feat(rest): add DELETE /notifications/{id}

includes/persistence/class-wpdb-notification-repository.php

@@ -62,4 +62,30 @@ public function add( Notifications\Notification $notification ) {
 		// TODO: Implement query.
 		return -1;
 	}
+
+	/**
+	 * Remove a user's notification.
+	 *
+	 * Only the user's queue row is removed, the message itself can still
+	 * belong to other users.
+	 *
+	 * @param int $message_id Message ID.
+	 * @param int $user_id    User who owns the notification.
+	 *
+	 * @return bool Whether a notification was removed.
+	 */
+	public function remove( int $message_id, int $user_id ): bool {
+		global $wpdb;
+
+		$deleted = $wpdb->delete(
+			$wpdb->prefix . 'notifications_queue',
+			array(
+				'message_id' => $message_id,
+				'user_id'    => $user_id,
+			),
+			array( '%d', '%d' )
+		);
+
+		return ! empty( $deleted );
+	}
 }

includes/persistence/interface-notification-repository.php

@@ -70,4 +70,14 @@ public function find_latest(
 	 * @return int ID that the notification was stored under.
 	 */
 	public function add( Notifications\Notification $notification );
+
+	/**
+	 * Remove a user's notification.
+	 *
+	 * @param int $message_id Message ID.
+	 * @param int $user_id    User who owns the notification.
+	 *
+	 * @return bool Whether a notification was removed.
+	 */
+	public function remove( int $message_id, int $user_id ): bool;
 }

includes/restapi/class-notification-controller.php

@@ -12,6 +12,8 @@
 use WP_REST_Request;
 use WP_REST_Response;
 use WP_REST_Server;
+use WP\Notifications\Persistence\Notification_Repository;
+use WP\Notifications\Persistence\Wpdb_Notification_Repository;
 
 /**
  * REST API Notification Controller class
@@ -32,6 +34,23 @@ class Notification_Controller extends WP_REST_Controller {
 	 */
 	public const NOTIFICATION_BASE = 'notifications';
 
+	/**
+	 * Notification repository.
+	 *
+	 * @var Notification_Repository
+	 */
+	protected $repository;
+
+	/**
+	 * Constructor.
+	 *
+	 * @param Notification_Repository|null $repository Optional. Notification repository,
+	 *                                                 defaults to the wpdb repository.
+	 */
+	public function __construct( ?Notification_Repository $repository = null ) {
+		$this->repository = $repository ?? new Wpdb_Notification_Repository();
+	}
+
 	/**
 	 * Register REST routes
 	 *
@@ -52,6 +71,26 @@ public function register_routes(): void {
 			),
 			false
 		);
+
+		register_rest_route(
+			self::NAMESPACE,
+			self::NOTIFICATION_BASE . '/(?P<id>[\d]+)',
+			array(
+				'args'   => array(
+					'id' => array(
+						'description' => __( 'Unique identifier for the notification.' ),
+						'type'        => 'integer',
+					),
+				),
+				array(
+					'methods'             => WP_REST_Server::DELETABLE,
+					'callback'            => array( $this, 'delete_item' ),
+					'permission_callback' => array( $this, 'delete_item_permissions_check' ),
+				),
+				'schema' => array( $this, 'get_public_item_schema' ),
+			),
+			false
+		);
 	}
 
 	/**
@@ -83,6 +122,53 @@ public function get_items( $request ) {
 		return rest_ensure_response( array() );
 	}
 
+	/**
+	 * Checks if a given request has access to delete a notification.
+	 *
+	 * @param WP_REST_Request $request Full details about the request.
+	 *
+	 * @return true|WP_Error True if the request has access to delete the item, error object otherwise.
+	 */
+	public function delete_item_permissions_check( $request ) {
+		if ( ! is_user_logged_in() ) {
+			return new WP_Error(
+				'rest_notifications_login_required',
+				__( 'Sorry, you must be logged in to delete notifications.' ),
+				array( 'status' => 401 )
+			);
+		}
+		return true;
+	}
+
+	/**
+	 * Delete a notification of the current user.
+	 *
+	 * The ID is a message ID. Only the current user's copy is removed, so a
+	 * notification of another user returns the same error as a missing one.
+	 *
+	 * @param WP_REST_Request $request Received REST request
+	 *
+	 * @return WP_REST_RESPONSE|WP_Error REST response or WP Error
+	 */
+	public function delete_item( $request ) {
+		$id = (int) $request['id'];
+
+		if ( ! $this->repository->remove( $id, get_current_user_id() ) ) {
+			return new WP_Error(
+				'rest_notification_invalid_id',
+				__( 'Invalid notification ID.' ),
+				array( 'status' => 404 )
+			);
+		}
+
+		return rest_ensure_response(
+			array(
+				'deleted' => true,
+				'id'      => $id,
+			)
+		);
+	}
+
 	/**
 	 * Retrieves the notification's schema, conforming to JSON Schema.
 	 *

