linux-kernel - Re: [PATCH v7 0/3] scanf: convert self-test to KUnit

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Message-ID: <Z69GLMVPCuKKz1gk@pathway.suse.cz>
Date: Fri, 14 Feb 2025 14:33:32 +0100
From: Petr Mladek <pmladek@...e.com>
To: Tamir Duberstein <tamird@...il.com>
Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	David Gow <davidgow@...gle.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Rasmus Villemoes <linux@...musvillemoes.dk>,
	Sergey Senozhatsky <senozhatsky@...omium.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Shuah Khan <shuah@...nel.org>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v7 0/3] scanf: convert self-test to KUnit

On Wed 2025-02-12 11:54:52, Tamir Duberstein wrote:
> On Tue, Feb 11, 2025 at 12:26 PM Tamir Duberstein <tamird@...il.com> wrote:
> >
> > > Is it me who cut something or the above missing this information (total tests)?
> > > If the latter, how are we supposed to answer to the question if the failed test
> > > is from new bunch of cases I hypothetically added or regression of the existing
> > > ones? Without this it seems like I need to go through all failures. OTOH it may
> > > be needed anyway as failing test case needs an investigation.
> >
> > I assume you mean missing from the new output. Yeah, KUnit doesn't do
> > this counting. Instead you get the test name in the failure message:
> >
> > > > > > > >     vsscanf("0 1e 3e43 31f0 0 0 5797 9c70", "%1hx %2hx %4hx %4hx %1hx %1hx %4hx %4hx", ...) expected 837828163 got 1044578334
> > > > > > > >             not ok 1 " "
> > > > > > > >         # numbers_list_field_width_val_width: ASSERTION FAILED at lib/scanf_kunit.c:92
> >
> > I think maybe you're saying: what if I add a new assertion (rather
> > than a new test case), and I start getting failure reports - how do I
> > know if the reporter is running old or new test code?
> >
> > In an ideal world the message above would give you all the information
> > you need by including the line number from the test. This doesn't
> > quite work out in this case because of the various test helper
> > functions; you end up with a line number in the test helper rather
> > than in the test itself. We could fix that by passing around __FILE__
> > and __LINE__ (probably by wrapping the test helpers in a macro). What
> > do you think?

I am not sure how many changes are needed to wrap the test helpers in
a macro.

> I gave this a try locally, and it produced this output:
> 
> >     # numbers_list_field_width_val_width: ASSERTION FAILED at lib/scanf_kunit.c:94
> > lib/scanf_kunit.c:555: vsscanf("0 1e 3e43 31f0 0 0 5797 9c70", "%1hx %2hx %4hx %4hx %1hx %1hx %4hx %4hx", ...) expected 837828163 got 1044578334
> >         not ok 1 " "
> >     # numbers_list_field_width_val_width: ASSERTION FAILED at lib/scanf_kunit.c:94
> > lib/scanf_kunit.c:555: vsscanf("dc2:1c:0:3531:2621:5172:1:7", "%3hx:%2hx:%1hx:%4hx:%4hx:%4hx:%1hx:%1hx", ...) expected 892403712 got 28
> >         not ok 2 ":"
> >     # numbers_list_field_width_val_width: ASSERTION FAILED at lib/scanf_kunit.c:94
> > lib/scanf_kunit.c:555: vsscanf("e083,8f6e,b,70ca,1,1,aab1,10e4", "%4hx,%4hx,%1hx,%4hx,%1hx,%1hx,%4hx,%4hx", ...) expected 1892286475 got 757614
> >         not ok 3 ","
> >     # numbers_list_field_width_val_width: ASSERTION FAILED at lib/scanf_kunit.c:94
> > lib/scanf_kunit.c:555: vsscanf("2e72-8435-1-2fc-7cbd-c2f1-7158-2b41", "%4hx-%4hx-%1hx-%3hx-%4hx-%4hx-%4hx-%4hx", ...) expected 50069505 got 99381
> >         not ok 4 "-"
> >     # numbers_list_field_width_val_width: ASSERTION FAILED at lib/scanf_kunit.c:94
> > lib/scanf_kunit.c:555: vsscanf("403/0/17/1/11e7/1/1fe8/34ba", "%3hx/%1hx/%2hx/%1hx/%4hx/%1hx/%4hx/%4hx", ...) expected 65559 got 1507328
> >         not ok 5 "/"

But I really like that the error message shows the exact line of the
caller. IMHO, it is very helpful in this module. I like it.

IMHO, it also justifies removing the pr_debug() messages (currently 1st patch).

> Andy, Petr: what do you think? I've added this (and the original
> output, as you requested) to the cover letter for when I reroll v8
> (not before next week).

I suggest, to do the switch into macros in the 1st patch.
Remove the obsolete pr_debug() lines in 2nd patch.
Plus two more patches switching the module to kunit test.

I am personally fine with this change.

Best Regards,
Petr