UPD: More and better tests.

dav_base/tests/generic.py

@@ -3,6 +3,7 @@ import os
 from django.apps import apps
 from django.contrib.auth.models import AbstractUser
 from django.contrib.staticfiles.testing import StaticLiveServerTestCase
+from django.core import mail as django_mail
 from django.test import SimpleTestCase, TestCase, tag
 from django.urls import reverse
 from selenium import webdriver
@@ -44,6 +45,15 @@ class EmailTestMixin(object):
     email_base_url = 'http://localhost'
     email_subject_prefix = '[Test]'
 
+    def get_mail_for_user(self, user):
+        recipient = '"{fullname}" <{email}>'.format(fullname=user.get_full_name(), email=user.email)
+        mails = []
+        for mail in django_mail.outbox:
+            if recipient in mail.recipients():
+                mails.append(mail)
+
+        return mails
+
     def assertSender(self, mail):
         self.assertEqual(mail.from_email, self.email_sender)