tests/phpunit/tests/rest-api/test-notification-controller.php

@@ -3,6 +3,48 @@
  * Unit tests covering WP/Notifications/Notification_Controller functionality.
  */
 class WP_Test_REST_Notification_Controller extends WP_Test_REST_Controller_Testcase {
+	protected static $user_id;
+	protected static $other_user_id;
+
+	public static function wpSetUpBeforeClass( WP_UnitTest_Factory $factory ) {
+		require_once WP_FEATURE_NOTIFICATION_PLUGIN_DIR . '/includes/class-activator.php';
+
+		// Created outside the test transaction so the table is not temporary.
+		WP\Notifications\Activator::create_tables_v1();
+
+		self::$user_id       = $factory->user->create();
+		self::$other_user_id = $factory->user->create();
+	}
+
+	public static function wpTearDownAfterClass() {
+		self::delete_user( self::$user_id );
+		self::delete_user( self::$other_user_id );
+	}
+
+	protected function add_queue_row( int $message_id, int $user_id ) {
+		global $wpdb;
+
+		$wpdb->insert(
+			$wpdb->prefix . 'notifications_queue',
+			array(
+				'message_id' => $message_id,
+				'user_id'    => $user_id,
+			),
+			array( '%d', '%d' )
+		);
+	}
+
+	protected function count_queue_rows( int $message_id ): int {
+		global $wpdb;
+
+		return (int) $wpdb->get_var(
+			$wpdb->prepare(
+				"SELECT COUNT(*) FROM {$wpdb->prefix}notifications_queue WHERE message_id = %d",
+				$message_id
+			)
+		);
+	}
+
 	public function test_register_routes() {
 		$this->markTestSkipped( 'TODO Implement' );
 	}
@@ -28,7 +70,54 @@ public function test_update_item() {
 	}
 
 	public function test_delete_item() {
-		$this->markTestSkipped( 'TODO Implement' );
+		$this->add_queue_row( 42, self::$user_id );
+		$this->add_queue_row( 42, self::$other_user_id );
+		wp_set_current_user( self::$user_id );
+
+		$request  = new WP_REST_Request( 'DELETE', '/wp-notifications/v1/notifications/42' );
+		$response = rest_get_server()->dispatch( $request );
+
+		$this->assertSame( 200, $response->get_status() );
+		$this->assertSame(
+			array(
+				'deleted' => true,
+				'id'      => 42,
+			),
+			$response->get_data()
+		);
+		// The other user's copy of the message must stay.
+		$this->assertSame( 1, $this->count_queue_rows( 42 ) );
+	}
+
+	public function test_delete_item_logged_out() {
+		$this->add_queue_row( 43, self::$user_id );
+		wp_set_current_user( 0 );
+
+		$request  = new WP_REST_Request( 'DELETE', '/wp-notifications/v1/notifications/43' );
+		$response = rest_get_server()->dispatch( $request );
+
+		$this->assertErrorResponse( 'rest_notifications_login_required', $response, 401 );
+		$this->assertSame( 1, $this->count_queue_rows( 43 ) );
+	}
+
+	public function test_delete_item_of_other_user() {
+		$this->add_queue_row( 44, self::$other_user_id );
+		wp_set_current_user( self::$user_id );
+
+		$request  = new WP_REST_Request( 'DELETE', '/wp-notifications/v1/notifications/44' );
+		$response = rest_get_server()->dispatch( $request );
+
+		$this->assertErrorResponse( 'rest_notification_invalid_id', $response, 404 );
+		$this->assertSame( 1, $this->count_queue_rows( 44 ) );
+	}
+
+	public function test_delete_item_invalid_id() {
+		wp_set_current_user( self::$user_id );
+
+		$request  = new WP_REST_Request( 'DELETE', '/wp-notifications/v1/notifications/999999' );
+		$response = rest_get_server()->dispatch( $request );
+
+		$this->assertErrorResponse( 'rest_notification_invalid_id', $response, 404 );
 	}
 
 	public function test_prepare_item() {