Adding DOMDocument property names to the ruleset

Alley-Interactive/ruleset.xml

@@ -95,4 +95,24 @@
   <rule ref="WordPress.Files.FileName.InvalidClassFileName">
     <exclude-pattern>tests/*Test.php</exclude-pattern>
   </rule>
+
+  <!-- Allow snakeCase for DOMDocument/DOMElement properties -->
+  <rule ref="WordPress.NamingConventions.ValidVariableName">
+    <properties>
+      <property name="allowed_custom_properties" type="array">
+        <element value="className"/>
+        <element value="childNodes"/>
+        <element value="firstChild"/>
+        <element value="formatOutput"/>
+        <element value="lastChild"/>
+        <element value="nodeName"/>
+        <element value="nodeType"/>
+        <element value="nodeValue"/>
+        <element value="parentNode"/>
+        <element value="preserveWhiteSpace"/>
+        <element value="tagName"/>
+        <element value="textContent"/>
+      </property>
+    </properties>
+  </rule>
 </ruleset>

CHANGELOG.md

@@ -7,6 +7,7 @@ This project adheres to [Keep a CHANGELOG](https://keepachangelog.com/en/1.0.0/)
 ### Unreleased
 
 - Allow PSR-4 style `ClassName.php` file names to support our migration to PSR-4 for test files.
+- Allow camelCase'd DOMDocument/DOMElement/etc. property names to not be flagged by `WordPress.NamingConventions.ValidVariableName`.
 
 ### 2.0.2
 

tests/fixtures/pass/dom.php

@@ -0,0 +1,28 @@
+<?php
+/**
+ * DOM Attributes test file.
+ *
+ * Ensure that DOMDocument/DOMElement/DOMNode attributes that are camelCase'd
+ * are not flagged by PHPCS.
+ *
+ * @package Alley\WP\Coding_Standards
+ */
+
+$ai_document = new DOMDocument();
+
+// Ensure that DOMDocument properties are allowed.
+$ai_document->preserveWhiteSpace = false;
+$ai_document->formatOutput       = true;
+
+$ai_document->loadHTML(
+	file_get_contents( 'https://www.alley.com' ) // phpcs:ignore
+);
+
+// Interact with the DOM document.
+$ai_element = $ai_document->getElementById( 'element-id' );
+
+// Ensure that DOMElement properties are allowed.
+$ai_element->textContent = 'Hello, world!';
+$ai_element->className   = 'element-class';
+
+$ai_tag = $ai_element->tagName;