[PATCH bpf-next] selftests/bpf: test_progs option for listing test names

[Jesper Dangaard Brouer <brouer@xxxxxxxxxx>]

The program test_progs have some very useful ability to specify a list of
test name substrings for selecting which tests to run.

This patch add the ability to list the selected test names without running
them. This is practical for seeing which tests gets selected with given
select arguments (which can also contain a exclude list via --name-blacklist).

This output can also be used by shell-scripts in a for-loop:

 for N in $(./test_progs --list -t xdp); do \
   ./test_progs -t $N 2>&1 > result_test_${N}.log & \
 done ; wait

Signed-off-by: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
---
 tools/testing/selftests/bpf/test_progs.c |   20 ++++++++++++++++++++
 tools/testing/selftests/bpf/test_progs.h |    1 +
 2 files changed, 21 insertions(+)

diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
index 1aa5360c427f..36abc3d4a8e2 100644
--- a/tools/testing/selftests/bpf/test_progs.c
+++ b/tools/testing/selftests/bpf/test_progs.c
@@ -367,6 +367,7 @@ enum ARG_KEYS {
 	ARG_VERIFIER_STATS = 's',
 	ARG_VERBOSE = 'v',
 	ARG_GET_TEST_CNT = 'c',
+	ARG_LIST_TEST_NAMES = 'l',
 };
 
 static const struct argp_option opts[] = {
@@ -382,6 +383,8 @@ static const struct argp_option opts[] = {
 	  "Verbose output (use -vv or -vvv for progressively verbose output)" },
 	{ "count", ARG_GET_TEST_CNT, NULL, 0,
 	  "Get number of top-level tests " },
+	{ "list", ARG_LIST_TEST_NAMES, NULL, 0,
+	  "List test names that would run (without running them) " },
 	{},
 };
 
@@ -517,6 +520,9 @@ static error_t parse_arg(int key, char *arg, struct argp_state *state)
 	case ARG_GET_TEST_CNT:
 		env->get_test_cnt = true;
 		break;
+	case ARG_LIST_TEST_NAMES:
+		env->list_test_names = true;
+		break;
 	case ARGP_KEY_ARG:
 		argp_usage(state);
 		break;
@@ -665,6 +671,12 @@ int main(int argc, char **argv)
 				test->test_num, test->test_name))
 			continue;
 
+		if (env.list_test_names) {
+			fprintf(env.stdout, "%s\n", test->test_name);
+			env.succ_cnt++;
+			continue;
+		}
+
 		test->run_test();
 		/* ensure last sub-test is finalized properly */
 		if (test->subtest_name)
@@ -688,9 +700,17 @@ int main(int argc, char **argv)
 			cleanup_cgroup_environment();
 	}
 	stdio_restore();
+
+	if (env.list_test_names) {
+		if (env.succ_cnt == 0)
+			env.fail_cnt = 1;
+		goto out;
+	}
+
 	fprintf(stdout, "Summary: %d/%d PASSED, %d SKIPPED, %d FAILED\n",
 		env.succ_cnt, env.sub_succ_cnt, env.skip_cnt, env.fail_cnt);
 
+out:
 	free_str_set(&env.test_selector.blacklist);
 	free_str_set(&env.test_selector.whitelist);
 	free(env.test_selector.num_set);
diff --git a/tools/testing/selftests/bpf/test_progs.h b/tools/testing/selftests/bpf/test_progs.h
index 0030584619c3..ec31f382e7fd 100644
--- a/tools/testing/selftests/bpf/test_progs.h
+++ b/tools/testing/selftests/bpf/test_progs.h
@@ -67,6 +67,7 @@ struct test_env {
 
 	bool jit_enabled;
 	bool get_test_cnt;
+	bool list_test_names;
 
 	struct prog_test_def *test;
 	FILE *stdout;