From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EF0E2FA3733 for ; Thu, 17 Oct 2019 12:08:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C5E3320854 for ; Thu, 17 Oct 2019 12:08:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392282AbfJQMIm (ORCPT ); Thu, 17 Oct 2019 08:08:42 -0400 Received: from outgoing-auth-1.mit.edu ([18.9.28.11]:54683 "EHLO outgoing.mit.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1731634AbfJQMIm (ORCPT ); Thu, 17 Oct 2019 08:08:42 -0400 Received: from callcc.thunk.org (guestnat-104-133-0-98.corp.google.com [104.133.0.98] (may be forged)) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id x9HC8Yro023150 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 17 Oct 2019 08:08:34 -0400 Received: by callcc.thunk.org (Postfix, from userid 15806) id B7A5E420458; Thu, 17 Oct 2019 08:08:33 -0400 (EDT) Date: Thu, 17 Oct 2019 08:08:33 -0400 From: "Theodore Y. Ts'o" To: Shuah Khan Cc: Brendan Higgins , Iurii Zaikin , "open list:KERNEL SELFTEST FRAMEWORK" , linux-ext4@vger.kernel.org, adilger.kernel@dilger.ca, KUnit Development Subject: Re: [PATCH linux-kselftest/test v2] ext4: add kunit test for decoding extended timestamps Message-ID: <20191017120833.GA25548@mit.edu> References: <20191010023931.230475-1-yzaikin@google.com> <2f2ea7b0-f683-1cdd-f3f2-ecdf44cb4a97@linuxfoundation.org> <20191011131902.GC16225@mit.edu> <1e6611e6-2fa6-6f7d-bc7f-0bc2243d9342@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1e6611e6-2fa6-6f7d-bc7f-0bc2243d9342@linuxfoundation.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Wed, Oct 16, 2019 at 05:26:29PM -0600, Shuah Khan wrote: > > I don't really buy the argument that unit tests should be deterministic > Possibly, but I would opt for having the ability to feed test data. I strongly believe that unit tests should be deterministic. Non-deterministic tests are essentially fuzz tests. And fuzz tests should be different from unit tests. We want unit tests to run quickly. Fuzz tests need to be run for a large number of passes (perhaps hours) in order to be sure that we've hit any possible bad cases. We want to be able to easily bisect fuzz tests --- preferably, automatically. And any kind of flakey test is hell to bisect. It's bad enough when a test is flakey because of the underlying code. But when a test is flakey because the test inputs are non-deterministic, it's even worse. - Ted