Re: [PATCH v2 6/7] kunit: Add example parameterized test with direct dynamic parameter array setup

On Tue, 12 Aug 2025 at 06:18, Marie Zhussupova marievic@google.com wrote:

Introduce example_params_test_with_init_dynamic_arr(). This new KUnit test demonstrates directly assigning a dynamic parameter array, using the kunit_register_params_array() macro, to a parameterized test context.

It highlights the use of param_init() and param_exit() for initialization and exit of a parameterized test, and their registration to the test case with KUNIT_CASE_PARAM_WITH_INIT().

Signed-off-by: Marie Zhussupova marievic@google.com

I really like this example now. Thanks!

Reviewed-by: David Gow davidgow@google.com

Cheers, -- David

Changes in v2:

• kunit_array_gen_params() is now explicitly passed to KUNIT_CASE_PARAM_WITH_INIT() to be consistent with the parameterized test being defined by the existence of the generate_params() function.
• param_init() was changed to output a log at the start of a parameterized test.
• The parameter array was changed to be allocated using kunit_kmalloc_array(), a KUnit memory allocation API, as that would be the preferred/easier method. To still demonstrate a use of param_exit(), it now outputs a log at the end of the parameterized test.
• 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.

---

lib/kunit/kunit-example-test.c | 104 +++++++++++++++++++++++++++++++++ 1 file changed, 104 insertions(+)

diff --git a/lib/kunit/kunit-example-test.c b/lib/kunit/kunit-example-test.c index f2819ee58965..ff21511889a4 100644 --- a/lib/kunit/kunit-example-test.c +++ b/lib/kunit/kunit-example-test.c @@ -393,6 +393,107 @@ static void example_params_test_with_init(struct kunit *test) kunit_put_resource(res); }

+/*

• • Helper function to create a parameter array of Fibonacci numbers. This example
• • highlights a parameter generation scenario that is:
• • 1. Not feasible to fully pre-generate at compile time.
• • 2. Challenging to implement with a standard generate_params() function,
• • as it only provides the previous parameter, while Fibonacci requires
• • access to two preceding values for calculation.
• */

+static void *make_fibonacci_params(struct kunit *test, size_t seq_size) +{

•   int *seq;
  

•   if (seq_size <= 0)
  

•           return NULL;
  

•   /*
  

•    * Using kunit_kmalloc_array here ties the lifetime of the array to
  

•    * the parameterized test i.e. it will get automatically cleaned up
  

•    * by KUnit after the parameterized test finishes.
  

•    */
  

•   seq = kunit_kmalloc_array(test, seq_size, sizeof(int), GFP_KERNEL);
  

•   if (!seq)
  

•           return NULL;
  

•   if (seq_size >= 1)
  

•           seq[0] = 0;
  

•   if (seq_size >= 2)
  

•           seq[1] = 1;
  

•   for (int i = 2; i < seq_size; i++)
  

•           seq[i] = seq[i - 1] + seq[i - 2];
  

•   return seq;
  

+}

+/*

• • This is an example of a function that provides a description for each of the
• • parameters.
• */

+static void example_param_dynamic_arr_get_desc(struct kunit *test, const void *p, char *desc) +{

•   const int *fib_num = p;
  

•   snprintf(desc, KUNIT_PARAM_DESC_SIZE, "fibonacci param: %d", *fib_num);
  

+}

+/*

• • Example of a parameterized test param_init() function that registers a dynamic
• • array of parameters.
• */

+static int example_param_init_dynamic_arr(struct kunit *test) +{

•   size_t seq_size;
  

•   int *fibonacci_params;
  

•   kunit_info(test, "initializing parameterized test\n");
  

•   seq_size = 6;
  

•   fibonacci_params = make_fibonacci_params(test, seq_size);
  

•   if (!fibonacci_params)
  

•           return -ENOMEM;
  

•   /*
  

•    * Passes the dynamic parameter array information to the parameterized test
  

•    * context struct kunit. The array and its metadata will be stored in
  

•    * test->parent->params_array. The array itself will be located in
  

•    * params_data.params.
  

•    *
  

•    * Note that you will need to pass kunit_array_gen_params() as the
  

•    * generator function to KUNIT_CASE_PARAM_WITH_INIT() when registering
  

•    * a parameter array this route.
  

•    */
  

•   kunit_register_params_array(test, fibonacci_params, seq_size,
  

•                               example_param_dynamic_arr_get_desc);
  

•   return 0;
  

+}

+/*

• • Example of a parameterized test param_exit() function that outputs a log
• • at the end of the parameterized test. It could also be used for any other
• • teardown logic.
• */

+static void example_param_exit_dynamic_arr(struct kunit *test) +{

•   kunit_info(test, "exiting parameterized test\n");
  

+}

+/*

• • Example of test that uses the registered dynamic array to perform assertions
• • and expectations.
• */

+static void example_params_test_with_init_dynamic_arr(struct kunit *test) +{

•   const int *param = test->param_value;
  

•   int param_val;
  

•   /* By design, param pointer will not be NULL. */
  

•   KUNIT_ASSERT_NOT_NULL(test, param);
  

•   param_val = *param;
  

•   KUNIT_EXPECT_EQ(test, param_val - param_val, 0);
  

+}

/*

• Here we make a list of all the test cases we want to add to the test suite
• below.

@@ -414,6 +515,9 @@ static struct kunit_case example_test_cases[] = { KUNIT_CASE_PARAM(example_params_test, example_gen_params), KUNIT_CASE_PARAM_WITH_INIT(example_params_test_with_init, kunit_array_gen_params, example_param_init, NULL),

•   KUNIT_CASE_PARAM_WITH_INIT(example_params_test_with_init_dynamic_arr,
  

•                              kunit_array_gen_params, example_param_init_dynamic_arr,
  

•                              example_param_exit_dynamic_arr),
    KUNIT_CASE_SLOW(example_slow_test),
    {}
  

};

2.51.0.rc0.205.g4a044479a3-goog