test: skip tests if cgroup isn't mounted

Debian builds in a chroot without cgroup mounted, so tests expecting
to access cgroup will fail with ENOMEDIUM, so skip the tests in that
situation.

src/test/test-cgroup-util.c

@@ -338,7 +338,7 @@ static void test_cg_tests(void) {
 
         r = cg_unified();
         if (r == -ENOMEDIUM) {
-                log_notice_errno(r, "Skipping cg hierarchy tests: %m");
+                log_tests_skipped("cgroup not mounted");
                 return;
         }
         assert_se(r >= 0);

src/test/test-cgroup.c

@@ -47,10 +47,11 @@ static void test_cg_create(void) {
         int r;
 
         r = cg_unified_cached(false);
-        if (r < 0) {
-                log_info_errno(r, "Skipping %s: %m", __func__);
+        if (r == -ENOMEDIUM) {
+                log_tests_skipped("cgroup not mounted");
                 return;
         }
+        assert_se(r >= 0);
 
         _cleanup_free_ char *here = NULL;
         assert_se(cg_pid_get_path_shifted(0, NULL, &here) >= 0);

src/test/test-condition.c

@@ -129,6 +129,11 @@ static void test_condition_test_control_group_hierarchy(void) {
         int r;
 
         r = cg_unified();
+        if (r == -ENOMEDIUM) {
+                log_tests_skipped("cgroup not mounted");
+                return;
+        }
+        assert_se(r >= 0);
 
         condition = condition_new(CONDITION_CONTROL_GROUP_CONTROLLER, "v1", false, false);
         assert_se(condition);
@@ -148,10 +153,11 @@ static void test_condition_test_control_group_controller(void) {
         int r;
 
         r = cg_unified();
-        if (r < 0) {
-                log_notice_errno(r, "Skipping ConditionControlGroupController tests: %m");
+        if (r == -ENOMEDIUM) {
+                log_tests_skipped("cgroup not mounted");
                 return;
         }
+        assert_se(r >= 0);
 
         /* Invalid controllers are ignored */
         condition = condition_new(CONDITION_CONTROL_GROUP_CONTROLLER, "thisisnotarealcontroller", false, false);