Pass tempest return code back to caller

Use case: I'm running refstack-client in a tox job, which always appears
to succeed, even when the test fails.

Currently, unless it throws a backtrace on it's own, the refstack-client
script always returns successfully, even when the tempest job it's
running fails.

This change simply passes non-zero return codes back through as the
refstack-client's return code.

Only the test() method was affected here, because it's the only
externally callable function that uses subprocess. Other functions can
now return non-zero return codes as well.

Change-Id: I0ce786babcbee47da1c038a3478bcd4de0dff16e

refstack-client

@@ -28,4 +28,4 @@ from refstack_client import refstack_client
 if __name__ == '__main__':
     args = refstack_client.parse_cli_args()
     test = refstack_client.RefstackClient(args)
-    getattr(test, args.func)()
+    raise SystemExit(getattr(test, args.func)())

refstack_client/refstack_client.py

@@ -459,6 +459,7 @@ class RefstackClient:
         else:
             self.logger.error("Problem executing Tempest script. Exit code %d",
                               process.returncode)
+        return process.returncode
 
     def upload(self):
         '''Perform upload to RefStack URL.'''