PHPUnit test if class methods were called - phpunit

Question

I have model class that calls mailer class inside one of its methods:
class someModel{
public function sendEmail($data){
$mailer = new Mailer();
$mailer->setFrom($data['from']);
$mailer->setTo($data['to']);
$mailer->setSubject($data['subject']);
return $mailer->send();
}
}
How can I test sendEmail method? Maybe I should mock mailer class and check if all these mailer methods were called in sendMail method?
Your help would be appreciated.

Answer 1

IMO wrapping the Mailer class does not solve the problem you're facing, which is you don't have control over the Mail instance being used.
The problem comes from creating the dependencies inside the object that needs them instead of injecting them externally like this:
class someModel{
private $mailer;
public function __construct(Mailer $mailer) {
$this->mailer = $mailer;
}
public function sendEmail($data){
$this->mailer->setFrom($data['from']);
$this->mailer->setTo($data['to']);
$this->mailer->setSubject($data['subject']);
return $this->mailer->send();
}
}
When creating the someModel instance, you must pass a Mail instance (which is an external dependency). And in the test you can pass a Mail mock that will check that the correct calls are being made.
Alternative:
If you feel that injecting a Mail instance is bad (maybe because there are lots of someModel instances), or you just can't change your code this way, then you could use a Services repository, that will keep a single Mail instance and that allows you to set it externally (again, in the test you would set a mock).
Try a simple one like Pimple.

Answer 2

I would (and have in my own code with Mailer!) wrap your instance of Mailer inside a class that you write. In other words, make your own Email class that uses Mailer under the hood. That allows you to simplify the interface of Mailer down to just what you need and more easily mock it. It also gives you the ability to replace Mailer seamlessly at a later date.
The most important thing to keep in mind when you wrap classes to hide external dependencies is keep the wrapper class simple. It's only purpose is to let you swap out the Email libraries class, not provide any complicated logic.
Example:
class Emailer {
private $mailer = new Mailer();
public function send($to, $from, $subject, $data) {
$this->mailer->setFrom($from);
$this->mailer->setTo($to);
...
return $mailer->send();
}
}
class EmailerMock extends Emailer {
public function send($to, $from, $subject, $data) {
... Store whatever test data you want to verify ...
}
//Accessors for testing the right data was sent in your unit test
public function getTo() { ... }
...
}
I follow the same pattern for all classes/libraries that want to touch things external to my software. Other good candidates are database connections, web services connections, cache connections, etc.
EDIT:
gontrollez raised a good point in his answer about dependency injection. I failed to explicitly mention it, but after creating the wrapper the way you would want to use some form of dependency injection to get it into the code where you want to use it. Passing in the instance makes it possible to setup the test case with a Mocked instance.
One method of doing this is passing in the instance to the constructor as gontrollez recommends. There are a lot of cases where that is the best way to do it. However, for "external services" that I am mocking I found that method became tedious because so many classes ended up needing the instance passed in. Consider for example a database driver that you want to Mock for your tests, but you use in many many different classes. So instead what I do is create a singleton class with a method that lets me mock the whole thing at once. Any client code can then just use the singleton to get access to a service without knowing that it was mocked. It looked something like this:
class Externals {
static private $instance = null;
private $db = null;
private $email = null;
...
private function __construct() {
$this->db = new RealDB();
$this->mail = new RealMail();
}
static function initTest() {
self::get(); //Ensure instance created
$db = new MockDB();
$email = new MockEmail();
}
static function get() {
if(!self::$instance)
self::$instance = new Externals();
return self::$instance;
}
function getDB() { return $this->db; }
function getMail() { return $this->mail; }
....
}
Then you can use phpunit's bootstrap file feature to call Externals::initTest() and all your tests will be setup with the mocked externals!

Answer 3

First, as RyanW says, you should write your own wrapper for Mailer.
Second, to test it, use a mock:
<?php
class someModelTest extends \PHPUnit_Framework_TestCase
{
public function testSendEmail()
{
// Mock the class so we can verify that the methods are called
$model = $this->getMock('someModel', array('setFrom', 'setTo', 'setSubject', 'send'));
$controller->expects($this->once())
->method('setFrom');
$controller->expects($this->once())
->method('setTo');
$controller->expects($this->once())
->method('setSubject');
$controller->expects($this->once())
->method('send');
$model->sendEmail();
}
}
The above code is untested, but it basically mocks the someModel class, creating dummy functions for each each function called within sendEmail. It then tests to make sure each of the functions called by sendEmail is called exactly once when sendEmail is called.
See the PHPUnit docs for more info on mocking.