Move SendingQueueEntity::toArray() to SendingQueuesResponseBuilder::build()

Based on a suggestion during the review of the PR, it was decided that
it makes more sense for the code that was created as
SendingQueueEntity::toArray() tp be moved to
SendingQueuesResponseBuilder::build(). It is used only to build the
format that is send in the API response.

[MAILPOET-4368]

mailpoet/tests/integration/API/JSON/ResponseBuilders/SendingQueuesResponseBuilderTest.php

@@ -0,0 +1,66 @@
+<?php declare(strict_types = 1);
+
+namespace integration\API\JSON\ResponseBuilders;
+
+use MailPoet\API\JSON\ResponseBuilders\SendingQueuesResponseBuilder;
+use MailPoet\Entities\NewsletterEntity;
+use MailPoet\Entities\ScheduledTaskEntity;
+use MailPoet\Entities\SendingQueueEntity;
+use MailPoet\Tasks\Sending;
+use MailPoet\Test\DataFactories\Newsletter as NewsletterFactory;
+use MailPoet\Test\DataFactories\ScheduledTask as ScheduledTaskFactory;
+use MailPoet\Test\DataFactories\SendingQueue as SendingQueueFactory;
+use MailPoetVendor\Carbon\Carbon;
+
+class SendingQueuesResponseBuilderTest extends \MailPoetTest {
+  /** @var NewsletterEntity */
+  private $newsletter;
+
+  /** @var ScheduledTaskEntity */
+  private $scheduledTask;
+
+  /** @var SendingQueueEntity */
+  private $sendingQueue;
+
+  /** @var SendingQueuesResponseBuilder */
+  private $sendingQueuesResponseBuilder;
+
+  public function _before() {
+    $newsletterFactory = new NewsletterFactory();
+    $sendingQueueFactory = new SendingQueueFactory();
+    $scheduledTaskFactory = new ScheduledTaskFactory();
+
+    $this->sendingQueuesResponseBuilder = $this->diContainer->get(SendingQueuesResponseBuilder::class);
+    $scheduledAt = new Carbon('2018-10-10 10:00:00');
+    $this->newsletter = $newsletterFactory->create();
+    $this->scheduledTask = $scheduledTaskFactory->create(Sending::TASK_TYPE, ScheduledTaskEntity::STATUS_SCHEDULED, $scheduledAt);
+    $this->sendingQueue = $sendingQueueFactory->create($this->scheduledTask, $this->newsletter);
+    $this->assertInstanceOf(SendingQueueEntity::class, $this->sendingQueue);
+  }
+
+  public function testBuildReturnsExpectedResult() {
+    $expectedResult = [
+      'id' => $this->sendingQueue->getId(),
+      'type' => 'sending',
+      'status' => 'scheduled',
+      'priority' => 0,
+      'scheduled_at' => '2018-10-10 10:00:00',
+      'processed_at' => null,
+      'created_at' => !is_null($this->sendingQueue->getCreatedAt()) ? $this->sendingQueue->getCreatedAt()->format('Y-m-d H:i:s') : null,
+      'updated_at' => $this->sendingQueue->getUpdatedAt()->format('Y-m-d H:i:s'),
+      'deleted_at' => null,
+      'in_progress' => null,
+      'reschedule_count' => 0,
+      'meta' => null,
+      'task_id' => $this->scheduledTask->getId(),
+      'newsletter_id' => $this->newsletter->getId(),
+      'newsletter_rendered_body' => null,
+      'newsletter_rendered_subject' => null,
+      'count_total' => 0,
+      'count_processed' => 0,
+      'count_to_process' => 0,
+    ];
+
+    $this->assertSame($expectedResult, $this->sendingQueuesResponseBuilder->build($this->sendingQueue));
+  }
+}