[PATCH v4 3/4] kunit: Don't crash if no parameters are generated

[David Gow <davidgow@xxxxxxxxxx>]

It's possible that a parameterised test could end up with zero
parameters. At the moment, the test function will nevertheless be called
with NULL as the parameter. Instead, don't try to run the test code, and
just mark the test as SKIPped.

Reported-by: Daniel Latypov <dlatypov@xxxxxxxxxx>
Signed-off-by: David Gow <davidgow@xxxxxxxxxx>
Reviewed-by: Daniel Latypov <dlatypov@xxxxxxxxxx>
---

Changes since v3:
https://lore.kernel.org/linux-kselftest/20211028064154.2301049-3-davidgow@xxxxxxxxxx/
- Fix a change which should've been in patch 4.
- Reverse the order of the if conditional: handle non-parameterised case
  first.

Changes since v2:
https://lore.kernel.org/linux-kselftest/20211027013702.2039566-3-davidgow@xxxxxxxxxx/
- Rework to not share the loop between the parameterised and
  non-parameterised test cases.
  - Suggested by Daniel Latypov.
  - Avoids using a magic non-zero pointer value.

 lib/kunit/test.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/lib/kunit/test.c b/lib/kunit/test.c
index 3bd741e50a2d..f96498ede2cc 100644
--- a/lib/kunit/test.c
+++ b/lib/kunit/test.c
@@ -504,16 +504,18 @@ int kunit_run_tests(struct kunit_suite *suite)
 		struct kunit_result_stats param_stats = { 0 };
 		test_case->status = KUNIT_SKIPPED;
 
-		if (test_case->generate_params) {
+		if (!test_case->generate_params) {
+			/* Non-parameterised test. */
+			kunit_run_case_catch_errors(suite, test_case, &test);
+			kunit_update_stats(&param_stats, test.status);
+		} else {
 			/* Get initial param. */
 			param_desc[0] = '\0';
 			test.param_value = test_case->generate_params(NULL, param_desc);
-		}
 
-		do {
-			kunit_run_case_catch_errors(suite, test_case, &test);
+			while (test.param_value) {
+				kunit_run_case_catch_errors(suite, test_case, &test);
 
-			if (test_case->generate_params) {
 				if (param_desc[0] == '\0') {
 					snprintf(param_desc, sizeof(param_desc),
 						 "param-%d", test.param_index);
@@ -530,11 +532,11 @@ int kunit_run_tests(struct kunit_suite *suite)
 				param_desc[0] = '\0';
 				test.param_value = test_case->generate_params(test.param_value, param_desc);
 				test.param_index++;
-			}
 
-			kunit_update_stats(&param_stats, test.status);
+				kunit_update_stats(&param_stats, test.status);
+			}
+		}
 
-		} while (test.param_value);
 
 		kunit_print_test_stats(&test, param_stats);
 
-- 
2.33.1.1089.g2158813163f-goog