Add custom checkout address validator

Question

for our customer I've to create a custom validation for a field in the shipping-address-fieldset. For that I've created a custom module in /app/code. The js requirement works but the validation doesn't appear. Here is what I've got (anonymised):

/app/code/[Vendor]/[Module]/view/frontend/requirejs-config.js

var config = {
    config: {
        mixins: {
            'mage/validation': {
                '[Vendor]_[Module]/js/test-mixin': true
            }
        }
    }
}

/app/code/[Vendor]/[Module]/view/frontend/web/js/test-mixin.js

define([
    'jquery',
    'jquery/ui',
    'jquery/validate',
    'mage/translate'
], function($) {
    'use strict';

    return function(){
        $.validator.addMethod(
            // validator name
            'validate-five-words',
            // validator check function
            function(value, element){
                return value.split(' ').length == 5;
            },
            // error message
            $.mage.__('Please enter exactly five words')
        );
    };
    
});

and I've tried to add the validator to the company field in checkout_index_index.xml

<item name="company" xsi:type="array">
    <item name="validation" xsi:type="array">
        <item name="required-entry" xsi:type="boolean">true</item>
        <item name="validate-five-words" xsi:type="boolean">true</item>
    </item>
</item>

The required-entry validation and others like validate-street are working correctly. May be it's the wrong mixin hook or I miss something else.

Answer 1

app/code/[Vendor]/[Module]/view/frontend

requirejs-config.js

var config = {
    config: {
        mixins: {
            'Magento_Ui/js/lib/validation/validator': {
                'Namespace_Modulename/js/test-mixin': true
            }
        }
    }
}

app/code/[Vendor]/[Module]/view/frontend/web/js

test-mixin.js

define(
    ['jquery'],
   function($) {
  "use strict";
    return function(validator) {
        validator.addRule(
            'validate-five-words',
                function(value, element) { 
                    return value.split(' ').length == 5;
                },
            $.mage.__('If any Error then put here the Message')
        );
        return validator;
    }
});

I Hope This Helps You.