Twenty Twenty-One: Respect custom text of the more tag in the continue reading link

src/wp-content/themes/twentytwentyone/inc/template-functions.php

@@ -163,19 +163,39 @@ function twenty_twenty_one_continue_reading_link_excerpt() {
 // Filter the excerpt more link.
 add_filter( 'excerpt_more', 'twenty_twenty_one_continue_reading_link_excerpt' );
 
+/**
+ * Checks whether the current post sets its own text for the more link.
+ *
+ * @return bool True if the post content has a `<!--more Custom text-->` tag.
+ */
+function twenty_twenty_one_has_custom_more_text() {
+	return 1 === preg_match( '/<!--more(.+?)-->/', (string) get_post_field( 'post_content', get_the_ID() ), $matches ) && '' !== trim( $matches[1] );
+}
+
 /**
  * Creates the continue reading link.
  *
  * @since Twenty Twenty-One 1.0
+ *
+ * @param string $more_link_element Read More link element.
+ * @param string $more_link_text    Read More text.
+ * @return string|void The link markup, or nothing in the admin.
  */
-function twenty_twenty_one_continue_reading_link() {
-	if ( ! is_admin() ) {
-		return '<div class="more-link-container"><a class="more-link" href="' . esc_url( get_permalink() ) . '#more-' . esc_attr( get_the_ID() ) . '">' . twenty_twenty_one_continue_reading_text() . '</a></div>';
+function twenty_twenty_one_continue_reading_link( $more_link_element = '', $more_link_text = '' ) {
+	if ( is_admin() ) {
+		return;
 	}
+
+	$link_text = twenty_twenty_one_continue_reading_text();
+	if ( twenty_twenty_one_has_custom_more_text() ) {
+		$link_text = esc_html( $more_link_text ) . the_title( ' <span class="screen-reader-text">', '</span>', false );
+	}
+
+	return '<div class="more-link-container"><a class="more-link" href="' . esc_url( get_permalink() ) . '#more-' . esc_attr( get_the_ID() ) . '">' . $link_text . '</a></div>';
 }
 
 // Filter the content more link.
-add_filter( 'the_content_more_link', 'twenty_twenty_one_continue_reading_link' );
+add_filter( 'the_content_more_link', 'twenty_twenty_one_continue_reading_link', 10, 2 );
 
 if ( ! function_exists( 'twenty_twenty_one_post_title' ) ) {
 	/**

tests/phpunit/tests/theme/twentyTwentyOneContinueReadingLink.php

@@ -0,0 +1,110 @@
+<?php
+
+/**
+ * @group themes
+ *
+ * @covers ::twenty_twenty_one_continue_reading_link
+ */
+class Tests_Theme_TwentyTwentyOneContinueReadingLink extends WP_UnitTestCase {
+
+	/**
+	 * The names of the globals these tests overwrite.
+	 *
+	 * @var string[]
+	 */
+	private array $global_names = array( 'post', 'more' );
+
+	/**
+	 * The values of those globals before the current test ran, keyed by name.
+	 *
+	 * A name is absent when the global was not set.
+	 *
+	 * @var array<string, mixed>
+	 */
+	private array $original_globals = array();
+
+	public function set_up() {
+		parent::set_up();
+
+		// `backupGlobals` is disabled for the suite, so these have to be restored by hand.
+		foreach ( $this->global_names as $global_name ) {
+			if ( array_key_exists( $global_name, $GLOBALS ) ) {
+				$this->original_globals[ $global_name ] = $GLOBALS[ $global_name ];
+			}
+		}
+
+		$template_functions = WP_CONTENT_DIR . '/themes/twentytwentyone/inc/template-functions.php';
+		if ( ! file_exists( $template_functions ) ) {
+			$this->markTestSkipped( 'The Twenty Twenty-One theme is not installed.' );
+		}
+		require_once $template_functions;
+	}
+
+	public function tear_down() {
+		foreach ( $this->global_names as $global_name ) {
+			if ( array_key_exists( $global_name, $this->original_globals ) ) {
+				$GLOBALS[ $global_name ] = $this->original_globals[ $global_name ];
+			} else {
+				unset( $GLOBALS[ $global_name ] );
+			}
+		}
+
+		parent::tear_down();
+	}
+
+	private function set_up_post( string $content ): void {
+		$post_id = self::factory()->post->create( array( 'post_content' => $content ) );
+
+		$GLOBALS['post'] = get_post( $post_id );
+		setup_postdata( $GLOBALS['post'] );
+	}
+
+	/**
+	 * @ticket 52683
+	 */
+	public function test_uses_custom_more_text_when_set() {
+		$this->set_up_post( 'Teaser<!--more Read the full story-->Rest' );
+
+		$link = twenty_twenty_one_continue_reading_link( '', 'Read the full story' );
+
+		$this->assertStringContainsString( '>Read the full story <span class="screen-reader-text">', $link );
+		$this->assertStringNotContainsString( 'Continue reading', $link );
+	}
+
+	/**
+	 * @ticket 52683
+	 */
+	public function test_uses_theme_text_without_custom_more_text() {
+		$this->set_up_post( 'Teaser<!--more-->Rest' );
+
+		$link = twenty_twenty_one_continue_reading_link( '', twenty_twenty_one_continue_reading_text() );
+
+		$this->assertStringContainsString( 'Continue reading', $link );
+		$this->assertStringContainsString( 'class="more-link"', $link );
+	}
+
+	/**
+	 * @ticket 52683
+	 */
+	public function test_escapes_custom_more_text() {
+		$this->set_up_post( 'Teaser<!--more Tom & Jerry-->Rest' );
+
+		$link = twenty_twenty_one_continue_reading_link( '', 'Tom & Jerry' );
+
+		$this->assertStringContainsString( 'Tom &amp; Jerry', $link );
+	}
+
+	/**
+	 * @ticket 52683
+	 */
+	public function test_the_content_shows_custom_more_text() {
+		add_filter( 'the_content_more_link', 'twenty_twenty_one_continue_reading_link', 10, 2 );
+		$GLOBALS['more'] = 0;
+		$this->set_up_post( 'Teaser<!--more Read the full story-->Rest' );
+
+		$content = get_the_content( twenty_twenty_one_continue_reading_text() );
+
+		$this->assertStringContainsString( 'Read the full story', $content );
+		$this->assertStringContainsString( 'more-link-container', $content );
+	}
+}