tests: when using pytest mark decorators ensure all fixtures are defined

Decorating a test method directly with a pytest mark seems to break if
the test function does not explicitly define all pytest fixtures it
expects to recieve.

Signed-off-by: Andrew Schoen <aschoen@redhat.com>

tests/functional/tests/test_install.py

@@ -15,7 +15,7 @@ class TestInstall(object):
         assert File(node["conf_path"]).is_file
 
     @pytest.mark.no_docker
-    def test_ceph_command_exists(self, Command):
+    def test_ceph_command_exists(self, Command, node):
         assert Command.exists("ceph")