Re: [PATCH 1/2] kunit: add parameter generation macro using description from array

From: David Gow <davidgow@google.com>
To: benjamin@sipsolutions.net
Cc: linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com,
	Benjamin Berg <benjamin.berg@intel.com>
Subject: Re: [PATCH 1/2] kunit: add parameter generation macro using description from array
Date: Wed, 6 Sep 2023 14:45:36 +0800	[thread overview]
Message-ID: <CABVgOSkvVX3D-fgmO-w6eJm7fxQL1T-tVJ6oMVQVhEn98Bmdqw@mail.gmail.com> (raw)
In-Reply-To: <20230904132139.103140-1-benjamin@sipsolutions.net>

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On Mon, 4 Sept 2023 at 21:22, <benjamin@sipsolutions.net> wrote:
>
> From: Benjamin Berg <benjamin.berg@intel.com>
>
> The existing KUNIT_ARRAY_PARAM macro requires a separate function to
> get the description. However, in a lot of cases the description can
> just be copied directly from the array. Add a second macro that
> avoids having to write a static function just for a single strscpy.
>
> Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
> ---

Looks good to me: this will be much more convenient. The actual
implementation looks spot on, just a small comment about the
documentation change.

It may make sense to write some tests and/or some follow-up patches to
existing tests to use this macro, too. I'm just a little wary of
introducing something totally unused. (I'm happy to do these myself if
you don't have time, though.)

Regardless, with the documentation fix, this is:
Reviewed-by: David Gow <davidgow@google.com>

Cheers,
-- David

>  Documentation/dev-tools/kunit/usage.rst |  7 ++++---
>  include/kunit/test.h                    | 19 +++++++++++++++++++
>  2 files changed, 23 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/dev-tools/kunit/usage.rst b/Documentation/dev-tools/kunit/usage.rst
> index c27e1646ecd9..fe8c28d66dfe 100644
> --- a/Documentation/dev-tools/kunit/usage.rst
> +++ b/Documentation/dev-tools/kunit/usage.rst
> @@ -571,8 +571,9 @@ By reusing the same ``cases`` array from above, we can write the test as a
>         {
>                 strcpy(desc, t->str);
>         }
> -       // Creates `sha1_gen_params()` to iterate over `cases`.
> -       KUNIT_ARRAY_PARAM(sha1, cases, case_to_desc);
> +       // Creates `sha1_gen_params()` to iterate over `cases` while using
> +       // the struct member `str` for the case description.
> +       KUNIT_ARRAY_PARAM_DESC(sha1, cases, str);

I'd suggest either getting rid of the case_to_desc function totally
here, or show both the manual KUNIT_ARRAY_PARAM() example, and then
point out explicitly that KUNIT_ARRAY_PARAM_DESC() can replace it.

Otherwise we end up with a vestigial function which doesn't do
anything and is confusing.

>
>         // Looks no different from a normal test.
>         static void sha1_test(struct kunit *test)
> @@ -588,7 +589,7 @@ By reusing the same ``cases`` array from above, we can write the test as a
>         }
>
>         // Instead of KUNIT_CASE, we use KUNIT_CASE_PARAM and pass in the
> -       // function declared by KUNIT_ARRAY_PARAM.
> +       // function declared by KUNIT_ARRAY_PARAM or KUNIT_ARRAY_PARAM_DESC.
>         static struct kunit_case sha1_test_cases[] = {
>                 KUNIT_CASE_PARAM(sha1_test, sha1_gen_params),
>                 {}
> diff --git a/include/kunit/test.h b/include/kunit/test.h
> index 68ff01aee244..f60d11e41855 100644
> --- a/include/kunit/test.h
> +++ b/include/kunit/test.h
> @@ -1516,6 +1516,25 @@ do {                                                                            \
>                 return NULL;                                                                    \
>         }
>
> +/**
> + * KUNIT_ARRAY_PARAM_DESC() - Define test parameter generator from an array.
> + * @name:  prefix for the test parameter generator function.
> + * @array: array of test parameters.
> + * @desc_member: structure member from array element to use as description
> + *
> + * Define function @name_gen_params which uses @array to generate parameters.
> + */
> +#define KUNIT_ARRAY_PARAM_DESC(name, array, desc_member)                                       \
> +       static const void *name##_gen_params(const void *prev, char *desc)                      \
> +       {                                                                                       \
> +               typeof((array)[0]) *__next = prev ? ((typeof(__next)) prev) + 1 : (array);      \
> +               if (__next - (array) < ARRAY_SIZE((array))) {                                   \
> +                       strscpy(desc, __next->desc_member, KUNIT_PARAM_DESC_SIZE);              \
> +                       return __next;                                                          \
> +               }                                                                               \
> +               return NULL;                                                                    \
> +       }
> +
>  // TODO(dlatypov@google.com): consider eventually migrating users to explicitly
>  // include resource.h themselves if they need it.
>  #include <kunit/resource.h>
> --
> 2.41.0
>
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