[PATCH v2 1/7] kunit: Add parent kunit for parameterized test context

David Gow davidgow at google.com
Wed Aug 13 09:17:50 UTC 2025


On Tue, 12 Aug 2025 at 06:17, Marie Zhussupova <marievic at google.com> wrote:
>
> Currently, KUnit parameterized tests lack a mechanism
> to share resources across parameter runs because the
> same `struct kunit` instance is cleaned up and
> reused for each run.
>
> This patch introduces parameterized test context,
> enabling test users to share resources between
> parameter runs. It also allows setting up resources
> that need to be available for all parameter runs only once,
> which is helpful in cases where setup is expensive.
>
> To establish a parameterized test context, this
> patch adds a parent pointer field to `struct kunit`.
> This allows resources added to the parent `struct kunit`
> to be shared and accessible across all parameter runs.
>
> In kunit_run_tests(), the default `struct kunit`
> created is now designated to act as the parameterized
> test context whenever a test is parameterized.
>
> Subsequently, a new `struct kunit` is made
> for each parameter run, and its parent pointer is
> set to the `struct kunit` that holds the
> parameterized test context.
>
> Signed-off-by: Marie Zhussupova <marievic at google.com>
> ---

Thanks, this looks good to me.

Reviewed-by: David Gow <davidgow at google.com>

Cheers,
-- David


>
> Changes in v2:
>
> - Descriptions of the parent pointer in `struct kunit`
>   were changed to be more general, as it could be
>   used to share resources not only between parameter
>   runs but also between test cases in the future.
> - When printing parameter descriptions using
>   test.param_index was changed to param_test.param_index.
> - kunit_cleanup(&test) in kunit_run_tests() was moved
>   inside the parameterized test check.
> - The comments and the commit message were changed to
>   reflect the parameterized testing terminology. See
>   the patch series cover letter change log for the
>   definitions.
>
> ---
>  include/kunit/test.h |  8 ++++++--
>  lib/kunit/test.c     | 34 ++++++++++++++++++++--------------
>  2 files changed, 26 insertions(+), 16 deletions(-)
>
> diff --git a/include/kunit/test.h b/include/kunit/test.h
> index 39c768f87dc9..b47b9a3102f3 100644
> --- a/include/kunit/test.h
> +++ b/include/kunit/test.h
> @@ -268,14 +268,18 @@ struct kunit_suite_set {
>   *
>   * @priv: for user to store arbitrary data. Commonly used to pass data
>   *       created in the init function (see &struct kunit_suite).
> + * @parent: reference to the parent context of type struct kunit that can
> + *         be used for storing shared resources.
>   *
>   * Used to store information about the current context under which the test
>   * is running. Most of this data is private and should only be accessed
> - * indirectly via public functions; the one exception is @priv which can be
> - * used by the test writer to store arbitrary data.
> + * indirectly via public functions; the two exceptions are @priv and @parent
> + * which can be used by the test writer to store arbitrary data and access the
> + * parent context, respectively.
>   */
>  struct kunit {
>         void *priv;
> +       struct kunit *parent;
>
>         /* private: internal use only. */
>         const char *name; /* Read only after initialization! */
> diff --git a/lib/kunit/test.c b/lib/kunit/test.c
> index f3c6b11f12b8..14a8bd846939 100644
> --- a/lib/kunit/test.c
> +++ b/lib/kunit/test.c
> @@ -647,6 +647,7 @@ int kunit_run_tests(struct kunit_suite *suite)
>         struct kunit_case *test_case;
>         struct kunit_result_stats suite_stats = { 0 };
>         struct kunit_result_stats total_stats = { 0 };
> +       const void *curr_param;
>
>         /* Taint the kernel so we know we've run tests. */
>         add_taint(TAINT_TEST, LOCKDEP_STILL_OK);
> @@ -679,37 +680,42 @@ int kunit_run_tests(struct kunit_suite *suite)
>                 } else {
>                         /* Get initial param. */
>                         param_desc[0] = '\0';
> -                       test.param_value = test_case->generate_params(NULL, param_desc);
> +                       /* TODO: Make generate_params try-catch */
> +                       curr_param = test_case->generate_params(NULL, param_desc);
>                         test_case->status = KUNIT_SKIPPED;
>                         kunit_log(KERN_INFO, &test, KUNIT_SUBTEST_INDENT KUNIT_SUBTEST_INDENT
>                                   "KTAP version 1\n");
>                         kunit_log(KERN_INFO, &test, KUNIT_SUBTEST_INDENT KUNIT_SUBTEST_INDENT
>                                   "# Subtest: %s", test_case->name);
>
> -                       while (test.param_value) {
> -                               kunit_run_case_catch_errors(suite, test_case, &test);
> +                       while (curr_param) {
> +                               struct kunit param_test = {
> +                                       .param_value = curr_param,
> +                                       .param_index = ++test.param_index,
> +                                       .parent = &test,
> +                               };
> +                               kunit_init_test(&param_test, test_case->name, test_case->log);
> +                               kunit_run_case_catch_errors(suite, test_case, &param_test);
>
>                                 if (param_desc[0] == '\0') {
>                                         snprintf(param_desc, sizeof(param_desc),
> -                                                "param-%d", test.param_index);
> +                                                "param-%d", param_test.param_index);
>                                 }
>
> -                               kunit_print_ok_not_ok(&test, KUNIT_LEVEL_CASE_PARAM,
> -                                                     test.status,
> -                                                     test.param_index + 1,
> +                               kunit_print_ok_not_ok(&param_test, KUNIT_LEVEL_CASE_PARAM,
> +                                                     param_test.status,
> +                                                     param_test.param_index,
>                                                       param_desc,
> -                                                     test.status_comment);
> +                                                     param_test.status_comment);
>
> -                               kunit_update_stats(&param_stats, test.status);
> +                               kunit_update_stats(&param_stats, param_test.status);
>
>                                 /* Get next param. */
>                                 param_desc[0] = '\0';
> -                               test.param_value = test_case->generate_params(test.param_value, param_desc);
> -                               test.param_index++;
> -                               test.status = KUNIT_SUCCESS;
> -                               test.status_comment[0] = '\0';
> -                               test.priv = NULL;
> +                               curr_param = test_case->generate_params(curr_param, param_desc);
>                         }
> +                       /* TODO: Put this kunit_cleanup into a try-catch. */
> +                       kunit_cleanup(&test);
>                 }
>
>                 kunit_print_attr((void *)test_case, true, KUNIT_LEVEL_CASE);
> --
> 2.51.0.rc0.205.g4a044479a3-goog
>
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