Ticket #34292: 34292.diff

src/wp-includes/default-filters.php

@@ -233 +233 @@
 add_action( 'wp_head',             'wp_print_head_scripts',            9    );
 add_action( 'wp_head',             'wp_generator'                           );
 add_action( 'wp_head',             'rel_canonical'                          );
+add_action( 'wp_head',             'wp_dns_prefetch'                        );
 add_action( 'wp_head',             'wp_shortlink_wp_head',            10, 0 );
 add_action( 'wp_head',             'wp_site_icon',                    99    );
 add_action( 'wp_footer',           'wp_print_footer_scripts',         20    );

src/wp-includes/general-template.php

@@ -2523 +2523 @@
 }
 
 /**
+ * Prints out domains to prefetch for page speed optimization.
+ *
+ * @since 4.4.0
+ */
+function wp_dns_prefetch() {
+        /**
+         * Filter the domains to prefetch for page speed optimization.
+         *
+         * @since 4.4.0
+         *
+         * @param array $prefetch_urls Domains to prefetch.
+         */
+        $prefetch_domains = apply_filters( 'dns_prefetch_domains', array() );
+        $prefetch_domains = array_unique( array_map( 'strtolower', $prefetch_domains ) );
+
+        foreach ( $prefetch_domains as $domain ) {
+                $domain = esc_url( untrailingslashit( $domain ), array('http', 'https') );
+                printf( "<link rel='dns-prefetch' href='%s'>\r\n", $domain );
+        }
+}
+
+/**
  * Whether the user should have a WYSIWIG editor.
  *
  * Checks that the user requires a WYSIWIG editor and that the editor is

tests/phpunit/tests/general/template.php

@@ -177 +177 @@
                 $this->site_icon_id  = wp_insert_attachment( $attachment, $upload['file'] );
                 wp_update_attachment_metadata( $this->site_icon_id, wp_generate_attachment_metadata( $this->site_icon_id, $upload['file'] ) );
         }
+
+        /**
+         * @ticket 34292
+         */
+        function test_wp_dns_prefetch() {
+                $this->assertEmpty( get_echo( 'wp_dns_prefetch' ) );
+
+                add_filter( 'dns_prefetch_domains', array( $this, '_add_dns_prefetch_domains' ) );
+
+                $expected = "<link rel='dns-prefetch' href='http://wordpress.org'>\r\n" .
+                            "<link rel='dns-prefetch' href='https://google.com'>\r\n" .
+                            "<link rel='dns-prefetch' href='//make.wordpress.org'>\r\n";
+
+                $this->assertEquals( $expected, get_echo( 'wp_dns_prefetch' ) );
+        }
+
+        function _add_dns_prefetch_domains( $domains ) {
+                $domains[] = 'http://wordpress.org';
+                $domains[] = 'https://google.com';
+                $domains[] = '//make.wordpress.org';
+
+                return $domains;
+        }
 }