hybridgroup.gobot/sysfs/fs_mock.go

118 lines
2.6 KiB
Go

package sysfs
import (
"errors"
"os"
"time"
)
var _ File = (*MockFile)(nil)
var _ Filesystem = (*MockFilesystem)(nil)
// MockFilesystem represents a filesystem of mock files.
type MockFilesystem struct {
Seq int // Increases with each write or read.
Files map[string]*MockFile
}
// A MockFile represents a mock file that contains a single string. Any write
// overwrites, and any read returns from the start.
type MockFile struct {
Contents string
Seq int // When this file was last written or read.
Opened bool
Closed bool
fd uintptr
fs *MockFilesystem
}
// Write writes string(b) to f.Contents
func (f *MockFile) Write(b []byte) (n int, err error) {
return f.WriteString(string(b))
}
// Seek seeks to a specific offset in a file
func (f *MockFile) Seek(offset int64, whence int) (ret int64, err error) {
return offset, nil
}
// WriteString writes s to f.Contents
func (f *MockFile) WriteString(s string) (ret int, err error) {
f.Contents = s
f.Seq = f.fs.next()
return len(s), nil
}
// Sync implements the File interface Sync function
func (f *MockFile) Sync() (err error) {
return nil
}
// Read copies b bytes from f.Contents
func (f *MockFile) Read(b []byte) (n int, err error) {
count := len(b)
if len(f.Contents) < count {
count = len(f.Contents)
}
copy(b, []byte(f.Contents)[:count])
f.Seq = f.fs.next()
return count, nil
}
// ReadAt calls MockFile.Read
func (f *MockFile) ReadAt(b []byte, off int64) (n int, err error) {
return f.Read(b)
}
// Fd returns a random uintprt based on the time of the MockFile creation
func (f *MockFile) Fd() uintptr {
return f.fd
}
// Close implements the File interface Close function
func (f *MockFile) Close() error {
return nil
}
// NewMockFilesystem returns a new MockFilesystem given a list of file paths
func NewMockFilesystem(files []string) *MockFilesystem {
m := &MockFilesystem{
Files: make(map[string]*MockFile),
}
for i := range files {
m.Add(files[i])
}
return m
}
// OpenFile opens file name from fs.Files, if the file does not exist it returns an os.PathError
func (fs *MockFilesystem) OpenFile(name string, flag int, perm os.FileMode) (file File, err error) {
f, ok := fs.Files[name]
if ok {
f.Opened = true
f.Closed = false
return f, nil
}
return (*MockFile)(nil), &os.PathError{Err: errors.New(name + ": No such file.")}
}
// Add adds a new file to fs.Files given a name, and returns the newly created file
func (fs *MockFilesystem) Add(name string) *MockFile {
f := &MockFile{
Seq: -1,
fd: uintptr(time.Now().UnixNano() & 0xffff),
fs: fs,
}
fs.Files[name] = f
return f
}
func (fs *MockFilesystem) next() int {
fs.Seq++
return fs.Seq
}