unit-tests: Add option to collect active crypto transforms

This will allow us to compare new library versions against previous ones,
so we don't suddenly loose some algorithms like it happened with KDFs
recently after updating OpenSSL to 3.5.1.

src/libstrongswan/tests/suites/test_vectors.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014 Tobias Brunner
+ * Copyright (C) 2014-2025 Tobias Brunner
  * Copyright (C) 2013 Martin Willi
  *
  * Copyright (C) secunet Security Networks AG
@@ -34,6 +34,29 @@ static transform_type_t tfs[] = {
 	KEY_EXCHANGE_METHOD,
 };
 
+static FILE *active_transforms;
+
+START_SETUP(setup)
+{
+	char *path;
+
+	path = getenv("TESTS_ACTIVE_TRANSFORMS");
+	if (path)
+	{
+		active_transforms = fopen(path, "a");
+	}
+}
+END_SETUP
+
+START_TEARDOWN(teardown)
+{
+	if (active_transforms)
+	{
+		fclose(active_transforms);
+	}
+}
+END_TEARDOWN
+
 START_TEST(test_vectors)
 {
 	enumerator_t *enumerator;
@@ -47,12 +70,16 @@ START_TEST(test_vectors)
 	{
 		ck_assert_msg(success, "test vector for %N from '%s' plugin failed",
 					  transform_get_enum_names(tfs[_i]), alg, plugin);
+		if (active_transforms)
+		{
+			fprintf(active_transforms, "%N[%s]\n",
+					transform_get_enum_names(tfs[_i]), alg, plugin);
+		}
 	}
 	thread_cleanup_pop(TRUE);
 }
 END_TEST
 
-
 Suite *vectors_suite_create()
 {
 	Suite *s;
@@ -61,6 +88,7 @@ Suite *vectors_suite_create()
 	s = suite_create("vectors");
 
 	tc = tcase_create("transforms");
+	tcase_add_checked_fixture(tc, setup, teardown);
 	tcase_add_loop_test(tc, test_vectors, 0, countof(tfs));
 	tcase_set_timeout(tc, 30);
 	suite_add_tcase(s, tc);