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

[benjamin@sipsolutions.net]

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>
---
 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);
 
 	// 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