refactor: move attendees into the fake repository

tests/FakeEventRepository.php

@@ -5,10 +5,15 @@ declare(strict_types=1);
 namespace App\Tests;
 
 use App\EventRepository;
+use Tightenco\Collect\Support\Collection;
 
 final class FakeEventRepository implements EventRepository
 {
-    public function getConfirmedAttendees(): array {
-        return [];
+    public function getConfirmedAttendees(): Collection {
+        return Collection::make([
+            ['name' => 'matthew s.'],
+            ['name' => 'Michael P.'],
+            ['name' => 'Kathryn "Kat" R.'],
+        ]);
     }
 }