Fetch only subscribed recipients when sending a newsletter

[MAILPOET-4166]

mailpoet/lib/Cron/Workers/SendingQueue/SendingQueue.php

@@ -185,7 +185,7 @@ class SendingQueue {
       if (!empty($newsletterSegmentsIds[0])) {
         // Check that subscribers are in segments
         $foundSubscribersIds = $this->subscribersFinder->findSubscribersInSegments($subscribersToProcessIds, $newsletterSegmentsIds);
-        $foundSubscribers = SubscriberModel::whereIn('id', $subscribersToProcessIds)
+        $foundSubscribers = empty($foundSubscribersIds) ? [] : SubscriberModel::whereIn('id', $foundSubscribersIds)
           ->whereNull('deleted_at')
           ->findMany();
       } else {

mailpoet/tests/integration/Cron/Workers/SendingQueue/SendingQueueTest.php

@@ -59,6 +59,7 @@ class SendingQueueTest extends \MailPoetTest {
   public $sendingQueueWorker;
   public $cronHelper;
   public $newsletterLink;
+  /* @var SendingTask */
   public $queue;
   public $newsletterSegment;
   public $newsletter;
@@ -706,6 +707,44 @@ class SendingQueueTest extends \MailPoetTest {
     expect($updatedQueue->countToProcess)->equals(0);
   }
 
+  public function testItPreventsSendingNewsletterToRecipientWhoIsUnsubscribed() {
+    $subscriberFactory = new \MailPoet\Test\DataFactories\Subscriber();
+    $unsubscribedSubscriber = $subscriberFactory
+      ->withStatus(SubscriberEntity::STATUS_UNSUBSCRIBED)
+      ->create();
+    $this->queue->setSubscribers([
+      $this->subscriber->getId(), // subscriber that should be processed
+      $unsubscribedSubscriber->getId(), // subscriber that should be skipped
+    ]);
+    $sendingQueueWorker = $this->getSendingQueueWorker(
+      null,
+      Stub::make(
+        new MailerTask(),
+        [
+          'send' => Expected::exactly(1, function() {
+            return $this->mailerTaskDummyResponse;
+          }),
+        ],
+        $this
+      )
+    );
+    $sendingQueueWorker->process();
+
+    // queue status is set to completed
+    /** @var SendingQueue $updatedQueue */
+    $updatedQueue = SendingQueue::findOne($this->queue->id);
+    $updatedQueue = SendingTask::createFromQueue($updatedQueue);
+
+    // Unprocessable subscribers were removed
+    expect($updatedQueue->getSubscribers(ScheduledTaskSubscriber::STATUS_PROCESSED))
+      ->equals([
+          $this->subscriber->getId(), // subscriber that should be processed
+      ]);
+    expect($updatedQueue->countTotal)->equals(1);
+    expect($updatedQueue->countProcessed)->equals(1);
+    expect($updatedQueue->countToProcess)->equals(0);
+  }
+
   public function testItRemovesNonexistentSubscribersFromProcessingList() {
     $queue = $this->queue;
     $queue->setSubscribers([