`testgen.parametrize` should be preferred over `metafunc.parametrize`, because it uncollects tests from this module and logs a warning about the inability to parametrize.

```diff
diff --git a/cfme/tests/configure/test_register_appliance.py b/cfme/tests/configure/test_register_appliance.py
index 31a2b38..946facd 100644
--- a/cfme/tests/configure/test_register_appliance.py
+++ b/cfme/tests/configure/test_register_appliance.py
@@ -8,6 +8,7 @@ from cfme.configure import red_hat_updates
 from cfme.web_ui import InfoBlock
 from utils import conf
 from utils.ssh import SSHClient
+from utils.testgen import parametrize
 from utils.wait import wait_for
 
 
@@ -48,7 +49,7 @@ def pytest_generate_tests(metafunc):
             idlist.append(argid)
             argvalues.append(argval)
 
-    metafunc.parametrize(argnames, argvalues, ids=idlist, scope="module")
+    parametrize(metafunc, argnames, argvalues, ids=idlist, scope="module")
```