package standard library
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Published: Jul 2, 2024 License: BSD-3-Clause Imports: 10 Imported by: 120



Package fstest implements support for testing implementations and users of file systems.



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func TestFS

func TestFS(fsys fs.FS, expected ...string) error

TestFS tests a file system implementation. It walks the entire tree of files in fsys, opening and checking that each file behaves correctly. It also checks that the file system contains at least the expected files. As a special case, if no expected files are listed, fsys must be empty. Otherwise, fsys must contain at least the listed files; it can also contain others. The contents of fsys must not change concurrently with TestFS.

If TestFS finds any misbehaviors, it returns an error reporting all of them. The error text spans multiple lines, one per detected misbehavior.

Typical usage inside a test is:

if err := fstest.TestFS(myFS, "file/that/should/be/present"); err != nil {


type MapFS

type MapFS map[string]*MapFile

A MapFS is a simple in-memory file system for use in tests, represented as a map from path names (arguments to Open) to information about the files or directories they represent.

The map need not include parent directories for files contained in the map; those will be synthesized if needed. But a directory can still be included by setting the [MapFile.Mode]'s fs.ModeDir bit; this may be necessary for detailed control over the directory's fs.FileInfo or to create an empty directory.

File system operations read directly from the map, so that the file system can be changed by editing the map as needed. An implication is that file system operations must not run concurrently with changes to the map, which would be a race. Another implication is that opening or reading a directory requires iterating over the entire map, so a MapFS should typically be used with not more than a few hundred entries or directory reads.

func (MapFS) Glob

func (fsys MapFS) Glob(pattern string) ([]string, error)

func (MapFS) Open

func (fsys MapFS) Open(name string) (fs.File, error)

Open opens the named file.

func (MapFS) ReadDir

func (fsys MapFS) ReadDir(name string) ([]fs.DirEntry, error)

func (MapFS) ReadFile

func (fsys MapFS) ReadFile(name string) ([]byte, error)

func (MapFS) Stat

func (fsys MapFS) Stat(name string) (fs.FileInfo, error)

func (MapFS) Sub

func (fsys MapFS) Sub(dir string) (fs.FS, error)

type MapFile

type MapFile struct {
	Data    []byte      // file content
	Mode    fs.FileMode // fs.FileInfo.Mode
	ModTime time.Time   // fs.FileInfo.ModTime
	Sys     any         // fs.FileInfo.Sys

A MapFile describes a single file in a MapFS.

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