ENGCOM-3086: Fix/add expresion #17915

 - Merge Pull Request #17915 from magently/magento2:fix/addExpresion
 - Merged commits:
   1. e9451e0
   2. 29680f7
   3. 5a702ef

Author: magento-engcom-team

lib/internal/Magento/Framework/Model/ResourceModel/Db/Collection/AbstractCollection.php

@@ -346,7 +346,9 @@ public function addExpressionFieldToSelect($alias, $expression, $fields)
             $fullExpression = str_replace('{{' . $fieldKey . '}}', $fieldItem, $fullExpression);
         }
 
-        $this->getSelect()->columns([$alias => $fullExpression]);
+        $fullExpression = new \Zend_Db_Expr($fullExpression);
+        $this->_fieldsToSelect[$alias] = $fullExpression;
+        $this->_fieldsToSelectChanged = true;
 
         return $this;
     }

lib/internal/Magento/Framework/Model/Test/Unit/ResourceModel/Db/Collection/AbstractCollectionTest.php

@@ -269,8 +269,9 @@ public function addFieldToSelectDataProvider()
      */
     public function testAddExpressionFieldToSelect($alias, $expression, $fields, $expected)
     {
-        $this->selectMock->expects($this->once())->method('columns')->with($expected);
         $this->assertTrue($this->uut->addExpressionFieldToSelect($alias, $expression, $fields) instanceof Uut);
+        $this->assertEquals($expected, $this->uut->getFieldsToSelect());
+        $this->assertTrue($this->uut->wereFieldsToSelectChanged());
     }
 
     /**