Outbox: Properly handle username requests (#1559)

* Add failing test

* Add changelog

* Make tests pass

Author: obenland

.github/changelog/1559-from-description

@@ -0,0 +1,4 @@
+Significance: patch
+Type: fixed
+
+Outbox endpoint bug where non-numeric usernames caused errors when querying Outbox data.

includes/rest/class-outbox-controller.php

@@ -99,9 +99,9 @@ public function validate_user_id( $user_id ) {
 	 * @return \WP_REST_Response|\WP_Error Response object on success, or WP_Error object on failure.
 	 */
 	public function get_items( $request ) {
-		$user_id = $request->get_param( 'user_id' );
 		$page    = $request->get_param( 'page' ) ?? 1;
-		$user    = Actors::get_by_various( $user_id );
+		$user    = Actors::get_by_various( $request->get_param( 'user_id' ) );
+		$user_id = $user->get__id();
 
 		/**
 		 * Action triggered prior to the ActivityPub profile being created and sent to the client.

tests/includes/rest/class-test-outbox-controller.php

@@ -111,6 +111,19 @@ public function test_get_items() {
 		$this->assertEquals( 200, $response->get_status() );
 	}
 
+	/**
+	 * Test getting items by passing the username instead of the user ID.
+	 *
+	 * @covers ::get_items
+	 */
+	public function test_get_items_with_username() {
+		$request  = new \WP_REST_Request( 'GET', sprintf( '/%s/actors/%s/outbox', ACTIVITYPUB_REST_NAMESPACE, get_userdata( self::$user_id )->user_nicename ) );
+		$response = \rest_get_server()->dispatch( $request );
+		$data     = $response->get_data();
+
+		$this->assertEquals( 10, $data['totalItems'] );
+	}
+
 	/**
 	 * Test schema.
 	 *