Catch SystemExit for parse args

If you have a test with parse args it fails with no error
messages.  This change throws an exception.

Change-Id: I545aba346620a352fe570d394dbd4d6bd2daa995

Author: TerryHowe

openstackclient/tests/utils.py

@@ -73,7 +73,10 @@ def setUp(self):
 
     def check_parser(self, cmd, args, verify_args):
         cmd_parser = cmd.get_parser('check_parser')
-        parsed_args = cmd_parser.parse_args(args)
+        try:
+            parsed_args = cmd_parser.parse_args(args)
+        except SystemExit:
+            raise Exception("Argument parse failed")
         for av in verify_args:
             attr, value = av
             if attr: