void do_tests() {
write_file("/rename_test", "Hmm.");
rename("/rename_test", "/ren_test");
ASSERT(file_size("/rename_test") == -1);
ASSERT(read_file("/ren_test") == "Hmm.");
rename("/ren_test", "/single");
ASSERT(file_size("/ren_test") == -1);
ASSERT(read_file("/single/ren_test") == "Hmm.");
rm("/single/ren_test");
}