ASSERT_EQ(childpath, nullptr);
    TF_StringStreamDone(children);

    TF_FileStatistics stats;
    TF_FileStat(filepath.c_str(), &stats, s);
    ASSERT_EQ(stats.length, strlen(data));
    ASSERT_FALSE(stats.is_directory);
    ASSERT_GT(stats.mtime_nsec, 0);

    // Trying to delete a non-empty directory should fail.
    TF_DeleteDir(dirpath.c_str(), s);