kunit: Don't crash if no parameters are generated

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@google.com>
Signed-off-by: David Gow <davidgow@google.com>
Reviewed-by: Daniel Latypov <dlatypov@google.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

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);