os

type FileSystem interface {
	MkdirAll(path string, perm os.FileMode) error
	TempFile(dir, prefix string) (f *os.File, err error)
	Remove(path string)
	TeeReader(r io.Reader, w io.Writer) io.Reader
	Copy(dst io.Writer, src io.Reader) (written int64, err error)
	Rename(oldpath, newpath string) error
	ReadAll(r io.Reader) ([]byte, error)
	WriteFile(filename string, data []byte, perm os.FileMode) error
	Open(name string) (f io.ReadWriteCloser, err error)
	Create(name string) (f io.ReadWriteCloser, err error)
	Exit(code int)
}