Account for strtok() consuming initial commas

plugins/auto-sizes/hooks.php

@@ -116,8 +116,8 @@ function auto_sizes_apply_tag_parser_updates( WP_HTML_Tag_Processor $processor )
  * @return bool True if the 'auto' keyword is present, false otherwise.
  */
 function auto_sizes_attribute_includes_valid_auto( string $sizes_attr ): bool {
-	$token = strtok( strtolower( $sizes_attr ), ',' );
-	return false !== $token && 'auto' === trim( $token, " \t\f\r\n" );
+	list( $first_size ) = explode( ',', $sizes_attr, 2 );
+	return 'auto' === strtolower( trim( $first_size, " \t\f\r\n" ) );
 }
 
 /**

plugins/auto-sizes/tests/test-auto-sizes.php

@@ -266,6 +266,10 @@ public function data_provider_to_test_auto_sizes_update_content_img_tag(): array
 				'input'    => '<img src="https://example.com/foo-300x225.jpg" srcset="https://example.com/foo-300x225.jpg 300w, https://example.com/foo-1024x768.jpg 1024w, https://example.com/foo-768x576.jpg 768w, https://example.com/foo-1536x1152.jpg 1536w, https://example.com/foo-2048x1536.jpg 2048w" sizes="auto, (max-width: 650px) 100vw, 650px" loading="eager">',
 				'expected' => '<img src="https://example.com/foo-300x225.jpg" srcset="https://example.com/foo-300x225.jpg 300w, https://example.com/foo-1024x768.jpg 1024w, https://example.com/foo-768x576.jpg 768w, https://example.com/foo-1536x1152.jpg 1536w, https://example.com/foo-2048x1536.jpg 2048w" sizes="(max-width: 650px) 100vw, 650px" loading="eager">',
 			),
+			'expected_when_auto_size_preceded_by_extra_commas' => array(
+				'input'    => '<img src="https://example.com/foo-300x225.jpg" srcset="https://example.com/foo-300x225.jpg 300w, https://example.com/foo-1024x768.jpg 1024w, https://example.com/foo-768x576.jpg 768w, https://example.com/foo-1536x1152.jpg 1536w, https://example.com/foo-2048x1536.jpg 2048w" sizes=",,,,,,,,,auto, (max-width: 650px) 100vw, 650px" loading="lazy">',
+				'expected' => '<img src="https://example.com/foo-300x225.jpg" srcset="https://example.com/foo-300x225.jpg 300w, https://example.com/foo-1024x768.jpg 1024w, https://example.com/foo-768x576.jpg 768w, https://example.com/foo-1536x1152.jpg 1536w, https://example.com/foo-2048x1536.jpg 2048w" sizes="auto, ,,,,,,,,,auto, (max-width: 650px) 100vw, 650px" loading="lazy">',
+			),
 		);
 	}