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 either the first error or a list of errors. Use errors.Is or errors.As to inspect.
Typical usage inside a test is:
if err := fstest.TestFS(myFS, "file/that/should/be/present"); err != nil {
t.Fatal(err)
}
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.
type MapFS map[string]*MapFile
func (fsys MapFS) Glob(pattern string) ([]string, error)
func (fsys MapFS) Open(name string) (fs.File, error)
Open opens the named file.
func (fsys MapFS) ReadDir(name string) ([]fs.DirEntry, error)
func (fsys MapFS) ReadFile(name string) ([]byte, error)
func (fsys MapFS) Stat(name string) (fs.FileInfo, error)
func (fsys MapFS) Sub(dir string) (fs.FS, error)
A MapFile describes a single file in a MapFS.
type MapFile struct {
Data []byte // file content
Mode fs.FileMode // fs.FileInfo.Mode
ModTime time.Time // fs.FileInfo.ModTime
Sys any // fs.FileInfo.Sys
}