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unit testing
Introduction to
WordPress
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Carl Alexander
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@twigpress
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carlalexander.ca
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No content
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This code worked the other day
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You need to protect
yourself
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Say hello to testing!
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testing is a HUGE field
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Focus on unit testing
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What is unit testing?
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Testing at the smallest
scale
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Input values into a
function
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Check what comes out
at the end
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Goal:
Constant behaviour
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Goal:
Safety net
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Goal:
Code quality
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in unit testing
Isolation
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Cornerstone
of unit testing
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Done using test doubles
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Magical machines
surrounding your code
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Gives you
ABSOLUTE control
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What is
my code doing?
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Not what is
WordPress doing?
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What makes
testable code
higher quality?
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Cyclomatic
complexity
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Maps unique
paths through
your code
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Code with
more paths is
harder to test
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Makes you write
smaller, less complex
functions
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WordPress tests
unit tests
VS
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WordPress tests are
integration tests
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Different relationship
with isolation
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It’s about how pieces of
code work together
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Isolating a piece of code
isn’t as necessary
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Neither is better
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Ideally, you do both
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Questions?
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The unit testing setup
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Operating System:
unix-based
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PHP version:
5.3 (for code) / 5.4 (for tests)
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Composer
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PHPUnit
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WP-CLI
(optional)
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Creating our
unit tested plugin
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wp
scaffold
plugin
unit-‐tested-‐plugin
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Add composer.json
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{
"name":
"carlalexander/unit-‐tested-‐plugin",
"type":
"project",
"description":
"A
unit
tested
WordPress
plugin",
"homepage":
"https://carlalexander.ca",
"license":
"GPL-‐3.0+",
"require":
{
"php":
">=5.3.0"
},
"require-‐dev":
{
"php-‐mock/php-‐mock-‐phpunit":
"^0.3"
}
}
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{
"name":
"carlalexander/unit-‐tested-‐plugin",
"type":
"project",
"description":
"A
unit
tested
WordPress
plugin",
"homepage":
"https://carlalexander.ca",
"license":
"GPL-‐3.0+",
"require":
{
"php":
">=5.3.0"
},
"require-‐dev":
{
"php-‐mock/php-‐mock-‐phpunit":
"^0.3"
}
}
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{
"name":
"carlalexander/unit-‐tested-‐plugin",
"type":
"project",
"description":
"A
unit
tested
WordPress
plugin",
"homepage":
"https://carlalexander.ca",
"license":
"GPL-‐3.0+",
"require":
{
"php":
">=5.3.0"
},
"require-‐dev":
{
"php-‐mock/php-‐mock-‐phpunit":
"^0.3"
}
}
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Modify bootstrap.php
(created by WP-CLI)
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$_tests_dir
=
getenv('WP_TESTS_DIR');
if
(
!$_tests_dir
)
$_tests_dir
=
'/tmp/wordpress-‐tests-‐lib';
require_once
$_tests_dir
.
'/includes/functions.php';
function
_manually_load_plugin()
{
require
dirname(
__FILE__
)
.
'/../unit-‐tested-‐plugin.php';
}
tests_add_filter(
'muplugins_loaded',
'_manually_load_plugin'
);
require
$_tests_dir
.
'/includes/bootstrap.php';
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Composer missing
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require_once(dirname(__DIR__)
.
'/vendor/autoload.php');
$_tests_dir
=
getenv('WP_TESTS_DIR');
if
(
!$_tests_dir
)
$_tests_dir
=
'/tmp/wordpress-‐tests-‐lib';
require_once
$_tests_dir
.
'/includes/functions.php';
function
_manually_load_plugin()
{
require
dirname(
__FILE__
)
.
'/../unit-‐tested-‐plugin.php';
}
tests_add_filter(
'muplugins_loaded',
'_manually_load_plugin'
);
require
$_tests_dir
.
'/includes/bootstrap.php';
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Our first plugin function
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namespace
UnitTestDemo;
/**
*
Get
a
plugin
option
from
the
WordPress
database.
*
*
@param
string
$name
*
*
@return
mixed
*/
function
demo_get_option($name)
{
return
get_option('demo_'
.
$name);
}
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namespace
UnitTestDemo;
/**
*
Get
a
plugin
option
from
the
WordPress
database.
