diff --git a/jdav_web/contrib/tests.py b/jdav_web/contrib/tests.py
index 99493e1..45adca4 100644
--- a/jdav_web/contrib/tests.py
+++ b/jdav_web/contrib/tests.py
@@ -1,13 +1,18 @@
-from django.test import TestCase
+from datetime import datetime, timedelta
+from decimal import Decimal
+from django.test import TestCase, RequestFactory
 from django.contrib.auth import get_user_model
 from django.contrib import admin
 from django.db import models
-from django.test import RequestFactory
-from unittest.mock import Mock
+from django.core.exceptions import ValidationError
+from django.core.files.uploadedfile import SimpleUploadedFile
+from django.utils.translation import gettext_lazy as _
+from unittest.mock import Mock, patch
 from rules.contrib.models import RulesModelMixin, RulesModelBase
 from contrib.models import CommonModel
 from contrib.rules import has_global_perm
 from contrib.admin import CommonAdminMixin
+from utils import file_size_validator, RestrictedFileField, cvt_to_decimal, get_member, normalize_name, normalize_filename, coming_midnight, mondays_until_nth
 
 User = get_user_model()
 
@@ -91,3 +96,80 @@ class CommonAdminMixinTestCase(TestCase):
 
         # Verify that the formfield_overrides were used
         self.assertIsNotNone(result)
+
+
+class UtilsTestCase(TestCase):
+    def setUp(self):
+        self.user = User.objects.create_user(
+            username='testuser',
+            email='test@example.com',
+            password='testpass123'
+        )
+
+    def test_file_size_validator_exceeds_limit(self):
+        """Test file_size_validator when file exceeds size limit"""
+        validator = file_size_validator(1)  # 1MB limit
+
+        # Create a mock file that exceeds the limit (2MB)
+        mock_file = Mock()
+        mock_file.size = 2 * 1024 * 1024  # 2MB
+
+        with self.assertRaises(ValidationError) as cm:
+            validator(mock_file)
+
+        # Check for the translated error message
+        expected_message = str(_('Please keep filesize under {} MiB. Current filesize: {:10.2f} MiB.').format(1, 2.00))
+        self.assertIn(expected_message, str(cm.exception))
+
+    def test_restricted_file_field_content_type_not_supported(self):
+        """Test RestrictedFileField when content type is not supported"""
+        field = RestrictedFileField(content_types=['image/jpeg'])
+
+        # Create mock data with unsupported content type
+        mock_data = Mock()
+        mock_data.file = Mock()
+        mock_data.file.content_type = "text/plain"
+
+        # Mock the super().clean() to return our mock data
+        with patch.object(models.FileField, 'clean', return_value=mock_data):
+            with self.assertRaises(ValidationError) as cm:
+                field.clean("dummy")
+
+            # Check for the translated error message
+            expected_message = str(_('Filetype not supported.'))
+            self.assertIn(expected_message, str(cm.exception))
+
+    def test_restricted_file_field_size_exceeds_limit(self):
+        """Test RestrictedFileField when file size exceeds limit"""
+        field = RestrictedFileField(max_upload_size=1)  # 1 byte limit
+
+        # Create mock data with file that exceeds size limit
+        mock_data = Mock()
+        mock_data.file = Mock()
+        mock_data.file.content_type = "text/plain"
+        mock_data.file._size = 2  # 2 bytes, exceeds limit
+
+        # Mock the super().clean() to return our mock data
+        with patch.object(models.FileField, 'clean', return_value=mock_data):
+            with self.assertRaises(ValidationError) as cm:
+                field.clean("dummy")
+
+            # Check for the translated error message
+            expected_message = str(_('Please keep filesize under {}. Current filesize: {}').format(1, 2))
+            self.assertIn(expected_message, str(cm.exception))
+
+    def test_mondays_until_nth(self):
+        """Test mondays_until_nth function"""
+        # Test with n=2 to get 3 Mondays (including the 0th)
+        result = mondays_until_nth(2)
+
+        # Should return a list of 3 dates
+        self.assertEqual(len(result), 3)
+
+        # All dates should be Mondays (weekday 0)
+        for date in result:
+            self.assertEqual(date.weekday(), 0)  # Monday is 0
+
+        # Dates should be consecutive weeks
+        self.assertEqual(result[1] - result[0], timedelta(days=7))
+        self.assertEqual(result[2] - result[1], timedelta(days=7))