VirtualFileSystem: {
    readdir: ((path: string) => string[]);
    root: string;
    stat: ((path: string) => FileStat);
    type: FileSystemBackend;
    exists(path: string): boolean;
    readFile(path: string): Buffer;
    resolve(...path: string[]): string;
    writeFile(path: string, content: string | Buffer): void;
}