HTML API: Preserve XMP raw text serialization

Author: sirreal

src/wp-includes/html-api/class-wp-html-processor.php

@@ -1498,6 +1498,7 @@ public function serialize_token(): string {
 
 				case 'SCRIPT':
 				case 'STYLE':
+				case 'XMP':
 					break;
 
 				default:

tests/phpunit/tests/html-api/wpHtmlProcessor-serialize.php

@@ -134,6 +134,26 @@ public function test_style_contents_are_not_escaped() {
 		);
 	}
 
+	/**
+	 * Ensures that XMP contents are not escaped, as they are not parsed like text nodes are.
+	 *
+	 * @ticket 65372
+	 */
+	public function test_xmp_contents_are_not_escaped() {
+		$normalized = WP_HTML_Processor::normalize( "<xmp>apples > or\x00anges & carrots</xmp>" );
+
+		$this->assertSame(
+			"<xmp>apples > or\u{FFFD}anges & carrots</xmp>",
+			$normalized,
+			'Should have preserved text inside an XMP element, except for replacing NULL bytes.'
+		);
+		$this->assertSame(
+			$normalized,
+			WP_HTML_Processor::normalize( $normalized ),
+			'Normalizing already-normalized XMP should not escape the raw text again.'
+		);
+	}
+
 	public function test_unexpected_closing_tags_are_removed() {
 		$this->assertSame(
 			WP_HTML_Processor::normalize( 'one</div>two</span>three' ),