notifications: Introduce Notification Middleware and NotificationEnvelope

To allow ourselves esier processing/modifying Notifications lets
introduce an idea of NotificationsEnvelope which represents a
Notification being sent and list of recipients.

The middleware approach will allow us to modify the Notification
behaviour by letting extensions to inject/modify the Notifications.

Each Middleware will retrieve a list of Envelopes MediaWiki wants to
send. Middlewares should iterate over envelopes and decide if those
want to add/remove/replace Notifications and/or Recipients.

Bug: T387996
Change-Id: Ib3ee35c75b2f4dcfdc516b9259a852dc73c4a778

1 files changed, 74 insertions, 0 deletions

diff --git a/tests/phpunit/integration/includes/Notification/MiddlewareChainTest.php b/tests/phpunit/integration/includes/Notification/MiddlewareChainTest.php
new file mode 100644
index 000000000000..4fda5639b16b
--- /dev/null
+++ b/tests/phpunit/integration/includes/Notification/MiddlewareChainTest.php
@@ -0,0 +1,74 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+namespace MediaWiki\Tests\Integration\Notification;
+
+use MediaWiki\MediaWikiServices;
+use MediaWiki\Notification\MiddlewareException;
+use MediaWiki\Notification\Notification;
+use MediaWiki\Notification\NotificationMiddlewareInterface;
+use MediaWiki\Notification\RecipientSet;
+use MediaWiki\Registration\ExtensionRegistry;
+use MediaWiki\User\UserIdentity;
+use MediaWikiIntegrationTestCase;
+use Wikimedia\ScopedCallback;
+
+/**
+ * @group Mail
+ * @covers \MediaWiki\Notification\MiddlewareChain
+ */
+class MiddlewareChainTest extends MediaWikiIntegrationTestCase {
+
+	/**
+	 * Test case when Middleware calls NotificationService::notify() to inject new notification
+	 * This can cause endless loops where Middleware triggers a notification, that triggers the
+	 * middleware again.
+	 *
+	 * @return void
+	 */
+	public function testMiddlewareCannotTriggerNotificationService() {
+		$this->expectException( MiddlewareException::class );
+
+		$scope = ExtensionRegistry::getInstance()->setAttributeForTest(
+			'NotificationMiddleware', [
+				[
+					"factory" => static function ()  {
+						return new class implements NotificationMiddlewareInterface {
+							public function handle( $batch, callable $next ): void {
+								MediaWikiServices::getInstance()
+									->getNotificationService()
+									->notify(
+										new Notification( "bad" ), new RecipientSet( [] )
+									);
+								$next();
+							}
+						};
+					},
+				],
+			]
+		);
+		$sut = MediaWikiServices::getInstance()->getNotificationService();
+		$user = $this->createMock( UserIdentity::class );
+		$sut->notify(
+			new Notification( "good" ), new RecipientSet( [ $user ] )
+		);
+		ScopedCallback::consume( $scope );
+	}
+}