Sudar Muthu | @sudarmuthu #WCPune
Unit Testing For
WordPress
WordCamp Pune, 2015
Sudar Muthu
http://sudarmuthu.com
https://github.com/sudar

Sudar Muthu | @sudarmuthu #WCPune
Me
• Programming in PHP for more than a decade and in
WordPress for about 8 years.
• Big fan of automating process and workflows.
• Contributor to a couple of open source projects.
• Remote worker at 10up (and yes 10up is hiring :) )

Sudar Muthu | @sudarmuthu #WCPune
What about you?
• What is your typical development environment?
• What is your experience with PHP and WordPress?
• What is your experience with Unit Testing?
• What are your expectations out of this talk?

Sudar Muthu | @sudarmuthu #WCPune
Unit Testing
Credit: https://twitter.com/alistratov/status/599109195548459009

Sudar Muthu | @sudarmuthu #WCPune
Is there something wrong?
class Sample {
protected $value;
public function initialise($value) {
$this->value = $value;
}
public function execute() {
if (!$this->value) {
throw new Exception("value not set");
}
return $value * 10; // business logic
}
}
$sample = new Sample;
$sample->execute();

Sudar Muthu | @sudarmuthu #WCPune
Finding bugs is not
easy

Sudar Muthu | @sudarmuthu #WCPune
Write Tests

Sudar Muthu | @sudarmuthu #WCPune
Write Tests
It sounds obvious but getting started is the hardest part!

Sudar Muthu | @sudarmuthu #WCPune
Different types of Testing
• Functionality testing
• Integration testing
• Unit testing

Sudar Muthu | @sudarmuthu #WCPune
Different types of Testing
• Functionality testing
• Integration testing
• Unit testing

Sudar Muthu | @sudarmuthu #WCPune
Briefly
• What is PHPUnit?
• Installing PHPUnit
• Setting up folder structure
• phpunit.xml

Sudar Muthu | @sudarmuthu #WCPune
Three steps in test cases
• setup
• act
• verify

Sudar Muthu | @sudarmuthu #WCPune
Demo

Sudar Muthu | @sudarmuthu #WCPune
Writing our first test case
public function test_execute_works_with_initialise() {
// setup
$sample = new Sample();
// act
$sample->initialise(10);
$return = $sample->execute();
// verify
$this->assertEquals(100, $return);
}

Sudar Muthu | @sudarmuthu #WCPune
Testing Exception
/**
* @expectedException Exception
*/
public function test_execute_needs_initialise() {
// setup
$sample = new Sample();
// act
$sample->execute();
// verify
// that it throws and exception
}

Sudar Muthu | @sudarmuthu #WCPune
Let’s add more tests
• Testing decimals
• Testing with negative values
• Testing it work with zero

Sudar Muthu | @sudarmuthu #WCPune
Unit Testing
WordPress Code

Sudar Muthu | @sudarmuthu #WCPune
What should be tested?
function my_permalink_function( $post_id ) {
$permalink = get_permalink( absint( $post_id ) );
$permalink = apply_filters( 'special_filter', $permalink );
do_action( 'special_action', $permalink );
return $permalink;
}

Sudar Muthu | @sudarmuthu #WCPune
Don’t test the WordPress
built-in function

Sudar Muthu | @sudarmuthu #WCPune
Don’t test the WordPress
built-in function
Use Mocks instead
https://github.com/10up/wp_mock

Sudar Muthu | @sudarmuthu #WCPune
Mocking WordPress function
WP_Mock::wpFunction( 'get_permalink', array(
'args' => 42,
'times' => 1,
'return' => 'http://example.com/foo'
) );

Sudar Muthu | @sudarmuthu #WCPune
Mocking WordPress filter
WP_Mock::onFilter( 'special_filter' )
->with( 'http://example.com/foo' )
->reply( 'https://example.com/bar' );

Sudar Muthu | @sudarmuthu #WCPune
Mocking WordPress action
WP_Mock::expectAction(
'special_action',
'https://example.com/bar'
);

Sudar Muthu | @sudarmuthu #WCPune
Putting it all together
public function test_my_permalink_function() {
WP_Mock::wpFunction( 'get_permalink', array(
'args' => 42,
'times' => 1,
'return' => 'http://example.com/foo'
) );
WP_Mock::wpPassthruFunction( 'absint', array( 'times' => 1 ) );
WP_Mock::onFilter( 'special_filter' )
->with( 'http://example.com/foo' )
->reply( 'https://example.com/bar' );
WP_Mock::expectAction( 'special_action', 'https://example.com/bar' );
$result = my_permalink_function( 42 );
$this->assertEquals( 'https://example.com/bar', $result );
}

Sudar Muthu | @sudarmuthu #WCPune
Some PHPUnit Tips
• Have a fast test suite
• Use Composer
• Enable code coverage in reports
• phpunit.xml.dist vs phpunit.xml
• Use specific assertions
• Check out Unit tests in WordPress core

Sudar Muthu | @sudarmuthu #WCPune
WordPress plugin
skeleton with Tests
Use yo generator
https://github.com/10up/generator-wp-make

Sudar Muthu | @sudarmuthu #WCPune
Thank You
@sudarmuthu
http://sudarmuthu.com
https://github.com/sudar