test-libcrypt-util: print out default for password settings, run make_salt() a few times

Inspired by
https://fedoraproject.org/wiki/Changes/yescrypt_as_default_hashing_method_for_shadow.

src/test/meson.build

@@ -224,7 +224,7 @@ tests += [
         [['src/test/test-os-util.c']],
 
         [['src/test/test-libcrypt-util.c'],
-         [], [], [], '', 'timeout=120'],
+         [], [libcrypt], [], '', 'timeout=120'],
 
         [['src/test/test-escape.c']],
 

src/test/test-libcrypt-util.c

@@ -10,6 +10,29 @@
 #include "tests.h"
 #include "libcrypt-util.h"
 
+static void test_crypt_preferred_method(void) {
+        log_info("/* %s */", __func__);
+
+        log_info("crypt_preferred_method: %s",
+#if HAVE_CRYPT_PREFERRED_METHOD
+                 crypt_preferred_method()
+#else
+                 "(not available)"
+#endif
+        );
+}
+
+static void test_make_salt(void) {
+        log_info("/* %s */", __func__);
+
+        for (int i = 0; i < 10; i++) {
+                _cleanup_free_ char *t;
+
+                assert_se(make_salt(&t) == 0);
+                log_info("%s", t);
+        }
+}
+
 static int test_hash_password(void) {
         log_info("/* %s */", __func__);
 
@@ -93,6 +116,9 @@ int main(int argc, char *argv[]) {
         return log_tests_skipped("crypt_r() causes a buffer overflow on ppc64el, see https://github.com/systemd/systemd/pull/16981#issuecomment-691203787");
 #endif
 
+        test_crypt_preferred_method();
+        test_make_salt();
+
         if (!test_hash_password())
                 return log_tests_skipped("crypt doesn't support yescrypt or sha512crypt");