REST API: Add the site reading options to the index.

Exposes `page_for_posts`, `page_on_front` and `show_on_front` reading settings via REST API index.

Props mamaduka, audrasjb, spacedmonkey, timothyblynjacobs.
Fixes #63023.

git-svn-id: https://develop.svn.wordpress.org/trunk@59880 602fd350-edb4-49c9-b593-d223f7449a82

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

@@ -1371,6 +1371,9 @@ class WP_REST_Server {
 			'home'            => home_url(),
 			'gmt_offset'      => get_option( 'gmt_offset' ),
 			'timezone_string' => get_option( 'timezone_string' ),
+			'page_for_posts'  => (int) get_option( 'page_for_posts' ),
+			'page_on_front'   => (int) get_option( 'page_on_front' ),
+			'show_on_front'   => get_option( 'show_on_front' ),
 			'namespaces'      => array_keys( $this->namespaces ),
 			'authentication'  => array(),
 			'routes'          => $this->get_data_for_routes( $this->get_routes(), $request['context'] ),

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

@@ -1137,6 +1137,9 @@ class Tests_REST_Server extends WP_Test_REST_TestCase {
 		$this->assertArrayHasKey( 'home', $data );
 		$this->assertArrayHasKey( 'gmt_offset', $data );
 		$this->assertArrayHasKey( 'timezone_string', $data );
+		$this->assertArrayHasKey( 'page_for_posts', $data );
+		$this->assertArrayHasKey( 'page_on_front', $data );
+		$this->assertArrayHasKey( 'show_on_front', $data );
 		$this->assertArrayHasKey( 'namespaces', $data );
 		$this->assertArrayHasKey( 'authentication', $data );
 		$this->assertArrayHasKey( 'routes', $data );

tests/qunit/fixtures/wp-api-generated.js

@@ -12,6 +12,9 @@ mockedApiResponse.Schema = {
     "home": "http://example.org",
     "gmt_offset": "0",
     "timezone_string": "",
+    "page_for_posts": 0,
+    "page_on_front": 0,
+    "show_on_front": "posts",
     "namespaces": [
         "oembed/1.0",
         "wp/v2",