Ticket #35580: 35580.2.diff

src/wp-includes/rest-api/class-wp-rest-server.php

@@ -228 +228 @@
                 $this->send_header( 'Content-Type', $content_type . '; charset=' . get_option( 'blog_charset' ) );
                 $this->send_header( 'X-Robots-Tag', 'noindex' );
 
+                $api_root = get_rest_url();
+                if ( ! empty( $api_root ) ) {
+                        $this->send_header( 'Link', '<' . esc_url_raw( $api_root ) . '>; rel="https://api.w.org/"' );
+                }
+
                 /*
                  * Mitigate possible JSONP Flash attacks.
                  *

tests/phpunit/tests/rest-api/rest-server.php

@@ -726 +726 @@
                 $this->assertEquals( 'noindex', $headers['X-Robots-Tag'] );
         }
 
+        public function test_link_header_on_requests() {
+                $api_root = get_rest_url();
+
+                $request = new WP_REST_Request( 'GET', '/', array() );
+
+                $result = $this->server->serve_request('/');
+                $headers = $this->server->sent_headers;
+
+                $this->assertEquals( '<' . esc_url_raw( $api_root ) . '>; rel="https://api.w.org/"', $headers['Link'] );
+        }
+
         public function test_nocache_headers_on_authenticated_requests() {
                 $editor = self::factory()->user->create( array( 'role' => 'editor' ) );
                 $request = new WP_REST_Request( 'GET', '/', array() );