Add event extender (used for domain events) (#2097)

tests/integration/extenders/EventTest.php

@@ -0,0 +1,84 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\Tests\integration\extenders;
+
+use Flarum\Extend;
+use Flarum\Group\Event\Created;
+use Flarum\Group\Group;
+use Flarum\Tests\integration\TestCase;
+use Illuminate\Contracts\Events\Dispatcher;
+use Illuminate\Contracts\Translation\Translator;
+
+class EventTest extends TestCase
+{
+    protected function buildGroup()
+    {
+        $events = $this->app()->getContainer()->make(Dispatcher::class);
+
+        $group = Group::build('test group', 'test groups', '#000000', 'fas fa-crown');
+        $group->save();
+
+        $events->dispatch(new Created($group));
+
+        return $group;
+    }
+
+    /**
+     * @test
+     */
+    public function custom_listener_doesnt_work_by_default()
+    {
+        $group = $this->buildGroup();
+
+        $this->assertEquals($group->name_singular, 'test group');
+    }
+
+    /**
+     * @test
+     */
+    public function custom_listener_works_with_closure()
+    {
+        $this->extend((new Extend\Event)->listen(Created::class, function (Created $event) {
+            $event->group->name_singular = 'modified group';
+        }));
+
+        $group = $this->buildGroup();
+
+        $this->assertEquals($group->name_singular, 'modified group');
+    }
+
+    /**
+     * @test
+     */
+    public function custom_listener_works_with_class_with_handle_method_and_can_inject_stuff()
+    {
+        // Because it injects a translator, this also tests that stuff can be injected into this callback.
+        $this->extend((new Extend\Event)->listen(Created::class, CustomListener::class));
+
+        $group = $this->buildGroup();
+
+        $this->assertEquals($group->name_singular, 'core.group.admin');
+    }
+}
+
+class CustomListener
+{
+    protected $translator;
+
+    public function __construct(Translator $translator)
+    {
+        $this->translator = $translator;
+    }
+
+    public function handle(Created $event)
+    {
+        $event->group->name_singular = $this->translator->trans('core.group.admin');
+    }
+}