit: How to Unit Test
• Continuous Integration: How it helps us
create high quality code


More Information

• http://www.phpunit.de
• http://phpundercontrol.org/
• Just ask!


PHPUnit & Continuous Integration: An Introduction

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