UPD: added dedicated test template for email test.

dav_base/templates/dav_base/tests/mail.txt

@@ -0,0 +1 @@
+This template is used by the automatic software tests.

dav_base/tests/test_emails.py

@@ -5,6 +5,8 @@ from django.test import SimpleTestCase
 from ..emails import AbstractMail
 from .generic import EmailTestMixin
 
+MAIL_TEMPLATE = 'dav_base/tests/mail.txt'
+
 
 class TestCase(EmailTestMixin, SimpleTestCase):
     def test_no_template_configured(self):
@@ -17,7 +19,7 @@ class TestCase(EmailTestMixin, SimpleTestCase):
 
     def test_no_get_recipients_implemented(self):
         class ConcreteMail(AbstractMail):
-            _template_name = 'dav_base/base.html'
+            _template_name = MAIL_TEMPLATE
 
         email = ConcreteMail()
         with self.assertRaises(NotImplementedError):
@@ -27,7 +29,7 @@ class TestCase(EmailTestMixin, SimpleTestCase):
         recipient = 'root@localhost'
 
         class ConcreteMail(AbstractMail):
-            _template_name = 'dav_base/base.html'
+            _template_name = MAIL_TEMPLATE
 
             def _get_recipients(self):
                 return [recipient]