HTML API: Ensure that get_modifiable_text() reads enqueued updates.

When `set_modifiable_text()` was added to the Tag Processor, it was considered that the same information could be queried after setting its value and before proceeding to the next token, but unfortunately overlooked that if the starting modifiable text length was zero, then the read in `get_modifiable_text()` would ignore enqueued updates.

In this patch, `get_modifiable_text()` will read any enqueued values before reading from the input HTML document to ensure consistency.

Follow-up to [58829].
Props dmsnell, jonsurrell, ramonopoly.
Fixes #61617.


git-svn-id: https://develop.svn.wordpress.org/trunk@58866 602fd350-edb4-49c9-b593-d223f7449a82

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

@@ -614,7 +614,7 @@ class WP_HTML_Tag_Processor {
 	 *
 	 * @since 6.5.0
 	 *
-	 * @var string
+	 * @var int
 	 */
 	private $text_length;
 
@@ -2894,11 +2894,13 @@ public function get_comment_type(): ?string {
 	 * @return string
 	 */
 	public function get_modifiable_text(): string {
-		if ( null === $this->text_starts_at || 0 === $this->text_length ) {
+		$has_enqueued_update = isset( $this->lexical_updates['modifiable text'] );
+
+		if ( ! $has_enqueued_update && ( null === $this->text_starts_at || 0 === $this->text_length ) ) {
 			return '';
 		}
 
-		$text = isset( $this->lexical_updates['modifiable text'] )
+		$text = $has_enqueued_update
 			? $this->lexical_updates['modifiable text']->text
 			: substr( $this->html, $this->text_starts_at, $this->text_length );
 

tests/phpunit/tests/html-api/wpHtmlTagProcessorModifiableText.php

@@ -39,6 +39,83 @@ public function test_get_modifiable_text_is_idempotent() {
 		}
 	}
 
+	/**
+	 * Ensures that `get_modifiable_text()` reads enqueued updates when read
+	 * from after writing; guarantees consistency through writes.
+	 *
+	 * @ticket 61617
+	 */
+	public function test_get_modifiable_text_is_consistent_after_writes() {
+		$before    = 'just some text';
+		$after     = 'different text';
+		$processor = new WP_HTML_Tag_Processor( $before );
+		$processor->next_token();
+
+		$this->assertSame(
+			'#text',
+			$processor->get_token_name(),
+			"Should have found text node but found '{$processor->get_token_name()}' instead: check test setup."
+		);
+
+		$this->assertSame(
+			$before,
+			$processor->get_modifiable_text(),
+			'Should have found initial test text: check test setup.'
+		);
+
+		$processor->set_modifiable_text( $after );
+		$this->assertSame(
+			$after,
+			$processor->get_modifiable_text(),
+			'Should have found enqueued updated text.'
+		);
+
+		$processor->get_updated_html();
+		$this->assertSame(
+			$after,
+			$processor->get_modifiable_text(),
+			'Should have found updated text.'
+		);
+	}
+
+	/**
+	 * Ensures that `get_modifiable_text()` reads enqueued updates when read from after
+	 * writing when starting from an empty text; guarantees consistency through writes.
+	 *
+	 * @ticket 61617
+	 */
+	public function test_get_modifiable_text_is_consistent_after_writes_to_empty_text() {
+		$after     = 'different text';
+		$processor = new WP_HTML_Tag_Processor( '<script></script>' );
+		$processor->next_token();
+
+		$this->assertSame(
+			'SCRIPT',
+			$processor->get_token_name(),
+			"Should have found text node but found '{$processor->get_token_name()}' instead: check test setup."
+		);
+
+		$this->assertSame(
+			'',
+			$processor->get_modifiable_text(),
+			'Should have found initial test text: check test setup.'
+		);
+
+		$processor->set_modifiable_text( $after );
+		$this->assertSame(
+			$after,
+			$processor->get_modifiable_text(),
+			'Should have found enqueued updated text.'
+		);
+
+		$processor->get_updated_html();
+		$this->assertSame(
+			$after,
+			$processor->get_modifiable_text(),
+			'Should have found updated text.'
+		);
+	}
+
 	/**
 	 * Ensures that updates to modifiable text that are shorter than the
 	 * original text do not cause the parser to lose its orientation.