update fake token generator to take a preset number of tokens

backend/tests/Fakes/FakeTokenGenerator.php

@@ -3,11 +3,27 @@
 namespace Tests\Fakes;
 
 use App\Auth\TokenGenerator;
+use RuntimeException;
 
 class FakeTokenGenerator implements TokenGenerator
 {
+    private int $callCount = 0;
+
+    /**
+     * @param  string[]  $tokens
+     */
+    public function __construct(private array $tokens) {}
+
     public function generate(): string
     {
-        return 'fake-token-123';
+        if ($this->callCount >= count($this->tokens)) {
+            throw new RuntimeException(
+                'FakeTokenGenerator exhausted'
+            );
+        }
+        $token = $this->tokens[$this->callCount];
+        $this->callCount++;
+
+        return $token;
     }
 }

backend/tests/Unit/Auth/UseCases/CreateSessionTest.php

@@ -22,7 +22,7 @@ class CreateSessionTest extends TestCase
     protected function setUp(): void
     {
         $this->sessionRepo = new FakeSessionRepository();
-        $this->tokenGenerator = new FakeTokenGenerator();
+        $this->tokenGenerator = new FakeTokenGenerator(['fake-token-123']);
         $this->clock = new FakeClock(
             new DateTimeImmutable('2026-05-18 12:00:00')
         );