from django.core.signing import b64_decode from django.test import SimpleTestCase, override_settings from django.urls import reverse from .urls import ContactFormViewWithMsg @override_settings(ROOT_URLCONF='messages_tests.urls') class SuccessMessageMixinTests(SimpleTestCase): def test_set_messages_success(self): author = {'name': 'John Doe', 'slug': 'success-msg'} add_url = reverse('add_success_msg') req = self.client.post(add_url, author) # Uncompressed message is stored in the cookie. value = b64_decode( req.cookies['messages'].value.split(":")[0].encode(), ).decode() self.assertIn(ContactFormViewWithMsg.success_message % author, value)