ENGCOM-2269: [Forwardport] Customer group extension attributes not carried over on save #16666

 - Merge Pull Request #16666 from mageprince/magento2:2.3-develop-PR-port-16254
 - Merged commits:
   1. 0fdc3f7
   2. ce513d2
   3. b89430f
   4. c938472
   5. e59beac
   6. 0b62554
   7. 3c632b5

Author: magento-engcom-team

app/code/Magento/Customer/Model/ResourceModel/GroupRepository.php

@@ -156,6 +156,11 @@ public function save(\Magento\Customer\Api\Data\GroupInterface $group)
             ->setCode($groupModel->getCode())
             ->setTaxClassId($groupModel->getTaxClassId())
             ->setTaxClassName($groupModel->getTaxClassName());
+
+        if ($group->getExtensionAttributes()) {
+            $groupDataObject->setExtensionAttributes($group->getExtensionAttributes());
+        }
+
         return $groupDataObject;
     }
 

app/code/Magento/Customer/Test/Unit/Model/ResourceModel/GroupRepositoryTest.php

@@ -38,6 +38,11 @@ class GroupRepositoryTest extends \PHPUnit\Framework\TestCase
      */
     protected $group;
 
+    /**
+     * @var \Magento\Customer\Api\Data\GroupInterface|\PHPUnit_Framework_MockObject_MockObject
+     */
+    protected $factoryCreatedGroup;
+
     /**
      * @var \Magento\Customer\Model\ResourceModel\Group|\PHPUnit_Framework_MockObject_MockObject
      */
@@ -153,6 +158,12 @@ private function setupGroupObjects()
             'group',
             false
         );
+        $this->factoryCreatedGroup = $this->getMockForAbstractClass(
+            \Magento\Customer\Api\Data\GroupInterface::class,
+            [],
+            'group',
+            false
+        );
 
         $this->groupResourceModel = $this->createMock(\Magento\Customer\Model\ResourceModel\Group::class);
     }
@@ -162,16 +173,22 @@ public function testSave()
         $groupId = 0;
 
         $taxClass = $this->getMockForAbstractClass(\Magento\Tax\Api\Data\TaxClassInterface::class, [], '', false);
+        $extensionAttributes = $this->getMockForAbstractClass(
+            \Magento\Customer\Api\Data\GroupExtensionInterface::class
+        );
 
-        $this->group->expects($this->once())
+        $this->group->expects($this->atLeastOnce())
             ->method('getCode')
             ->willReturn('Code');
         $this->group->expects($this->atLeastOnce())
             ->method('getId')
             ->willReturn($groupId);
-        $this->group->expects($this->once())
+        $this->group->expects($this->atLeastOnce())
             ->method('getTaxClassId')
             ->willReturn(17);
+        $this->group->expects($this->atLeastOnce())
+            ->method('getExtensionAttributes')
+            ->willReturn($extensionAttributes);
 
         $this->groupModel->expects($this->atLeastOnce())
             ->method('getId')
@@ -185,22 +202,33 @@ public function testSave()
         $this->groupModel->expects($this->atLeastOnce())
             ->method('getTaxClassName')
             ->willReturn('Tax class name');
-        $this->group->expects($this->once())
+
+        $this->factoryCreatedGroup->expects($this->once())
             ->method('setId')
             ->with($groupId)
             ->willReturnSelf();
-        $this->group->expects($this->once())
+        $this->factoryCreatedGroup->expects($this->once())
             ->method('setCode')
             ->with('Code')
             ->willReturnSelf();
-        $this->group->expects($this->once())
+        $this->factoryCreatedGroup->expects($this->once())
             ->method('setTaxClassId')
             ->with(234)
             ->willReturnSelf();
-        $this->group->expects($this->once())
+        $this->factoryCreatedGroup->expects($this->once())
             ->method('setTaxClassName')
             ->with('Tax class name')
             ->willReturnSelf();
+        $this->factoryCreatedGroup->expects($this->once())
+            ->method('setExtensionAttributes')
+            ->with($extensionAttributes)
+            ->willReturnSelf();
+        $this->factoryCreatedGroup->expects($this->atLeastOnce())
+            ->method('getCode')
+            ->willReturn('Code');
+        $this->factoryCreatedGroup->expects($this->atLeastOnce())
+            ->method('getTaxClassId')
+            ->willReturn(17);
 
         $this->taxClassRepository->expects($this->once())
             ->method('get')
@@ -229,9 +257,12 @@ public function testSave()
             ->with($groupId);
         $this->groupDataFactory->expects($this->once())
             ->method('create')
-            ->willReturn($this->group);
+            ->willReturn($this->factoryCreatedGroup);
+
+        $updatedGroup = $this->model->save($this->group);
 
-        $this->assertSame($this->group, $this->model->save($this->group));
+        $this->assertSame($this->group->getCode(), $updatedGroup->getCode());
+        $this->assertSame($this->group->getTaxClassId(), $updatedGroup->getTaxClassId());
     }
 
     /**