pytest: Migrate xunit-style setups to Pytest fixtures

Even though Pytest supports xunit style setups, unittest and nose
tests, this support is limited and may be dropped in the future
releases. Worst of all is that the mixing of various test
frameworks results in weird conflicts and of course, is not widely
tested.

This is a part of work to remove the mixing of test idioms in the
IPA's test suite:
1) replace xunit style
2) employ the fixtures' interdependencies

Related: https://pagure.io/freeipa/issue/7989
Signed-off-by: Stanislav Levin <slev@altlinux.org>
Reviewed-By: Christian Heimes <cheimes@redhat.com>

ipatests/test_ipaserver/test_install/test_installer.py

@@ -9,6 +9,8 @@ from abc import ABCMeta, abstractproperty
 from collections import namedtuple
 import itertools
 
+import pytest
+
 from ipatests.util import assert_equal
 from ipaserver.install.ipa_replica_install import ReplicaInstall
 
@@ -23,16 +25,18 @@ class InstallerTestBase(six.with_metaclass(ABCMeta, object)):
     def tested_cls(self):
         return None
 
-    def setup_class(self):
+    @pytest.fixture(autouse=True, scope="class")
+    def installer_setup(self, request):
         """Initializes the tested class so that it can be used later on
         """
-        self.tested_cls.make_parser()
+        cls = request.cls
+        cls.tested_cls.make_parser()
         assert \
-            getattr(self.tested_cls, 'option_parser', False), \
+            getattr(cls.tested_cls, 'option_parser', False), \
             ("Unable to generate option parser for {}"
-             .format(self.tested_cls.__name__))
+             .format(cls.tested_cls.__name__))
 
-        self._populate_opts_dict()
+        cls._populate_opts_dict()
 
     @classmethod
     def _populate_opts_dict(cls):