text: 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");
  }
  