8022: Uncaught Error: Call to a member function addItem() on array in app/code/Magento/Sales/Model/Order/Shipment.php(backport to 2.2)

app/code/Magento/Sales/Model/Order/Shipment.php

@@ -93,6 +93,11 @@ class Shipment extends AbstractModel implements EntityInterface, ShipmentInterfa
  */
  protected $orderRepository;
 
+ /**
+ * @var \Magento\Sales\Model\ResourceModel\Order\Shipment\Track\Collection|null
+ */
+ private $tracksCollection = null;
+
  /**
  * @param \Magento\Framework\Model\Context $context
  * @param \Magento\Framework\Registry $registry
@@ -331,16 +336,11 @@ public function addItem(\Magento\Sales\Model\Order\Shipment\Item $item)
  */
  public function getTracksCollection()
  {
- if (!$this->hasData(ShipmentInterface::TRACKS)) {
- $this->setTracks($this->_trackCollectionFactory->create()->setShipmentFilter($this->getId()));
-
- if ($this->getId()) {
- foreach ($this->getTracks() as $track) {
- $track->setShipment($this);
- }
- }
+ if ($this->tracksCollection === null) {
+ $this->tracksCollection = $this->_trackCollectionFactory->create()->setShipmentFilter($this->getId());
  }
- return $this->getTracks();
+
+ return $this->tracksCollection;
  }
 
  /**

app/code/Magento/Sales/Model/ResourceModel/Order/Shipment/Relation.php

@@ -62,8 +62,8 @@ public function processRelation(\Magento\Framework\Model\AbstractModel $object)
  $this->shipmentItemResource->save($item);
  }
  }
- if (null !== $object->getTracks()) {
- foreach ($object->getTracks() as $track) {
+ if (null !== $object->getTracksCollection()) {
+ foreach ($object->getTracksCollection() as $track) {
  $track->setParentId($object->getId());
  $this->shipmentTrackResource->save($track);
  }

app/code/Magento/Sales/Test/Unit/Model/ResourceModel/Order/Shipment/RelationTest.php

@@ -86,7 +86,8 @@ protected function setUp()
  'getId',
  'getItems',
  'getTracks',
- 'getComments'
+ 'getComments',
+ 'getTracksCollection',
  ]
  )
  ->getMock();
@@ -123,7 +124,7 @@ public function testProcessRelations()
  ->method('getComments')
  ->willReturn([$this->commentMock]);
  $this->shipmentMock->expects($this->exactly(2))
- ->method('getTracks')
+ ->method('getTracksCollection')
  ->willReturn([$this->trackMock]);
  $this->itemMock->expects($this->once())
  ->method('setParentId')

dev/tests/integration/testsuite/Magento/Sales/Model/Order/ShipmentTest.php

@@ -3,6 +3,7 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+
 namespace Magento\Sales\Model\Order;
 
 /**
@@ -47,4 +48,35 @@ public function testPackages()
  $shipment->load($shipment->getId());
  $this->assertEquals($packages, $shipment->getPackages());
  }
+
+ /**
+ * Check that getTracksCollection() always return collection instance.
+ *
+ * @magentoDataFixture Magento/Sales/_files/order.php
+ */
+ public function testAddTrack()
+ {
+ $objectManager = \Magento\TestFramework\Helper\Bootstrap::getObjectManager();
+
+ $order = $objectManager->create(\Magento\Sales\Model\Order::class);
+ $order->loadByIncrementId('100000001');
+
+ /** @var \Magento\Sales\Model\Order\Shipment $shipment */
+ $shipment = $objectManager->create(\Magento\Sales\Model\Order\Shipment::class);
+ $shipment->setOrder($order);
+
+ $shipment->addItem($objectManager->create(\Magento\Sales\Model\Order\Shipment\Item::class));
+ $shipment->save();
+
+ /** @var $track \Magento\Sales\Model\Order\Shipment\Track */
+ $track = $objectManager->get(\Magento\Sales\Model\Order\Shipment\Track::class);
+ $track->setNumber('Test Number')->setTitle('Test Title')->setCarrierCode('Test CODE');
+
+ $this->assertEmpty($shipment->getTracks());
+ $shipment->addTrack($track)->save();
+
+ //to empty cache
+ $shipment->setTracks(null);
+ $this->assertNotEmpty($shipment->getTracks());
+ }
 }