package logx import ( "io" "os" ) var fileSys realFileSystem type ( fileSystem interface { Close(closer io.Closer) error Copy(writer io.Writer, reader io.Reader) (int64, error) Create(name string) (*os.File, error) Open(name string) (*os.File, error) Remove(name string) error } realFileSystem struct{} ) func (fs realFileSystem) Close(closer io.Closer) error { return closer.Close() } func (fs realFileSystem) Copy(writer io.Writer, reader io.Reader) (int64, error) { return io.Copy(writer, reader) } func (fs realFileSystem) Create(name string) (*os.File, error) { return os.Create(name) } func (fs realFileSystem) Open(name string) (*os.File, error) { return os.Open(name) } func (fs realFileSystem) Remove(name string) error { return os.Remove(name) }