get_hierarchy
KUNIT_EXPECT_EQ(test, 10, get_hierarchy(&dom2, 0)->id);
KUNIT_EXPECT_EQ(test, 20, get_hierarchy(&dom2, 1)->id);
KUNIT_EXPECT_EQ(test, 30, get_hierarchy(&dom2, 2)->id);
get_hierarchy(subject->domain, youngest_layer);
get_hierarchy(subject->domain, youngest_layer);