Re: [PATCH] Documentation: KUnit: Update filename best practices

[John Hubbard <jhubbard@nvidia.com>]

On 7/17/24 2:00 PM, Kees Cook wrote:
> Based on feedback from Linus[1], change the suggested file naming for
> KUnit tests.
> 
> Link: https://lore.kernel.org/lkml/CAHk-=wgim6pNiGTBMhP8Kd3tsB7_JTAuvNJ=XYd3wPvvk=OHog@mail.gmail.com/ [1]
> Signed-off-by: Kees Cook <kees@kernel.org>
> ---
> Cc: David Gow <davidgow@google.com>
> Cc: Brendan Higgins <brendan.higgins@linux.dev>
> Cc: Rae Moar <rmoar@google.com>
> Cc: Jonathan Corbet <corbet@lwn.net>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: linux-kselftest@vger.kernel.org
> Cc: kunit-dev@googlegroups.com
> Cc: linux-doc@vger.kernel.org
> ---
>   Documentation/dev-tools/kunit/style.rst | 21 +++++++++++++--------
>   1 file changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/Documentation/dev-tools/kunit/style.rst b/Documentation/dev-tools/kunit/style.rst
> index b6d0d7359f00..761dee3f89ca 100644
> --- a/Documentation/dev-tools/kunit/style.rst
> +++ b/Documentation/dev-tools/kunit/style.rst
> @@ -188,15 +188,20 @@ For example, a Kconfig entry might look like:
>   Test File and Module Names
>   ==========================
>   
> -KUnit tests can often be compiled as a module. These modules should be named
> -after the test suite, followed by ``_test``. If this is likely to conflict with
> -non-KUnit tests, the suffix ``_kunit`` can also be used.
> -
> -The easiest way of achieving this is to name the file containing the test suite
> -``<suite>_test.c`` (or, as above, ``<suite>_kunit.c``). This file should be
> -placed next to the code under test.
> +Whether a KUnit test is compiled as a separate module or via an
> +``#include`` in a core kernel source file, the files should be named
> +after the test suite, followed by ``_test``, and live in a ``tests``

I read the previous discussion in the other thread and thought about it.
And ran some kunit tests on baremetal. Delightful! I love this approach.

However! It is rather distinct and not just any old test module. Kunit
has clear conventions and behavior.

As such, I have quickly become convinced that distinct naming is
required here. So I'd like to suggest going with the the suffix:

     _kunit

...unconditionally. After all, sometimes you'll end up with that
anyway, so clearly, the _test suffix isn't strictly required.

And given that we are putting these in tests/ , a _test suffix is
redundant.

Yes?

> +subdirectory to avoid conflicting with regular modules or the core kernel
> +source file names (e.g. for tab-completion). If this would conflict with
> +non-KUnit tests, the suffix ``_kunit`` can be used instead.
> +
> +So for the common case, name the file containing the test suite
> +``tests/<suite>_test.c`` (or, if needed, ``tests/<suite>_kunit.c``). The
> +``tests`` directory should be placed at the same level as the
> +code under test. For example, tests for ``lib/string.c`` live in
> +``lib/tests/string_test.c``.
>   
>   If the suite name contains some or all of the name of the test's parent
>   directory, it may make sense to modify the source filename to reduce redundancy.
> -For example, a ``foo_firmware`` suite could be in the ``foo/firmware_test.c``
> +For example, a ``foo_firmware`` suite could be in the ``tests/foo/firmware_test.c``
>   file.

thanks,
-- 
John Hubbard
NVIDIA