diff --git a/gnuviechadmin/osusers/tests/test_models.py b/gnuviechadmin/osusers/tests/test_models.py
index da78b92..c6dcf5e 100644
--- a/gnuviechadmin/osusers/tests/test_models.py
+++ b/gnuviechadmin/osusers/tests/test_models.py
@@ -11,12 +11,16 @@ from osusers.models import (
 )
 
 
-class AdditionalGroupTest(TestCase):
-    @override_settings(
-        CELERY_ALWAYS_EAGER=True,
-        CELERY_CACHE_BACKEND='memory',
-        BROKER_BACKEND='memory'
-    )
+@override_settings(
+    CELERY_ALWAYS_EAGER=True,
+    CELERY_CACHE_BACKEND='memory',
+    BROKER_BACKEND='memory'
+)
+class TestCaseWithCeleryTasks(TestCase):
+    pass
+
+
+class AdditionalGroupTest(TestCaseWithCeleryTasks):
     def test_clean_primary_group(self):
         group1 = Group.objects.create(groupname='test1', gid=1000)
         user = User.objects.create(
@@ -28,11 +32,6 @@ class AdditionalGroupTest(TestCase):
         self.assertEqual(
             cm.exception.message, CANNOT_USE_PRIMARY_GROUP_AS_ADDITIONAL)
 
-    @override_settings(
-        CELERY_ALWAYS_EAGER=True,
-        CELERY_CACHE_BACKEND='memory',
-        BROKER_BACKEND='memory'
-    )
     def test_clean_other_group(self):
         group1 = Group(groupname='test1', gid=1000)
         group2 = Group(groupname='test2', gid=1001)
@@ -42,13 +41,20 @@ class AdditionalGroupTest(TestCase):
         testsubj.clean()
 
 
-class GroupTest(TestCase):
+class GroupTest(TestCaseWithCeleryTasks):
     pass
 
 
-class ShadowTest(TestCase):
-    pass
+class ShadowTest(TestCaseWithCeleryTasks):
+    def test___str__(self):
+        group = Group.objects.create(
+            groupname='test', gid=1000)
+        user = User.objects.create(
+            username='test', uid=1000, group=group, homedir='/home/test',
+            shell='/bin/bash')
+        shadow = Shadow(user=user)
+        self.assertEqual(str(shadow), 'for user test (1000)')
 
 
-class UserTest(TestCase):
+class UserTest(TestCaseWithCeleryTasks):
     pass