Decoupling Handlers 解耦处理函数

To get started, let's jump right into an example. Consider a queue handler that sends an SMS message to a user. After sending the message, the handler logs that message so we can keep a history of all SMS messages we have sent to that user. The code might look something like this:

接下来我们看一个例子。考虑有一个队列处理函数用来给用户发送手机短信。信息发送后，处理函数还要记录消息日志来保存给用户发送的消息历史。代码应该看起来是这样：

class SendSMS {
    public function fire($job, $data)
    {
        $twilio = new Twilio_SMS($apiKey);
        $twilio->sendTextMessage(array(
            'to'=> $data['user']['phone_number'],
            'message'=> $data['message'],
        ));
        $user = User::find($data['user']['id']);
        $user->messages()->create(array(
            'to'=> $data['user']['phone_number'],
            'message'=> $data['message'],
        ));
        $job->delete();
    }
}

Just by examining this class, you can probably spot several problems. First, it is hard to test. The Twilio_SMS class is instantiated inside of the fire method, meaning we will not be able to inject a mock service. Secondly, we are using Eloquent directly in the handler, thus creating a second testing problem as we will have to hit a real database to test this code. Finally, we are unable to send SMS messages outside of the queue. All of our SMS sending logic is tightly coupled to the Laravel queue.

简单审查下这个类，你可能会发现一些问题。首先，它难以测试。在 fire 方法里直接使用了 Twilio_SMS 类，意味着我们没法注入一个模拟的服务（译者注：即一旦测试则必须发送一条真实的短信）。第二，我们直接使用了 Eloquent，导致在测试时肯定会对数据库造成影响。第三，我们没法在队列外面发送短信，想在队列外面发还要重写一遍代码。也就是说我们的短信发送逻辑和 Laravel 的队列耦合太多了。

By extracting this logic into a separate "service" class, we can decouple our application's SMS sending logic from Laravel's queue. This will allow us to send SMS messages from anywhere in our application. While we are decoupling this process from the queue, we will also refactor it to be more testable.

将里面的逻辑抽出成为一个单独的“服务”类，我们即可将短信发送逻辑和 Laravel 的队列解耦。这样我们就可以在应用的任何位置发送短信了。我们将其解耦的过程，也令其变得更易于测试。

So, let's examine an alternative:

那么我们来稍微改一改：

class User extends Eloquent {
    /**
     * Send the User an SMS message
     *
     * @param SmsCourierInterface $courier
     * @param string $message
     * @return SmsMessage
     */
    public function sendSmsMessage(SmsCourierInterface $courier, $message)
    {
        $courier->sendMessage($this->phone_number, $message);
        return $this->sms()->create(array(
            'to'=> $this->phone_number,
            'message'=> $message,
        ));
    }
}

In this refactored example, we have extracted the SMS sending logic into the User model. We are also injecting a SmsCourierInterface implementation into the method, allowing us to better test that aspect of the process. Now that we have refactored this logic, let's re-write our queue handler:

在本重构的例子中，我们将短信发送逻辑抽出到 User 模型里。同时我们将 SmsCourierInterface 的实现注入到该方法里，这样我们可以更容易对该方法进行测试。现在我们已经重构了短信发送逻辑，让我们再重写队列处理函数：

class SendSMS {
    public function __construct(UserRepository $users, SmsCourierInterface $courier)
    {
        $this->users = $users;
        $this->courier = $courier;
    }
    public function fire($job, $data)
    {
        $user = $this->users->find($data['user']['id']);
        $user->sendSmsMessage($this->courier, $data['message']);
        $job->delete();
    }
}

As you can see in this refactored example, our queue handler is now much lighter. It essentially serves as a translation layer between the queue and your real application logic. That is great! It means that we can easily send SMS message s outside of the queue context. Finally, let's write some tests for our SMS sending logic:

你可以看到我们重构了代码，使得队列处理函数更轻量化了。它本质上变成了队列系统和你真正的业务逻辑之间的转换层。这可是很了不起！这意味着我们可以很轻松的脱离队列系统来发送短信息。最后，让我们为短信发送逻辑写一些测试代码：

class SmsTest extends PHPUnit_Framework_TestCase {
    public function testUserCanBeSentSmsMessages()
    {
        /**
         * Arrage ...
         */
        $user = Mockery::mock('User[sms]');
        $relation = Mockery::mock('StdClass');
        $courier = Mockery::mock('SmsCourierInterface');

        $user->shouldReceive('sms')->once()->andReturn($relation);

        $relation->shouldReceive('create')->once()->with(array(
            'to' => '555-555-5555',
            'message' => 'Test',
        ));

        $courier->shouldReceive('sendMessage')->once()->with(
            '555-555-5555', 'Test'
        );

        /**
         * Act ...
         */
        $user->sms_number = '555-555-5555'; //译者注： 应当为 phone_number
        $user->sendMessage($courier, 'Test');
    }
}