Add non regression test

Author: VincentLanglet

tests/PHPStan/Rules/Properties/AccessPropertiesRuleTest.php

@@ -1068,6 +1068,14 @@ public function testTraitMixin(): void
 		$this->analyse([__DIR__ . '/data/trait-mixin.php'], []);
 	}
 
+	public function testBug9706(): void
+	{
+		$this->checkThisOnly = false;
+		$this->checkUnionTypes = true;
+		$this->checkDynamicProperties = true;
+		$this->analyse([__DIR__ . '/data/bug-9706.php'], []);
+	}
+
 	#[RequiresPhp('>= 8.4')]
 	public function testAsymmetricVisibility(): void
 	{

tests/PHPStan/Rules/Properties/data/bug-9706.php

@@ -0,0 +1,15 @@
+<?php declare(strict_types = 1);
+
+namespace BUg9706;
+
+class MissingDOMNamedNodeMapProperty
+{
+	public function test(): void
+	{
+		$node = new \DOMElement('div');
+		$attributes = $node->attributes;
+		// According to the php.net docs, $length should be a public read-only property.
+		// See https://www.php.net/manual/en/class.domnamednodemap.php
+		$length = $attributes->length;
+	}
+}