}
		buffer := make([]byte, test.blocksize, 2*test.blocksize)
		writers := make([]io.Writer, len(disks))
		for i, disk := range disks {
			writers[i] = newBitrotWriter(disk, "", "testbucket", "testobject", erasure.ShardFileSize(test.size), test.algorithm, erasure.ShardSize())
		}
		_, err = erasure.Encode(context.Background(), bytes.NewReader(data), writers, buffer, erasure.dataBlocks+1)

	volume := "testvol"
	filePath := "testfile"

	disk, err := newLocalXLStorage(tmpDir)
	if err != nil {
		t.Fatal(err)
	}

	disk.MakeVol(context.Background(), volume)

	writer := newBitrotWriter(disk, "", volume, filePath, 35, bitrotAlgo, 10)

	_, err = writer.Write([]byte("aaaaaaaaaa"))
	if err != nil {
		t.Fatal(err)
	}
	_, err = writer.Write([]byte("aaaaaaaaaa"))
	if err != nil {
		t.Fatal(err)

func BitrotAlgorithmFromString(s string) (a BitrotAlgorithm) {
	for alg, name := range bitrotAlgorithms {
		if name == s {
			return alg
		}
	}
	return
}

func newBitrotWriter(disk StorageAPI, origvolume, volume, filePath string, length int64, algo BitrotAlgorithm, shardSize int64) io.Writer {
	if algo == HighwayHash256S {