io/fs adapters?

aind...@gmail.com

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Mar 27, 2021, 11:09:12 PM3/27/21

to golang-nuts

For testing library functions that accept fs.FS, I've been creating mock FS implementations. However, I'm surprised by the amount of code I've had to write for something like an FS with a single file in it. See below:

type singleFileFS struct {

f stringFile

}

func (r singleFileFS) Open(name string) (fs.File, error) { return nil, nil }

func (r singleFileFS) Stat(name string) (fs.FileInfo, error) { return r, nil }

func (r singleFileFS) Name() string { return "." }

func (r singleFileFS) Size() int64 { return -1 }

func (r singleFileFS) Mode() (m fs.FileMode) { return }

func (r singleFileFS) ModTime() (t time.Time) { return }

func (r singleFileFS) IsDir() bool { return true }

func (r singleFileFS) Sys() interface{} { return nil }

func (r singleFileFS) ReadDir(string) ([]fs.DirEntry, error) { return []fs.DirEntry{r.f}, nil }

func (r singleFileFS) ReadFile(name string) ([]byte, error) { return r.f.body, nil }

type stringFile struct {

name string

body []byte

}

func (s stringFile) Stat() (fs.FileInfo, error) { return s, nil }

func (s stringFile) Name() string { return s.name }

func (s stringFile) Size() int64 { return int64(len(s.body)) }

func (s stringFile) Mode() (m fs.FileMode) { return }

func (s stringFile) Type() (m fs.FileMode) { return }

func (s stringFile) ModTime() (t time.Time) { return }

func (s stringFile) IsDir() (false bool) { return }

func (s stringFile) Sys() (i interface{}) { return }

func (s stringFile) Read([]byte) (i int, e error) { return }

func (s stringFile) Close() (err error) { return }

func (s stringFile) Info() (fs.FileInfo, error) { return s, nil }

Does anyone have any tips for creating a smaller version of this kind of adapter? Or are there any FS adapter libraries that can help with this sort of thing?

Thanks,

Akhil