test available set seeds

backend/tests/Feature/Database/DatabaseSeederTest.php

@@ -3,8 +3,10 @@
 namespace Tests\Feature\Database;
 
 use App\Auth\PasswordHasher;
+use App\Set\SetRepository;
 use App\Shared\ValueObject\EmailAddress;
 use App\User\UserRepository;
+use Database\Seeders\UserSeeder;
 use Illuminate\Foundation\Testing\RefreshDatabase;
 use Tests\TestCase;
 
@@ -36,4 +38,26 @@ class DatabaseSeederTest extends TestCase
             $user->getPasswordHash(),
         ));
     }
+
+    public function test_it_seeds_the_available_sets_idempotently(): void
+    {
+        $this->seed();
+        $this->seed();
+
+        $sets = app(SetRepository::class)->all();
+
+        $this->assertDatabaseCount('sets', 3);
+        $this->assertSame(
+            ['Bible', 'Course', 'Fitness Program'],
+            array_map(function ($set): string {
+                return $set->getName();
+            }, $sets),
+        );
+        foreach ($sets as $set) {
+            $this->assertSame(
+                UserSeeder::EMAIL,
+                $set->getCreator()->getEmail()->value(),
+            );
+        }
+    }
 }