Backport WordPress/gutenberg#52758

Updated typo in wp_add_fields_to_navigation_fallback_embeded_links
Added tests (failing)

src/wp-includes/navigation-fallback.php

@@ -22,20 +22,35 @@
  * @param array $schema the schema for the `wp_navigation` post.
  * @return array the modified schema.
  */
-function wp_add_fields_to_navigation_fallback_embeded_links( $schema ) {
+function wp_add_fields_to_navigation_fallback_embedded_links( $schema ) {
 	// Expose top level fields.
 	$schema['properties']['status']['context']  = array_merge( $schema['properties']['status']['context'], array( 'embed' ) );
 	$schema['properties']['content']['context'] = array_merge( $schema['properties']['content']['context'], array( 'embed' ) );
 
-	// Expose sub properties of content field.
+	/*
+	 * Exposes sub properties of content field.
+	 * These sub properties aren't exposed by the posts controller by default,
+	 * only when the post type attribute is `'editor'`.
+	 *
+	 * @see WP_REST_Posts_Controller::get_item_schema()
+	 */
 	$schema['properties']['content']['properties']['raw']['context']           = array_merge( $schema['properties']['content']['properties']['raw']['context'], array( 'embed' ) );
 	$schema['properties']['content']['properties']['rendered']['context']      = array_merge( $schema['properties']['content']['properties']['rendered']['context'], array( 'embed' ) );
 	$schema['properties']['content']['properties']['block_version']['context'] = array_merge( $schema['properties']['content']['properties']['block_version']['context'], array( 'embed' ) );
 
+	/*
+	 * Exposes sub properties of title field.
+	 * These sub properties aren't exposed by the posts controller by default,
+	 * only when the post type attribute is `'editor'`.
+	 *
+	 * @see WP_REST_Posts_Controller::get_item_schema()
+	 */
+	$schema['properties']['title']['properties']['raw']['context'] = array_merge( $schema['properties']['title']['properties']['raw']['context'], array( 'embed' ) );
+
 	return $schema;
 }
 
 add_filter(
 	'rest_wp_navigation_item_schema',
-	'wp_add_fields_to_navigation_fallback_embeded_links'
+	'wp_add_fields_to_navigation_fallback_embedded_links'
 );

tests/phpunit/tests/rest-api/rest-navigation-fallback-controller.php

@@ -143,6 +143,49 @@ public function test_adds_links() {
 		$this->assertTrue( $links['self'][0]['attributes']['embeddable'], 'Self link should be embeddable.' );
 	}
 
+	/**
+	 * Tests that the correct filters are applied to the context parameter.
+	 *
+	 * By default, the REST response for the Posts Controller will not return all fields
+	 * when the context is set to 'embed'. Assert that correct additional fields are added
+	 * to the embedded Navigation Post, when the navigation fallback endpoint
+	 * is called with the `_embed` param.
+	 *
+	 * @ticket 58557
+	 * @covers wp_add_fields_to_navigation_fallback_embeded_links
+	 *
+	 * @since 6.3.0 Added Navigation Fallbacks endpoint.
+	 */
+	public function test_embedded_navigation_post_contains_required_fields() {
+		// First we'll use the navigation fallback to get a link to the navigation endpoint.
+		$request  = new WP_REST_Request( 'GET', '/wp-block-editor/v1/navigation-fallback' );
+		$response = rest_get_server()->dispatch( $request );
+		$links    = $response->get_links();
+
+		// Extract the navigation endpoint URL from the response.
+		$embedded_navigation_href = $links['self'][0]['href'];
+		preg_match( '/\?rest_route=(.*)/', $embedded_navigation_href, $matches );
+		$navigation_endpoint = $matches[1];
+
+		// Fetch the "linked" navigation post from the endpoint, with the context parameter set to 'embed' to simulate fetching embedded links.
+		$request = new WP_REST_Request( 'GET', $navigation_endpoint );
+		$request->set_param( 'context', 'embed' );
+		$response = rest_get_server()->dispatch( $request );
+		$data     = $response->get_data();
+
+		// Verify that the additional status field is present.
+		$this->assertArrayHasKey( 'status', $data, 'Response title should contain a "status" field.' );
+
+		// Verify that the additional content fields are present.
+		$this->assertArrayHasKey( 'content', $data, 'Response should contain a "content" field.' );
+		$this->assertArrayHasKey( 'raw', $data['content'], 'Response content should contain a "raw" field.' );
+		$this->assertArrayHasKey( 'rendered', $data['content'], 'Response content should contain a "rendered" field.' );
+		$this->assertArrayHasKey( 'block_version', $data['content'], 'Response should contain a "block_version" field.' );
+
+		// Verify that the additional title.raw field is present.
+		$this->assertArrayHasKey( 'raw', $data['title'], 'Response title should contain a "raw" key.' );
+	}
+
 	private function get_navigations_in_database() {
 		$navs_in_db = new WP_Query(
 			array(