Re: KUnit file naming conventions (was Re: [GIT PULL] execve updates for v6.11-rc1)

[Kees Cook <kees@kernel.org>]

On Wed, Jul 17, 2024 at 02:28:15PM +0800, David Gow wrote:
> On Wed, 17 Jul 2024 at 11:53, Kees Cook <kees@kernel.org> wrote:
> >
> > On Tue, Jul 16, 2024 at 01:10:41PM -0700, Linus Torvalds wrote:
> > > On Mon, 15 Jul 2024 at 09:21, Kees Cook <kees@kernel.org> wrote:
> > > >
> > > >  fs/exec.c                                   |  49 ++++++++--
> > > >  fs/exec_test.c                              | 141 ++++++++++++++++++++++++++++
> > >
> > > I've pulled this, but *PLEASE* don't do this.
> > >
> > > This screws up my workflow of just using tab-completion for filenames.
> > > As a result, I absolutely abhor anybody who uses the same base-name
> > > for different things.
> > >
> > > No, this is not the first time it happens, and it won't be the last.
> > > And we had that same horrific pattern for fs/binfmt_elf_test.c from
> > > before, and I didn't notice because it's not a core file to me, and I
> > > seldom actually edit it.
> > >
> > > I would suggest that people use the patterns from lib/, which is
> > > admittedly a bit schizophrenic in that you can either use
> > > "lib/kunit/*.c" (probably preferred) or "lib/test_xyz.c".
> > >
> > > (Other subsystems use a "tests" subdirectory, so we do have a lot of
> > > different ways to deal with this).
> > >
> > > Any of those models will keep the unit testing parts clearly separate,
> > > and not mess up basic command line workflows.
> > >
> > > But do *not* use this "*_test.c" naming model. It's the worst of all
> > > possible worlds.
> > >
> > > Please?
> >
> > Oh, sure, no problem! I have no attachment to this convention at all;
> > I was trying to follow the Kunit docs:
> > https://docs.kernel.org/dev-tools/kunit/style.html#test-file-and-module-names
> >
> > If I look at the existing naming, it's pretty scattered:
> >
> > $ git grep '^static struct kunit_suite\b' | cut -d: -f1 | sort -u
> >
> > /test/*          7
> > /tests/*        47
> > *-test.[ch]     27
> > *_test.[ch]     27
> > test-*.c         1
> > test_*.c        10
> > *-kunit.c        1
> > *_kunit.c       17
> > kunit-*.c        2
> > kunit_*.c        1
> >
> > Should we go with "put it all under a 'tests' subdirectory" ?
> 
> I think that's probably best overall. I still think it isn't quite as
> elegant as the suffix, but I'm happy to sacrifice theoretical elegance
> for a practical reason like this.

Okay, I will send a follow-up patch to rename things.

> > So for fs/exec_test.c and fs/binfmt_elf_test.c, perhaps fs/tests/exec.c
> > and fs/tests/binfmt_elf.c respectively?
> 
> We might want to use both the directory and the suffix, e.g.
> fs/tests/exec_test.c, because:
> - it makes sure the module name contains 'test', so it's obvious that
> it's a test and it is less likely to conflict.
> - this matches what drm is doing, and they've got the most tests thus far; and
> - we won't be renaming the file, just moving it, so it's less likely
> to cause friction with workflows, etc.
> 
> On the other hand, it has few disadvantages:
> - we end up with the same prefix issue with module names (e.g., for
> those who have tab completion for modprobe);
> - the module name can be changed in the Makefile anyway; and
> - it's ugly.
> 
> I'm leaning towards tolerating the ugliness and keeping _test suffixes
> on the files, at least for existing tests, but could be persuaded
> otherwise. I'd even grow to accept a test_ prefix if I had to, though
> that'd make my tab completion terribly boring.

I'd been using _test for #included files, and _kunit for kunit modules,
but perhaps this isn't a needed distinction?

> > And for the lib/*_kunit.c files, use lib/tests/*.c ?
> 
> Sounds good to me. I'd rather not put them in lib/kunit unless they're
> actively testing KUnit itself (which, under this scheme, would want to
> be in lib/kunit/tests).

Right -- I didn't want to confuse things between kunit itself and kunit
tests, so I too prefer the "tests" directory name.

> > Then we can update the docs, etc.
> 
> Even if we don't rename existing tests, we'll probably want to update
> these just to avoid making the problem worse.

Sounds good.

-- 
Kees Cook