Magento2: Failed Override Magento_Tax module Class with protected method

Question

I am trying to override class Magento\Tax\Model\Sales\Total\Quote\CommonTaxCollector

I tried everything and checked the implementation is correct in di.xml

The method I am trying to override is a protected method processProductItems()

I have no clue what am I doing wrong here. It keeps calling the function from the original Magento_Tax class

di.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <preference for="Magento\Tax\Model\Sales\Total\Quote\CommonTaxCollector"
        type="Folio3\TaxCollector\Model\Sales\Total\Quote\CommonTaxCollector"/>
</config>

Override class Folio3\TaxCollector\Model\Sales\Total\Quote\CommonTaxCollector.php

class CommonTaxCollector extends \Magento\Tax\Model\Sales\Total\Quote\CommonTaxCollector
{
...

module.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
    <module name="Folio3_TaxCollector" setup_version="1.0.0">
        <sequence>
            <module name="Magento_Catalog"/>
            <module name="Magento_Checkout"/>
            <module name="Magento_Customer"/>
            <module name="Magento_Directory"/>
            <module name="Magento_User"/>
            <module name="Magento_Tax" />
        </sequence>
    </module>
</config>

Can anyone explain to me what am I doing wrong here? I think I have followed all the necessary steps. It keeps calling the original CommonTaxCollector.php class from Magento_Tax module

Answer 1

This is because you are overriding the wrong class.

Magento\Tax\Model\Sales\Total\Quote\CommonTaxCollector

The class CommonTaxCollector is not used directly, Magento2 used a Tax class which overrides the CommonTaxCollector class.

vendor/magento/module-tax/Model/Sales/Total/Quote/Tax.php

Tax.php

namespace Magento\Tax\Model\Sales\Total\Quote;
....

class Tax extends CommonTaxCollector {

Solution:

di.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <preference for="Magento\Tax\Model\Sales\Total\Quote\Tax"
        type="Folio3\TaxCollector\Model\Sales\Total\Quote\Tax"/>
</config>

Override class Folio3\TaxCollector\Model\Sales\Total\Quote\Tax.php

class Tax extends \Magento\Tax\Model\Sales\Total\Quote\Tax
{
...

It should work fine!