diff --git a/user_app/apps.py b/user_app/apps.py
index f2d1d41..41a7627 100644
--- a/user_app/apps.py
+++ b/user_app/apps.py
@@ -1,6 +1,8 @@
 from django.apps import AppConfig
 
-
 class UserAppConfig(AppConfig):
     default_auto_field = 'django.db.models.BigAutoField'
     name = 'user_app'
+
+    def ready(self):
+        import user_app.signals
\ No newline at end of file
diff --git a/user_app/caching.py b/user_app/caching.py
index 1cefd41..d60cbc7 100644
--- a/user_app/caching.py
+++ b/user_app/caching.py
@@ -19,6 +19,7 @@ def get_cached_user(user_id):
     if user:
         user_data = serializers.serialize('json', [user])
         cache.set(cache_key, user_data, timeout=3600)
+
         return json.loads(user_data)[0]['fields']
     else:
         return None
diff --git a/user_app/models.py b/user_app/models.py
index 0686d48..526e250 100644
--- a/user_app/models.py
+++ b/user_app/models.py
@@ -1,9 +1,6 @@
+import uuid
 from django.contrib.auth.models import AbstractBaseUser, BaseUserManager, PermissionsMixin, Group, Permission
 from django.db import models
-from django.db.models.signals import post_save, post_delete
-from django.dispatch import receiver
-from django.core.cache import cache
-import uuid
 
 def generate_uuid_without_dashes():
     return uuid.uuid4().hex
@@ -53,12 +50,4 @@ class User(AbstractBaseUser, PermissionsMixin):
     REQUIRED_FIELDS = ['first_name']
 
     def __str__(self):
-        return self.email
-    
-# Cache invalidation
-@receiver(post_save, sender=User)
-@receiver(post_delete, sender=User)
-def clear_user_cache(sender, instance, **kwargs):
-    """Invalidate cache for the affected user"""
-    cache_key = f"user_{instance.id}"
-    cache.delete(cache_key)
\ No newline at end of file
+        return self.email
\ No newline at end of file
diff --git a/user_app/signals.py b/user_app/signals.py
new file mode 100644
index 0000000..e30492a
--- /dev/null
+++ b/user_app/signals.py
@@ -0,0 +1,11 @@
+from django.core.cache import cache
+from django.db.models.signals import post_save, post_delete
+from django.dispatch import receiver
+from .models import User
+
+@receiver(post_save, sender=User)
+@receiver(post_delete, sender=User)
+def clear_user_cache(sender, instance, **kwargs):
+    """Invalidate cache for the affected user"""
+    cache_key = f"user_{instance.id}"
+    cache.delete(cache_key)
\ No newline at end of file
diff --git a/user_app/tests.py b/user_app/tests.py
index 7ce503c..da443c3 100644
--- a/user_app/tests.py
+++ b/user_app/tests.py
@@ -1,3 +1,16 @@
 from django.test import TestCase
+from .models import User
+from .caching import get_cached_user
 
-# Create your tests here.
+class UserCacheTest(TestCase):
+    def test_cache_invalidierung_nach_speichern(self):
+        user = User.objects.create(first_name="Test", last_name="User", email="test@example.com")
+
+        cached_user = get_cached_user(user.id)
+        self.assertIsNotNone(cached_user)
+
+        user.first_name = "Updated"
+        user.save()
+
+        cached_user_after_update = get_cached_user(user.id)
+        self.assertIsNotNone(cached_user_after_update)
\ No newline at end of file