test: name Mixin with MixinPrefix

pylint understands this and does not report errors about accessing
undefined members.

http://pylint.pycqa.org/en/stable/faq.html#how-do-i-avoid-access-to-undefined-member-messages-in-my-mixin-classes

kedifa/test_kedifa.py

@@ -80,7 +80,8 @@ class KedifaMixin(object):
     self.addCleanup(cleanTestDir)
 
 
-class KedifaMixinCaucase(KedifaMixin):
+class KedifaCaucaseMixin(KedifaMixin):
+
   def createKey(self):
     key = rsa.generate_private_key(
       public_exponent=65537, key_size=2048, backend=default_backend())
@@ -289,7 +290,7 @@ class KedifaMixinCaucase(KedifaMixin):
     return reserved_reference
 
   def setUp(self):
-    super(KedifaMixinCaucase, self).setUp()
+    super(KedifaCaucaseMixin, self).setUp()
     self.createPem()
 
     self.setUpCaucase()
@@ -306,7 +307,7 @@ class KedifaMixinCaucase(KedifaMixin):
     return requests.put(verify=self.ca_crt_pem, *args, **kwargs)
 
 
-class KedifaIntegrationTest(KedifaMixinCaucase, unittest.TestCase):
+class KedifaIntegrationTest(KedifaCaucaseMixin, unittest.TestCase):
   def assertAnyLogEntry(self, entry):
     with open(self.logfile) as fh:
       log_line_list = fh.readlines()