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: ec_volume_test.go
    path of file: ./repos/seaweedfs/weed/storage/erasure_coding
    
    the code of the file until where you have to start completion: package erasure_coding

import (
	"fmt"
	"os"
	"testing"

	"github.com/stretchr/testify/assert"

	"github.com/seaweedfs/seaweedfs/weed/storage/needle"
	"github.com/seaweedfs/seaweedfs/weed/storage/types"
)

func TestPositioning(t *testing.T) {

	ecxFile, err := os.OpenFile("389.ecx", os.O_RDON
    
func TestPositioning(t *testing.T) {

	ecxFile, err := os.OpenFile("389.ecx", os.O_RDONLY, 0)
	if err != nil {
		t.Errorf("failed to open ecx file: %v", err)
	}
	defer ecxFile.Close()

	stat, _ := ecxFile.Stat()
	fileSize := stat.Size()

	tests := []struct {
		needleId string
		offset   int64
		size     int
	}{
		{needleId: "0f0edb92", offset: 31300679656, size: 1167},
		{needleId: "0ef7d7f8", offset: 11513014944, size: 66044},
	}

	for _, test := range tests {
		needleId, _ := types.ParseNeedleId(test.needleId)
		offset, size, err := SearchNeedleFromSortedIndex(ecxFile, fileSize, needleId, nil)
		assert.Equal(t, nil, err, "SearchNeedleFromSortedIndex")
		fmt.Printf("offset: %d size: %d\n", offset.ToActualOffset(), size)
	}

	needleId, _ := types.ParseNeedleId("0f087622")
	offset, size, err := SearchNeedleFromSortedIndex(ecxFile, fileSize, needleId, nil)
	assert.Equal(t, nil, err, "SearchNeedleFromSortedIndex")
	fmt.Printf("offset: %d size: %d\n", offset.ToActualOffset(), size)

	var shardEcdFileSize int64 = 1118830592 // 1024*1024*1024*3
	intervals := LocateData(ErasureCodingLargeBlockSize, ErasureCodingSmallBlockSize, DataShardsCount*shardEcdFileSize, offset.ToActualOffset(), types.Size(needle.GetActualSize(size, needle.CurrentVersion)))

	for _, interval := range intervals {
		shardId, shardOffset := interval.ToShardIdAndOffset(ErasureCodingLargeBlockSize, ErasureCodingSmallBlockSize)
		fmt.Printf("interval: %+v, shardId: %d, shardOffset: %d\n", interval, shardId, shardOffset)
	}

}