[PATCH 2/2] kunit: Allow to filter entries from zero terminated arrays

[Michal Wajdeczko <michal.wajdeczko@xxxxxxxxx>]

In some cases we may want to generate params based on existing
zero terminated array, but with some entries filtered out.
Extend macro KUNIT_ZERO_ARRAY_PARAM to accept filter function
and provide example how to use it.

$ ./tools/testing/kunit/kunit.py run \
    --kunitconfig ./lib/kunit/.kunitconfig *.example_params*

[ ] Starting KUnit Kernel (1/1)...
[ ] ============================================================
[ ] ========================= example  =========================
[ ] =================== example_params_test  ===================
[ ] [SKIPPED] example value 3
[ ] [PASSED] example value 2
[ ] [PASSED] example value 1
[ ] [SKIPPED] example value 0
[ ] =============== [PASSED] example_params_test ===============
[ ] =================== example_params_test  ===================
[ ] [SKIPPED] example value 3
[ ] [PASSED] example value 2
[ ] [PASSED] example value 1
[ ] =============== [PASSED] example_params_test ===============
[ ] =================== example_params_test  ===================
[ ] [PASSED] example value 2
[ ] [PASSED] example value 1
[ ] =============== [PASSED] example_params_test ===============
[ ] ===================== [PASSED] example =====================
[ ] ============================================================
[ ] Testing complete. Ran 9 tests: passed: 6, skipped: 3

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@xxxxxxxxx>
Cc: David Gow <davidgow@xxxxxxxxxx>
Cc: Rae Moar <rmoar@xxxxxxxxxx>
---
 include/kunit/test.h           | 19 +++++++++++++++++--
 lib/kunit/kunit-example-test.c |  9 +++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/include/kunit/test.h b/include/kunit/test.h
index 280113ceb6a6..8a87d1ce37e0 100644
--- a/include/kunit/test.h
+++ b/include/kunit/test.h
@@ -1515,20 +1515,24 @@ do {									       \
 	}
 
 /**
- * KUNIT_ZERO_ARRAY_PARAM() - Define test parameter generator from a zero terminated array.
+ * KUNIT_FILTERED_ZERO_ARRAY_PARAM() - Define test parameter generator from a zero terminated array.
  * @name:  prefix for the test parameter generator function.
  * @array: zero terminated array of test parameters.
  * @get_desc: function to convert param to description; NULL to use default
+ * @filter: function to filter out unwanted params (like duplicates); can be NULL
  *
  * Define function @name_gen_params which uses zero terminated @array to generate parameters.
  */
-#define KUNIT_ZERO_ARRAY_PARAM(name, array, get_desc)						\
+#define KUNIT_FILTERED_ZERO_ARRAY_PARAM(name, array, get_desc, filter)				\
 	static const void *name##_gen_params(const void *prev, char *desc)			\
 	{											\
 		typeof((array)[0]) *__prev = prev;						\
 		typeof(__prev) __next = __prev ? __prev + 1 : (array);				\
 		void (*__get_desc)(typeof(__next), char *) = get_desc;				\
+		bool (*__filter)(typeof(__prev), typeof(__next)) = filter;			\
 		for (; memchr_inv(__next, 0, sizeof(*__next)); __prev = __next++) {		\
+			if (__filter && !__filter(__prev, __next))				\
+				continue;							\
 			if (__get_desc)								\
 				__get_desc(__next, desc);					\
 			return __next;								\
@@ -1536,6 +1540,17 @@ do {									       \
 		return NULL;									\
 	}
 
+/**
+ * KUNIT_ZERO_ARRAY_PARAM() - Define test parameter generator from a zero terminated array.
+ * @name:  prefix for the test parameter generator function.
+ * @array: zero terminated array of test parameters.
+ * @get_desc: function to convert param to description; NULL to use default
+ *
+ * Define function @name_gen_params which uses zero terminated @array to generate parameters.
+ */
+#define KUNIT_ZERO_ARRAY_PARAM(name, array, get_desc)	\
+	KUNIT_FILTERED_ZERO_ARRAY_PARAM(name, array, get_desc, NULL)
+
 // TODO(dlatypov@xxxxxxxxxx): consider eventually migrating users to explicitly
 // include resource.h themselves if they need it.
 #include <kunit/resource.h>
diff --git a/lib/kunit/kunit-example-test.c b/lib/kunit/kunit-example-test.c
index ad9ebcfd513e..a3268754392c 100644
--- a/lib/kunit/kunit-example-test.c
+++ b/lib/kunit/kunit-example-test.c
@@ -201,8 +201,16 @@ static void example_param_get_desc(const struct example_param *p, char *desc)
 	snprintf(desc, KUNIT_PARAM_DESC_SIZE, "example value %d", p->value);
 }
 
+static bool example_param_filter(const struct example_param *prev,
+				 const struct example_param *next)
+{
+	return next->value < 3;
+}
+
 KUNIT_ARRAY_PARAM(example, example_params_array, example_param_get_desc);
 KUNIT_ZERO_ARRAY_PARAM(example_zero, example_params_array, example_param_get_desc);
+KUNIT_FILTERED_ZERO_ARRAY_PARAM(example_filter, example_params_array, example_param_get_desc,
+				example_param_filter);
 
 /*
  * This test shows the use of params.
@@ -248,6 +256,7 @@ static struct kunit_case example_test_cases[] = {
 	KUNIT_CASE(example_static_stub_test),
 	KUNIT_CASE_PARAM(example_params_test, example_gen_params),
 	KUNIT_CASE_PARAM(example_params_test, example_zero_gen_params),
+	KUNIT_CASE_PARAM(example_params_test, example_filter_gen_params),
 	KUNIT_CASE_SLOW(example_slow_test),
 	{}
 };
-- 
2.25.1