diff --git a/WordPress/Tests/NamingConventions/PrefixAllGlobalsUnitTest.1.inc b/WordPress/Tests/NamingConventions/PrefixAllGlobalsUnitTest.1.inc
index e63122d3..011e250b 100644
--- a/WordPress/Tests/NamingConventions/PrefixAllGlobalsUnitTest.1.inc
+++ b/WordPress/Tests/NamingConventions/PrefixAllGlobalsUnitTest.1.inc
@@ -137,7 +137,7 @@ class Acronym_Example {
 	function do_something( $param = 'default' ) {}
 }
 
-$acronym_class = new class {
+$acronym_class = new readonly class {
 	const SOME_CONSTANT = 'value';
 
 	public $var = 'abc';
diff --git a/WordPress/Tests/NamingConventions/ValidFunctionNameUnitTest.inc b/WordPress/Tests/NamingConventions/ValidFunctionNameUnitTest.1.inc
similarity index 96%
rename from WordPress/Tests/NamingConventions/ValidFunctionNameUnitTest.inc
rename to WordPress/Tests/NamingConventions/ValidFunctionNameUnitTest.1.inc
index 6a06ba3c..4fa7a05e 100644
--- a/WordPress/Tests/NamingConventions/ValidFunctionNameUnitTest.inc
+++ b/WordPress/Tests/NamingConventions/ValidFunctionNameUnitTest.1.inc
@@ -223,6 +223,11 @@ function lähtöaika() {} // OK.
 function lÄhtÖaika() {} // Bad, but only handled by the sniff if Mbstring is available.
 function lÄhtOaika() {} // Bad, handled via transliteration of non-ASCII chars if Mbstring is not available.
 
-// Live coding/parse error.
-// This has to be the last test in the file.
-function
+/*
+ * Safeguard that PHP 8.3+ readonly anonymous classes are handled correctly.
+ */
+$anon_class = new readonly class() {
+    public function camelCase() {} // Bad.
+    protected function __something() {} // Bad.
+    private function snake_case() {} // Ok.
+};
diff --git a/WordPress/Tests/NamingConventions/ValidFunctionNameUnitTest.2.inc b/WordPress/Tests/NamingConventions/ValidFunctionNameUnitTest.2.inc
new file mode 100644
index 00000000..4f73e110
--- /dev/null
+++ b/WordPress/Tests/NamingConventions/ValidFunctionNameUnitTest.2.inc
@@ -0,0 +1,8 @@
+<?php
+
+/*
+ * Intentional parse error (nothing after T_FUNCTION).
+ * This should be the only test in this file.
+ */
+
+function
diff --git a/WordPress/Tests/NamingConventions/ValidFunctionNameUnitTest.php b/WordPress/Tests/NamingConventions/ValidFunctionNameUnitTest.php
index 6dbd5e8c..349091a4 100644
--- a/WordPress/Tests/NamingConventions/ValidFunctionNameUnitTest.php
+++ b/WordPress/Tests/NamingConventions/ValidFunctionNameUnitTest.php
@@ -25,38 +25,48 @@ final class ValidFunctionNameUnitTest extends AbstractSniffUnitTest {
 	/**
 	 * Returns the lines where errors should occur.
 	 *
+	 * @param string $testFile The name of the file being tested.
+	 *
 	 * @return array<int, int> Key is the line number, value is the number of expected errors.
 	 */
-	public function getErrorList() {
-		return array(
-			3   => 1,
-			9   => 1,
-			13  => 1,
-			15  => 1,
-			79  => 2,
-			80  => 2,
-			81  => 2,
-			82  => 2,
-			83  => 2,
-			84  => 2,
-			85  => 2,
-			86  => 2,
-			87  => 2,
-			88  => 2,
-			89  => 2,
-			106 => 2,
-			116 => 1,
-			117 => 1,
-			157 => 2,
-			183 => 1,
-			184 => 1,
-			185 => 1,
-			199 => 1,
-			208 => 2,
-			210 => 1,
-			223 => function_exists( 'mb_strtolower' ) ? 1 : 0,
-			224 => 1,
-		);
+	public function getErrorList( $testFile = '' ) {
+		switch ( $testFile ) {
+			case 'ValidFunctionNameUnitTest.1.inc':
+				return array(
+					3   => 1,
+					9   => 1,
+					13  => 1,
+					15  => 1,
+					79  => 2,
+					80  => 2,
+					81  => 2,
+					82  => 2,
+					83  => 2,
+					84  => 2,
+					85  => 2,
+					86  => 2,
+					87  => 2,
+					88  => 2,
+					89  => 2,
+					106 => 2,
+					116 => 1,
+					117 => 1,
+					157 => 2,
+					183 => 1,
+					184 => 1,
+					185 => 1,
+					199 => 1,
+					208 => 2,
+					210 => 1,
+					223 => function_exists( 'mb_strtolower' ) ? 1 : 0,
+					224 => 1,
+					230 => 1,
+					231 => 1,
+				);
+
+			default:
+				return array();
+		}
 	}
 
 	/**