You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: layer_test.go
    path of file: ./repos/moby/layer
    
    the code of the file until where you have to start completion: package layer // import "github.com/docker/docker/layer"

import (
	"bytes"
	"errors"
	"io"
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"testing"

	"github.com/containerd/continuity/driver"
	"github.com/docker/docker/daemon/graphdriver"
	"github.com/docker/docker/daemon/graphdriver/vfs"
	"github.com/docker/docker/pkg/archive"
	"github.com/docker/docker/pkg/idtools"
	"github.com/docker/docker/pkg/stringid"
	"github.com/opencontainers/go-dig
    
func createLayer(ls Store, parent ChainID, layerFunc layerInit) (Layer, error) {
	containerID := stringid.GenerateRandomID()
	mount, err := ls.CreateRWLayer(containerID, parent, nil)
	if err != nil {
		return nil, err
	}

	pathFS, err := mount.Mount("")
	if err != nil {
		return nil, err
	}

	if err := layerFunc(pathFS); err != nil {
		return nil, err
	}

	ts, err := mount.TarStream()
	if err != nil {
		return nil, err
	}
	defer ts.Close()

	layer, err := ls.Register(ts, parent)
	if err != nil {
		return nil, err
	}

	if err := mount.Unmount(); err != nil {
		return nil, err
	}

	if _, err := ls.ReleaseRWLayer(mount); err != nil {
		return nil, err
	}

	return layer, nil
}