diff --git a/src/internal/kopia/mockkopia/fs.go b/src/internal/kopia/mockkopia/fs.go
new file mode 100644
index 000000000..3346b70b1
--- /dev/null
+++ b/src/internal/kopia/mockkopia/fs.go
@@ -0,0 +1,93 @@
+package mockkopia
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"os"
+	"time"
+
+	"github.com/kopia/kopia/fs"
+)
+
+const (
+	DefaultPermissions os.FileMode = 0o777
+)
+
+type MockEntry struct {
+	EntryName    string
+	EntryMode    os.FileMode
+	EntrySize    int64
+	EntryModTime time.Time
+	EntryOwner   fs.OwnerInfo
+	EntryDevice  fs.DeviceInfo
+}
+
+func (me MockEntry) Name() string {
+	return me.EntryName
+}
+
+func (me MockEntry) IsDir() bool {
+	return me.EntryMode.IsDir()
+}
+
+func (me MockEntry) Mode() os.FileMode {
+	return me.EntryMode
+}
+
+func (me MockEntry) ModTime() time.Time {
+	return me.EntryModTime
+}
+
+func (me MockEntry) Size() int64 {
+	return me.EntrySize
+}
+
+func (me MockEntry) Sys() any {
+	return nil
+}
+
+func (me MockEntry) Owner() fs.OwnerInfo {
+	return me.EntryOwner
+}
+
+func (me MockEntry) Device() fs.DeviceInfo {
+	return me.EntryDevice
+}
+
+func (me MockEntry) LocalFilesystemPath() string {
+	return ""
+}
+
+func (me *MockEntry) Close() {
+}
+
+type mockReader struct {
+	e fs.Entry
+	io.ReadSeeker
+}
+
+func (mr mockReader) Entry() (fs.Entry, error) {
+	return mr.e, nil
+}
+
+func (mr *mockReader) Close() error {
+	return nil
+}
+
+type MockFile struct {
+	fs.Entry
+	OpenErr error
+	Data    []byte
+}
+
+func (mf *MockFile) Open(context.Context) (fs.Reader, error) {
+	if mf.OpenErr != nil {
+		return nil, mf.OpenErr
+	}
+
+	return &mockReader{
+		e:          mf.Entry,
+		ReadSeeker: bytes.NewReader(mf.Data),
+	}, nil
+}