From 10bfe70f06396cb34cc559b3a516dcc56151124b Mon Sep 17 00:00:00 2001
From: Ryan McCue <rmccue@git.wordpress.org>
Date: Tue, 16 Feb 2016 05:50:21 +0000
Subject: [PATCH] REST API: Allow explicit HEAD callbacks.

HEAD callbacks can now be registered independently, with the GET
callback still used as a fallback.

Fixes #34841.


git-svn-id: https://develop.svn.wordpress.org/trunk@36535 602fd350-edb4-49c9-b593-d223f7449a82
---
 .../rest-api/class-wp-rest-server.php         |  6 ++++-
 tests/phpunit/tests/rest-api/rest-server.php  | 23 +++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/wp-includes/rest-api/class-wp-rest-server.php b/src/wp-includes/rest-api/class-wp-rest-server.php
index 5672cd39dd..cc9fda7014 100644
--- a/src/wp-includes/rest-api/class-wp-rest-server.php
+++ b/src/wp-includes/rest-api/class-wp-rest-server.php
@@ -820,7 +820,11 @@ class WP_REST_Server {
 				$callback  = $handler['callback'];
 				$response = null;
 
-				$checked_method = 'HEAD' === $method ? 'GET' : $method;
+				// Fallback to GET method if no HEAD method is registered.
+				$checked_method = $method;
+				if ( 'HEAD' === $method && empty( $handler['methods']['HEAD'] ) ) {
+					$checked_method = 'GET';
+				}
 				if ( empty( $handler['methods'][ $checked_method ] ) ) {
 					continue;
 				}
diff --git a/tests/phpunit/tests/rest-api/rest-server.php b/tests/phpunit/tests/rest-api/rest-server.php
index 768374d754..52b3ba6ca3 100644
--- a/tests/phpunit/tests/rest-api/rest-server.php
+++ b/tests/phpunit/tests/rest-api/rest-server.php
@@ -138,6 +138,29 @@ class Tests_REST_Server extends WP_Test_REST_TestCase {
 		$this->assertEquals( 200, $response->get_status() );
 	}
 
+	/**
+	 * Plugins should be able to register explicit HEAD callbacks before the
+	 * GET callback.
+	 *
+	 * @depends test_head_request_handled_by_get
+	 */
+	public function test_explicit_head_callback() {
+		register_rest_route( 'head-request', '/test', array(
+			array(
+				'methods' => array( 'HEAD' ),
+				'callback' => '__return_true',
+			),
+			array(
+				'methods' => array( 'GET' ),
+				'callback' => '__return_false',
+				'permission_callback' => array( $this, 'permission_denied' ),
+			),
+		));
+		$request = new WP_REST_Request( 'HEAD', '/head-request/test' );
+		$response = $this->server->dispatch( $request );
+		$this->assertEquals( 200, $response->get_status() );
+	}
+
 	/**
 	 * Pass a capability which the user does not have, this should
 	 * result in a 403 error.