Use fs.File as base for File interface

This is a stepping stone towards making go-billy more io/fs friendly.

Signed-off-by: Paulo Gomes <[email protected]>

Author: pjbgf

fs.go

@@ -3,6 +3,7 @@ package billy
 import (
 	"errors"
 	"io"
+	"io/fs"
 	"os"
 	"time"
 )
@@ -161,15 +162,15 @@ type Chroot interface {
 
 // File represent a file, being a subset of the os.File
 type File interface {
+	fs.File
+
 	// Name returns the name of the file as presented to Open.
 	Name() string
 	io.Writer
-	// TODO: Add io.WriterAt for v6  
+	// TODO: Add io.WriterAt for v6
 	// io.WriterAt
-	io.Reader
 	io.ReaderAt
 	io.Seeker
-	io.Closer
 	// Lock locks the file like e.g. flock. It protects against access from
 	// other processes.
 	Lock() error

internal/test/mock.go

@@ -2,6 +2,7 @@ package test
 
 import (
 	"bytes"
+	"io/fs"
 	"os"
 	"path"
 	"path/filepath"
@@ -135,6 +136,10 @@ func (*FileMock) Unlock() error {
 	return nil
 }
 
+func (*FileMock) Stat() (fs.FileInfo, error) {
+	return nil, nil
+}
+
 func (*FileMock) Truncate(size int64) error {
 	return nil
 }

memfs/memory_test.go

@@ -3,6 +3,7 @@ package memfs
 import (
 	"fmt"
 	"io"
+	"io/fs"
 	"os"
 	"runtime"
 	"testing"
@@ -14,6 +15,8 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+var _ fs.File = &file{}
+
 func TestRootExists(t *testing.T) {
 	fs := New()
 	f, err := fs.Stat("/")

osfs/os_test.go

@@ -4,10 +4,13 @@
 package osfs
 
 import (
+	"io/fs"
 	"reflect"
 	"testing"
 )
 
+var _ fs.File = &file{}
+
 func TestDefault(t *testing.T) {
 	want := &ChrootOS{}
 	got := Default