testfs

README

testfs

A simple fs.FS which is contained in a test (using testing.TB's TempDir()) and with a few helper methods.

PS: This lib only works on Go 1.16+.

Example

func TestSomething(t *testing.T) {
	tmpfs := testfs.New(t)
	testfile := "foo/bar/foobar"
	_ = tmpfs.MkdirAll(filepath.Dir(testfile), 0o764)
	_ = tmpfs.WriteFile(testfile, []byte("example"), 0o644)

	// you can now use tmpfs as a fs.FS...
	// fs.WalkDir(tmpfs, ".", func(path string, d fs.DirEntry, err error) error { return nil })

	// and read files of course:
	bts, _ := fs.ReadFile(tmpfs, testfile)
	fmt.Println(string(bts))
}

Why

The idea is to able to test code that use a fs.FS, without having to, for example, commit a bunch of files inside testdata and without using in-memory implementation that might not do the same thing as a real FS.

This is a real FS, it only limits itself to a temporary directory and cleans after itself once the test is done. You also get a couple of helper methods to create the structure you need.

Other options

If you don't mind testing against an in-memory implementation, the native fstest.MemFS is a good option.

Documentation

Overview

Package testfs provides a simple fs.FS which is contained in a test (using testing.TB's TempDir) and with a few helper methods.

The temporary FS is auto-cleaned once the test and all its children finish.

Index

• Variables
• type FS
  • func New(tb testing.TB) FS
  • func (t FS) MkdirAll(path string, perm os.FileMode) error
  • func (t FS) Open(name string) (fs.File, error)
  • func (t FS) Path() string
  • func (t FS) WriteFile(name string, data []byte, perm os.FileMode) error

Examples

• New

Variables

var ErrOutsideFS = fmt.Errorf("path is outside test fs root folder")

ErrOutsideFS happens when the user tries to handle files outside of the FS's root path.

Types

type FS

type FS struct {
	FS fs.FS
	// contains filtered or unexported fields
}

FS is a fs.FS made for testing only.

func New

func New(tb testing.TB) FS

New creates a new FS using the tb.TempDir as root.

Example

tmpfs := New(&testing.T{})
_ = tmpfs.MkdirAll("foo/bar", 0o764)
_ = tmpfs.WriteFile("foo/bar/foobar", []byte("example"), 0o644)
bts, _ := fs.ReadFile(tmpfs, "foo/bar/foobar")
fmt.Println(string(bts))

Output:

example

func (FS) MkdirAll

func (t FS) MkdirAll(path string, perm os.FileMode) error

MkdirAll creates the dir and all the necessary parents into FS.

func (FS) Open

func (t FS) Open(name string) (fs.File, error)

Open opens the named file.

func (FS) Path

func (t FS) Path() string

Path returns the FS root path.

func (FS) WriteFile

func (t FS) WriteFile(name string, data []byte, perm os.FileMode) error

WriteFile writes a file to FS.