*
*
@param
string
$name
*
*
@return
mixed
*/
function
demo_get_option($name)
{
return
get_option('demo_'
.
$name);
}
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namespace
UnitTestDemo;
/**
*
Get
a
plugin
option
from
the
WordPress
database.
*
*
@param
string
$name
*
*
@return
mixed
*/
function
demo_get_option($name)
{
return
get_option('demo_'
.
$name);
}
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Questions?
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Our first unit test
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namespace
UnitTestDemo;
use
phpmock\phpunit\PHPMock;
class
DemoTest
extends
\PHPUnit_Framework_TestCase
{
use
PHPMock;
//
...
}
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namespace
UnitTestDemo;
use
phpmock\phpunit\PHPMock;
class
DemoTest
extends
\PHPUnit_Framework_TestCase
{
use
PHPMock;
//
...
}
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namespace
UnitTestDemo;
use
phpmock\phpunit\PHPMock;
class
DemoTest
extends
\PHPUnit_Framework_TestCase
{
use
PHPMock;
//
...
}
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namespace
UnitTestDemo;
use
phpmock\phpunit\PHPMock;
class
DemoTest
extends
\PHPUnit_Framework_TestCase
{
use
PHPMock;
//
...
}
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namespace
UnitTestDemo;
use
phpmock\phpunit\PHPMock;
class
DemoTest
extends
\PHPUnit_Framework_TestCase
{
use
PHPMock;
//
...
}
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Testing demo_get_option
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class
DemoTest
extends
\PHPUnit_Framework_TestCase
{
public
function
test_demo_get_option()
{
$this-‐>assertEquals('bar',
demo_get_option('foo'));
}
}
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class
DemoTest
extends
\PHPUnit_Framework_TestCase
{
public
function
test_demo_get_option()
{
$this-‐>assertEquals('bar',
demo_get_option('foo'));
}
}
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class
DemoTest
extends
\PHPUnit_Framework_TestCase
{
public
function
test_demo_get_option()
{
$this-‐>assertEquals('bar',
demo_get_option('foo'));
}
}
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class
DemoTest
extends
\PHPUnit_Framework_TestCase
{
public
function
test_demo_get_option()
{
$this-‐>assertEquals('bar',
demo_get_option('foo'));
}
}
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class
DemoTest
extends
\PHPUnit_Framework_TestCase
{
public
function
test_demo_get_option()
{
$this-‐>assertEquals('bar',
demo_get_option('foo'));
}
}
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Let's try to run it
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No content
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Oops, that didn’t work!
(Why is that?)
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Missing test double
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class
DemoTest
extends
\PHPUnit_Framework_TestCase
{
public
function
test_demo_get_option()
{
$get_option
=
$this-‐>getFunctionMock(
'UnitTestDemo',
'get_option'
);
$this-‐>assertEquals('bar',
demo_get_option('foo'));
}
}
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What’s a mock?
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Type of test double
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Simulates the behaviour
of a function or object
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Verifies how
you interact with it
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Only type of test double
that does that
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class
DemoTest
extends
\PHPUnit_Framework_TestCase
{
public
function
test_demo_get_option()
{
$get_option
=
$this-‐>getFunctionMock(
'UnitTestDemo',
'get_option'
);
$get_option-‐>expects($this-‐>once())
-‐>with($this-‐>equalTo('demo_foo'))
-‐>willReturn('bar');
$this-‐>assertEquals('bar',
demo_get_option('foo'));
}
}
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class
DemoTest
extends
\PHPUnit_Framework_TestCase
{
public
function
test_demo_get_option()
{
$get_option
=
$this-‐>getFunctionMock(
'UnitTestDemo',
'get_option'
);
$get_option-‐>expects($this-‐>once())
-‐>with($this-‐>equalTo('demo_foo'))
-‐>willReturn('bar');
$this-‐>assertEquals('bar',
demo_get_option('foo'));
}
}
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class
DemoTest
extends
\PHPUnit_Framework_TestCase
{
public
function
test_demo_get_option()
{
$get_option
=
$this-‐>getFunctionMock(
'UnitTestDemo',
'get_option'
);
$get_option-‐>expects($this-‐>once())
-‐>with($this-‐>equalTo('demo_foo'))
-‐>willReturn('bar');
$this-‐>assertEquals('bar',
demo_get_option('foo'));
}
}
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class
DemoTest
extends
\PHPUnit_Framework_TestCase
{
public
function
test_demo_get_option()
{
$get_option
=
$this-‐>getFunctionMock(
'UnitTestDemo',
'get_option'
);
$get_option-‐>expects($this-‐>once())
-‐>with($this-‐>equalTo('demo_foo'))
-‐>willReturn('bar');
$this-‐>assertEquals('bar',
demo_get_option('foo'));
}
}
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No content
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Our first passing test!
