AC-9340::Error occurs during Region id Processing while multi-shipping checkout

Author: ashishkumarpundeer

app/code/Magento/Catalog/Test/Unit/Controller/Adminhtml/Product/Attribute/GetRegionIdTest.php

@@ -454,7 +454,7 @@ public function getRegionId()
                 (string)$this->getCountryId()
             );
             if (empty($regionId)) {
-                return $this->getData('region_id');
+                $regionId = $this->getData('region_id');
             }
             $this->setData('region_id', $regionId);
         }

app/code/Magento/Customer/Model/Address/AbstractAddress.php

@@ -162,6 +162,24 @@ public function testGetRegionCodeWithRegionId()
         $this->assertEquals('UK', $this->model->getRegionCode());
     }
 
+
+    public function testGetRegionId()
+    {
+        $this->model->setData('region_id', 0);
+        $this->model->setData('region', '');
+        $this->model->setData('country_id', 'GB');
+        $region = $this->getMockBuilder(Region::class)
+            ->addMethods(['getCountryId', 'getCode'])
+            ->onlyMethods(['__wakeup', 'load', 'loadByCode','getId'])
+            ->disableOriginalConstructor()
+            ->getMock();
+        $region->method('loadByCode')
+            ->willReturnSelf();
+        $this->regionFactoryMock->method('create')
+            ->willReturn($region);
+        $this->assertEquals(0, $this->model->getRegionId());
+    }
+
     public function testGetRegionCodeWithRegion()
     {
         $countryId = 2;