(Yay!)
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Questions?
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Pushing things further
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Common to store an
array inside an option
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Except you might not
always get an array back
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You’ll often see (array)
next to get_option
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Let’s make our function
do this for us
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But let’s do it in reverse
(plot twist!)
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Start with a failing test
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Gives you a taste for
test-driven development
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First, a small change to
demo_get_option
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namespace
UnitTestDemo;
/**
*
Get
a
plugin
option
from
the
WordPress
database.
*
*
@param
string
$name
*
@param
mixed
$default
*
*
@return
mixed
*/
function
demo_get_option($name,
$default
=
null)
{
return
get_option('demo_'
.
$name,
$default);
}
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Update our test as well
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class
DemoTest
extends
\PHPUnit_Framework_TestCase
{
public
function
test_demo_get_option()
{
$get_option
=
$this-‐>getFunctionMock(
'UnitTestDemo',
'get_option'
);
$get_option-‐>expects($this-‐>once())
-‐>with(
$this-‐>equalTo('demo_foo'),
$this-‐>identicalTo(null)
)
-‐>willReturn('bar');
$this-‐>assertEquals('bar',
demo_get_option('foo'));
}
}
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identicalTo()
equalTo()
VS
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Creating our failing test
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class
DemoTest
extends
\PHPUnit_Framework_TestCase
{
public
function
test_demo_get_option_casts_array()
{
$get_option
=
$this-‐>getFunctionMock(
'UnitTestDemo',
'get_option'
);
$get_option-‐>expects($this-‐>once())
-‐>with(
$this-‐>equalTo('demo_foo'),
$this-‐>identicalTo(array())
)
-‐>willReturn('bar');
$this-‐>assertEquals(
array('bar'),
demo_get_option('foo',
array())
);
}
}
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Similar to our other test
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Changing inputs, outputs
and expected values
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class
DemoTest
extends
\PHPUnit_Framework_TestCase
{
public
function
test_demo_get_option_casts_array()
{
$get_option
=
$this-‐>getFunctionMock(
'UnitTestDemo',
'get_option'
);
$get_option-‐>expects($this-‐>once())
-‐>with(
$this-‐>equalTo('demo_foo'),
$this-‐>identicalTo(array())
)
-‐>willReturn('bar');
$this-‐>assertEquals(
array('bar'),
demo_get_option('foo',
array())
);
}
}
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class
DemoTest
extends
\PHPUnit_Framework_TestCase
{
public
function
test_demo_get_option_casts_array()
{
$get_option
=
$this-‐>getFunctionMock(
'UnitTestDemo',
'get_option'
);
$get_option-‐>expects($this-‐>once())
-‐>with(
$this-‐>equalTo('demo_foo'),
$this-‐>identicalTo(array())
)
-‐>willReturn('bar');
$this-‐>assertEquals(
array('bar'),
demo_get_option('foo',
array())
);
}
}
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No content
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Let’s get the test to pass
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namespace
UnitTestDemo;
/**
*
Get
a
plugin
option
from
the
WordPress
database.
*
*
@param
string
$name
*
@param
mixed
$default
*
*
@return
mixed
*/
function
demo_get_option($name,
$default
=
null)
{
$option
=
get_option('demo_'
.
$name,
$default);
if
(is_array($default)
&&
!is_array($option))
{
$option
=
(array)
$option;
}
return
$option;
}
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No content
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And there you go!
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Questions?
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Building your
testing habit
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A test, by itself, feels
pretty insignificant
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Just one loop in your
safety net
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You need more than one
for them to support you
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Testing is a lot like
picking up a new habit
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Hard to stay motivated
(Chips are soooo tasty!)
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https://github.com/carlalexander/wordpress-unit-test-demo
Ready to start?
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Thank you!